Storm Australian Severe Weather Forum

Severe Weather Discussion => Tornado Alley Outbreaks and Severe Weather Worldwide => Topic started by: Jimmy Deguara on 01 May 2007, 06:54:02 PM

Title: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 01 May 2007, 06:54:02 PM
Hi,

It looks reasonably exciting to see some prospect chase days here in Tornado Alley. Moisture should not be a problem with ample moisture in the gulf as well as some fairly recent and regular rains in Texas this year and especially over the past couple of weeks.

Although there is action from 30th April through to 1st May 2007, the next trough looks to be a little more interesting for more clean action over SW Texas with good lower level turning. the guys will be here by then and we will be in a position to head out proper.

Macca and Chris are out in force after yesterday's action with a nice shelf cloud in southwest Texas. We'll see how they go today with some potentially good action if things can align well. The atmosphere is still messy after last night's and this morning's convection but we'll see how it evolves. the models do suggest that far SW Texas will be clear so I think that region can get something firing off from Mexico and crossing the border. Typical HP supercell variety. I am a little concerned with the upper level shear being too weak and especially in this region may become stagnated.

Regards,

Jimmy Deguara
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 02 May 2007, 12:51:26 AM
Hi,

A tornado watch has been issued for the target region given there is an outflow boundary. Also there is an existing storm most likely a supercell well to the NW in Mexico almost running parallel to the US/Mexico border. Any supercell the crosses the boundary can also become tornadic along this boundary or in Mexico for that matter.

We'll see how Macca and Chris go given they were targetting this region.

Regards,

Jimmy Deguara
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 02 May 2007, 04:40:27 AM
If Macca headed down where they said in our discussion this morning, they are on a tornado warned beast with hook echo! Very nice on NWS radar.

Hail too the size of tennis balls was reported from the storm 7pm CDT.

Regards,

Jimmy Deguara
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 02 May 2007, 06:08:22 AM
The western storm merger did wind up producing a tornado:

A TORNADO WAS REPORTED. THIS TORNADO WAS LOCATED NEAR BRUNI from the National Weather Service warning statement. Radar indicating large destructive hail.

Regards,

Jimmy Deguara
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Macca on 02 May 2007, 09:49:08 AM
Hey Jimmy,

Yep - we did head down here to far southern Texas and had a run in with a near-stationary HP supercell.  See below for the report.

We started the day in Big Spring (a bit late due to my late night last night and a small sleep in this morning).  A quick data check saw us heading S to try and get in front of the outflow boundary from the previous night’s convection.  It was aligned east west and was heading slowly southwards from about San Antonio to Del Rio.   

It was totally cloudy for the majority of the drive and we almost gave up but a our spirits were lifted when SPC issued a tornado watch box slightly further N than we’d previously though and then a freak wireless internet connection in Leakey allowed us to see the outflow boundary and the potential for some serious storms if they could utilize the boundary.  Low level flow was impressive to say the least with 850mb winds from the SE at 30-35knts.  Mid level flow was relatively weak with 30knts at 500mb from the W.  Overall, shear was easily enough for supercells but a little more speed shear would’ve been nice…hehe. 

A cluster of strong storms was riding the boundary in the eastern parts of the T-watch box quite a way off to our S but we knew this was really our only hope.  We wanted to get to Freer as this gave us some better road options so we hoofed it down I-35 and then east on SR-44 towards Freer.  Unfortunately (yet somehow this wasn’t something you could complain about), the storm turned hard right and went from moving in an ENE’ly direction to going SE and then almost due S!  It was training along the boundary and moving very very slowly (10-15mi/h).  It sat over Freer for over an hour with large hail reports (up to tennis balls) was reported from parts of Freer for 1 hour and 5 minutes. 

We stopped to watch the base from the WNW side but it soon was hidden by the RFD.  We tried to punch through the cell (not the RFD so much but moreso the edge of the core) in an effort to get to a SW’ward road option but encountered strong winds, driving rain and some large hail.  The hail started off relatively small (1-2cm) and it wasn’t until we got within 5mi of Freer that it got large.  A few LOUD donks on the car indicated the hail was getting bigger and then we saw some larger stones bouncing on the road.  We estimate these to be about 4-5cm but we saw nothing larger than that and these were quite sporadic.  We did get a blasting of hail in the 2-3cm range which was deafening on the car and we realized that we couldn’t keep going this way so we had to turn back.  It was 40mi back to I-35 (our only south road option other than going further into the hail).  We cut our losses and started heading back to I-35 and the storm kept building westwards along the boundary and moving basically due S.  We headed to Laredo with a few stops for photos of the structure on the way and then as the sun went down, we headed about 5mi east of Laredo to get some lightning pics as the storm moved off to the SE.  While we were there, another storm developed rapidly on the outflow boundary right over Laredo and we were alerted to it only when it put out a flash of lightning.  No more than 5 minutes later, it was dropping CG’s only 2mi away – this made for an AWESOME sight with the precip being lit up by the setting sun and the blue CG’s streaking through it.  They weren’t frequent but they were very nice.  Eventually we retreated to the car and the cell weakened somewhat (but not before radar indicated it had up to 5cm hail – not bad for a storm that was about 30mins old).  We headed back into Laredo and noted some minor road flooding from the storm.  We have stopped here for the night to gather ourselves after a somewhat up and down day.  We discovered this evening that one of our headlights got smashed (most likely by hail) however the car suffered no other damage. 

Tomorrow looks relatively similar to today.  Strong instability (LI’s of -8 to -9 and CAPE of 3000 j/kg) with moderate low level winds of 20-25knts at 850mb and only moderate mid level flow of  30-40knts at 500mb.  Again storms will probably be most severe in the vicinity of outflow boundaries and it will be a matter of trying to find one of those tomorrow.  Our plan is to head N along I-35 – moreso to get back into a reasonably central position but also into the area where the most favourable mix of instability and shear occur.  It also looks like this southern area may be a little “tapped” from today so might not have as much potential tomorrow. 

Will try and post an update in the morning.  This has certainly been quite a hectic start to this trip with 2000mi covered in just 4 days.  2 very impressive storm days to start with.  Chris mentioned yesterday that in comparison to our last trip here in 2005, we got our first storm 6 days earlier than last time so hopefully if this trend continues, we should do ok this year.

Link to some pics from today are here… 

http://macca.bsch.au.com/gallery/20070430

Thanks for the thoughts on the reports peeps…keep them coming…

Macca & Chris
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Macca on 02 May 2007, 07:11:33 PM
Hi all,

In Laredo this morning just doing some washing and taking care of business ;). 

Today is looking relatively similar to yesterday although with slightly less upper level support (which is offset by slightly more juice in the lower levels).  LI's are progged to be around -7 to -8 and CAPE is forecast to get into the 3000's across south central Texas.  Overnight (and morning) storms have left a couple of outflow boundaries - both aligned relatively east-west.  One is sitting from about Austin to Junction and another sitting a little further NW from Abeline to around Midland.  Instability is relatively indifferent across these two boundaries (which should be the focus of convection this afternoon) but there are some differences in shear.  Surface winds look to be from the SE at about 15-20knts across both regions, however, the Austin - Junction OFB should see 850mb winds of 25-30knts from the SSW with a moderate low level jet (LLJ) currently running along the I-35 corridor from San Antonio to Dallas.  The Abeline OFB has more slack 850mb winds (and 500mb winds too) so we'll probably focus on the Austin boundary.  500mb winds across the boundary look to be in the 30-40knt vicinity so not overly strong but its about the same as yesterday and with the strong instability, a few supercells shouldn't be too hard to find.  We have some things to take care of in San Antonio this morning but after that, we'll head up I-35 to Austin (or near to there) and see how this afternoon shapes up.

Tomorrow is looking potentially potent as a vigorous shortwave upper trough moves into western Texas.  Not only does the mid level flow increase to 40-50knts from the west and the low levels maintain their 20-30knt SE'ly trend, the instability increases even moreso than today as the upper trough starts to have an influence.  The   latest GFS run shows LI's of -11 to -12 and CAPE in excess of 4000j/kg.  It could be quite a day tomorrow if this comes off.  There are a few differences in the models as to the timing of the upper trough but I wouldn't be suprised to see a moderate risk upgrade for tomorrow.

Will keep you all posted as to our happenings today. 

(Long term model runs do not look like giving us a break for at least 6 more days...hehe).

Macca & Chris
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 02 May 2007, 07:28:54 PM
1st May 2007

Target region seems to be near Austin to Waco though I would not be surprised if initiation occurs in the baked up region near San Angelo. In discussion with Macca, I do believe that storms will require to drift S in order to maintain some clean inflow. Shear is moderate and instability is high - near 3500 - pretty nice for early May.

2nd May shows slightly in different shear though high CAPEs. I would not be surprised seeing over the 5000 CAPE mark on this day so it can help provide a focus for some explosive development if the strong cap holds things down. Watch out west Texas.

Regards,

Jimmy Deguara
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Michael Bath on 03 May 2007, 03:03:28 AM
Interesting right mover south of Brownwood Texas after 5pm. Wonder if any of the tourists are on to it !

(http://australiasevereweather.com/storm_news/2007/radar/200705012227.png)

(http://australiasevereweather.com/storm_news/2007/satpics/200705012225.jpg)

EDIT: is it a right mover ?  Almost stationary with backbuilding
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Macca on 03 May 2007, 08:07:42 AM
Yep - we were on it.  No tornadoes (only 1 reported early in its life), no hail (reports of 4.25 inch hail about 3 miles from where we were) but some fairly nice structure.  Report and pics to come soon (slightly distracted by the lightning outside atm).

Macca & Chris
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Macca on 03 May 2007, 09:12:25 AM
Hi all,

Ok so we took care of some business in San Antonio early this afternoon after doing some washing at our hotel in Laredo.  After having to change cars (due to previous day’s damage), we set up the laptop again to see the first cell of the day go up along the Austin boundary (which had drifted N from where it was in the morning).  The cell exploded rapidly and was tornado warned with a confirmed tornado after just 90 minutes.  Unfortunately it was still quite a ways off to our NW.  So we blasted N along US 281 to Round Mountain before heading NW to Llano along SR71 and then W along SR29 to the intersection of CR405.  We made our first stop just past CR405 where we watched as the storm put down a nice wet RFD to our N and the wall cloud wrapped up very nicely.  Mid and low level inflow bands were present and the structure was quite nice.  (We later found out that this RFD to our N produced 4.25 inch hail not too far from where we were!!). 

After watching this for a short while, it got a little close so we headed back to CR405 where we headed south about 1mi to Castell where we stopped again for more photos.  The inflow band had become quite large and the wall cloud had wrapped up very nicely.  We were sitting quite close to the vault region downwind of the main updraft and we were cautious of hail after yesterday.  The rotation at this point was very impressive, however, the lack of low level winds probably prevented this cell from dropping more than just one tornado.  The storm was quite a way further west than we’d hoped things would develop and as such, the better low level shear was off to the east, however, the only action out to the east was linear.  After a while, and then tried to go further S along CR105 (an extension S’wards of CR405) but it turned to dirt about 200m along the road.  A quick U-turn saw us make it back to Castell just as the rain started.  Again we were worried about hail but we managed to escape along FM152 to the east back up to Llano through the less intense part of the storm.  We lost a bit of ground on the storm here due to the storm cutting off a few more ideal road options but we scooted southwards to Fredricksburg and then NW along US87 for about 8 miles where we again intercepted the storm as it wrapped up in spectacular fashion.  Inflow striations wrapped around the updraft, a low level inflow band extended off to the east and the guster marking the front of the RFD was wrapping around towards us from the W.  We were basically looking into the notch which is the only place you can be on a HP to see anything.  We didn’t see anything…hehe.  This was the last gasp for this cell as it become more outflow dominated.  We dropped back into Fredricksburg so as to avoid another hail pummeling and then dropped SW where we stopped and watched as the storm pushed out towards us (in a very much outflow dominated manner).  We then dropped down to Kerrville where we have shacked up for the night.  The storm moved over here a while ago and gave some really heavy rain and some awesome lightning.  I managed to get a few CG’s on the digicam – one was quite impressive but I was disappointed I didn’t get the other half of this CG which hit a radio tower about 100m from here (behind me)…the instantaneous crack of thunder that followed nearly required a change of underwear for me. 

The storm is still flashing away off to the S and SW (and W) but its into the anvil crawler phase now and they are too distant for photography. 

I’ll post more on tomorrow’s set up either later tonight (its nearly midnight) or tomorrow morning.

Link to today’s pics are here…

http://macca.bsch.au.com/gallery/20070501

Macca & Chris
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 03 May 2007, 08:15:30 PM
Hi Macca,

Awesome structure - pity it could not hold down longer so we could arrive there from DFW airport. We left 3:30pm so we arrived 8pm ish  given it slowed down and then back built. I guess my target initiation was in that region well San Angelo region.

So I see base ball hail warnings yesterday on that storm and then this morning more base ball hail warnings. Wow!

We are in Junction, Texas - Macca and Chris were at Kerrville not far away at all. Awaiting for things to begn firing across the border or in Texas NW of here. An existing complex that produced the very large hail is moving SE hopefully it does not ruin the day.

Regards,

Jimmy Deguara
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Macca on 03 May 2007, 09:46:06 PM
Hey Jimmy,

Yeah - there was one report of softball hail from yesterday from fairly close to where we were. 

Today is an interesting one.  A vigorous short wave upper trough is moving across southern New Mexico and into western Texas.  Ahead of this, a very moist airmass is in place.  We are in Kerrville at the moment.  Its 12:30pm and its drizzling and has been all morning.  A dryline has set up across far NE'rn Mexico with DP's in the low 70's ahead of it and in the high 40's behind it.  Very well defined.  There is a bulge in this dryline which is fairly close to Del Rio.  There is also an outflow boundary which is pushing quite quickly SE which could interact with the dry line in about 2 hours right near Del Rio!  This will probably become our target to start the day as storms should develop where these two boundaries intersect in the next 2-3 hours and move eastwards towards Texas.  500mb temps are quite cold (-15C) and with surface temps possibly getting into the mid 80s' combining with low 70's DPs, CAPE values should exceed 3500j/kg.  This bodes well for some very very large hail.  Shear is adequate for strong supercells as well and if storms can make it across into Texas, a moderate southerly LLJ of 20-30knts is waiting to feed these storms.  Mid and upper level jets are entering the south central Texas region this afternoon with 500mb winds forecast to increase to 40-50knts from the west and the upper level jet is forecast to increase to 80-90knts.  There is some nice divergence aloft too just incase there wasn't enough lift already. 

SPC just issued an updated convective outlook for today and have a 5% chance of tornadoes and 30% hatched area for hail (meaning 30% chance of hail greater than 2 inches within 25 miles of any given point in the area).  They mention that they considered upgrading to moderate risk but a few uncertainties have kept it to a slight risk only.  CAPE values are currently around 5000jkg over Mexico where the cloud has cleared.

Things may go a little linear later today but hopefully some nice supercells will develop before that happens  :) .

Macca & Chris
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Michael Bath on 04 May 2007, 05:38:45 AM
Quite a strong meso showing on the base reflectivity and base velocity scans from Laughlin Air Force Base Texas Radar @ 1.23z (8.23pm CDT)

(http://australiasevereweather.com/storm_news/2007/radar/200705030123ref.gif)

(http://australiasevereweather.com/storm_news/2007/radar/200705030123vel.gif)
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Macca on 04 May 2007, 09:42:53 AM
Hi all,

Today had the potential to go crazy and it did.  But not for us.  We made a decision during the early afternoon to head S from Kerrville to Uvalde.  At the time, we figured the OFB and the dryline would intersect pretty close to Del Rio.  CAPE was also much higher further S and the cap was somewhat stronger so we figured storms would remain discrete for longer.  All of this happened…a massive storm blew up about 40mi over the border into Mexico.  We saw this on radar from Uvalde and we figured that with the 40knt mid level jet from the west and relatively weak low level flow over in Mexico, that this storm would move in a generally eastward direction and cross over into Texas somewhere around Eagle Pass (which was hit by a tornado only just over a week ago).  But…the storm took a HARD right turn and moved SSE with a massive hook echo showing up on radar.  The storm basically paralleled the Texas/Mexico border for hours with the storm sitting about 25-30mi over into Mexico.   We tried to go S to intercept it if it was eventually to cross the border but we rain into dirt roads so we basically had to give up on this storm.  What made things worse was that many of the places we had driven through earlier today were subsequently hit by some very nice supercells (Kerrville, Uvalde).  I’m guessing that the OFB stalled across the southern Hill Country and supercells just developed along this as the airmass destabilized late in the afternoon (it was still 8/8 and drizzling at 4pm in Uvalde).   We eventually got some minor redemption finally getting onto the tornado-warned storm near Frio about half an hour after sunset.  We managed to get into a decent position which allowed us to look into the notch of this HP supercell which was relatively frequently lit up by lightning – we didn’t see anything.  We also met another chaser who had also gone for the Mexican stuff (making us feel not quite so bad).  We were treated to a pretty nice lightning display (which is still going as I type this as we are driving N along I-35 – its 11:35pm). 

In hindsight, our forecast was pretty spot on.  The most isolated storm/s developed further S (ie away from the MCS) and were probably the most impressive in terms of radar echoes.  The “target” cell developed just ahead of the dryline/OFB intersection and remained discrete for its entire life pretty much (its still going!).  The HUGE problem was that it was in Mexico and we weren’t (not a visa/passport issue – but again the rental car issue).  I’m still quite surprised at how hard this storm turned to the right – I would’ve thought this would be more likely on a day like yesterday with weaker mid-level flow.  Overall a fairly frustrating day but if the only reason for a semi-bust is an international border, then things can’t be too bad ;).

We are making tomorrow a driving day.  We are going to boot N along I-35 as far as we can as Friday onwards looks very nice.  A strong cap looks to be in place S of about I-70 so we’ll try and head for say Wichita, KS tomorrow (about 550mi) with the thought of wanting to be in the vicinity of Hayes, KS by cap breaking time on Friday. 

Macca & Chris
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Macca on 05 May 2007, 07:54:48 AM
Day 7

Although all reports may not yet be in, SPC is showing that no tornadoes were reported from the storms over south western Texas yesterday (not sure about the Mexican storm yet although it is highly likely that it was tornadic).  So even though we missed a lot of the action and probably some great structure in Texas, we didn’t miss out on tornadoes. 

Today was a designated driving day to get into a good position for tomorrow (more on that below).  We left San Marcos (between San Antonio and Austin, Texas) at about 10am and basically drove all day and we have stopped for the night in Wichita, Kansas (yep – we drove through a lot of Texas and ALL of Oklahoma today – about 580mi (925km). 

Just a little bit of info on today…the “action area” of the upper trough from yesterday was still hanging around eastern Texas into Louisiana and Arkansas and the centre of the weakening upper level circulation was sitting over central Oklahoma and moving eastwards.  A considerably moist boundary layer was present over the eastern half of Texas and there was still some reasonable (but weakening) shear.  LI’s were around -7 to -8 over south eastern Texas and getting up to about -4 to -5 over north eastern Texas so there was still quite a bit of instability around.  A few isolated storms (possibly short-lived supercells) developed near DFW late this afternoon but we had already left by that stage.  Two or three more lines of storms developed over far eastern Texas, Louisiana and Arkansas and these had plenty of storm warnings on them but that area isn’t the greatest to chase and it was very linear.   We basically decided to make today a “relaxing driving day” as opposed to a full on chase day followed by a 6 hour drive after chasing and then another 6-8 hour drive tomorrow to the target area.  From what we saw on radar today, this probably was a decent move as I don’t think we missed out on too much over Texas. 

We did run into a line of storms which formed along some sort of boundary near Oklahoma City.  Hail of up to 4cm was reported from these storms quite close to where we were but these storms were relatively high based.  Given that they were located near the centre of the cold pool, the updrafts were quite crisp.  We also got a fairly AWESOME sunset here in Wichita tonight.  It was nice to have a “day off” today (even though we saw plenty of storms on the drive N).  We have plenty of time to watch things begin to evolve for tomorrow. 

Ok – now for tomorrow.  The first thing to note is a significant upper level trough digging into the central high plains tonight and tomorrow.  This upper level feature is forecast to stall over the high plains for the next 4 days (Fri – Mon) with GFS finally pushing it eastwards by day 5 (to the eastern parts of the plains states) and then into the Mississippi River valley area on Day 6 in a weaker state.  This finally sees a ridge push into the plains, giving us some time to recover from this somewhat hectic but at the same time very welcome start to our trip.  If this upper level scenario comes off, we will have had significant chase days on 9 of the first 10 possible chase days. 

So…this upper level trough – the timing of its arrival tomorrow and its impact on surface features is still in question with GFS and NAM varying somewhat as to the outcome for tomorrow’s convection.  It is currently having an effect on NE’rn Colorado and eastern Wyoming where storms developed along the front range today.  This evening, a well mixed boundary layer sees dew points in the low 60’s (16-17C) across all of eastern Oklahoma and Kansas with a warm front currently moving slowly northwards through central Kansas.  Higher DP’s (65-70f’s) are present over central Texas at the moment.  Both GFS and NAM are showing slight increases in moisture levels tomorrow so that DP’s should be around the mid 60’s (18-19C) by prime time. 

With the approaching upper trough, a dryline is progged to set up across south western Nebraska extending down through western Kansas, western Oklahoma and into west north central Texas.  Significant pressure and temperature gradients between the upper level trough and the developing upper level ridge over the great lakes/missisippi river vally region is set to cause some very nice shear late tomorrow (and even more insane on Saturday).  Sharpening of the dryline in response to the approaching upper trough is going to result in a low level jet (LLJ) of 30-35knts (at 850mb) from the SE.  This is being overlayed by strongly diverging winds at 700 and 500mb’s and also in the jet stream (lets say 250mb).  700mb winds are SSW’ly at 40knts, 500mb winds are SW’ly at 45knts at 250mb winds are SW”ly at 70ktns.  Instability is not an issue with CAPE’s extending from 2000j/kg over south western Nebraska up to 4500j/kg over Texas and LI’s of -4 to -7. 

So, we have shear, we have instability…what is left in our equation?  Trigger.  We have one of those too…the convergence on the dry line.  So we should have some freaking awesome storms right?  Well…yes…BUT…there are two other things we need to consider.  These two things are where GFS and NAM have some interesting differences (interesting given we are only 24hrs out).   The two things we need to look at (which are linked) are the cap and focus points for convective initiation given the varying strength of the cap along various parts of the dryline.  GFS has some very warm 850mb temps sitting over the dryline from Texas up into central Kansas.  850mb temps of 24C extend all the way up to northern Kansas (lets say Hays) but north of there, the cap weakens to 21C and then 18C in quite a short distance.  A quick look at surface RH (basically the DP), GFS has a dryline bulge right near Hays.  A bulge in the dryline is often the focus of convection and frequently results in any supercells becoming tornadic.  The reason for the focus of convection is that it acts as a convergence zone for moisture and as a result is often the place where a strong cap can be broken.  The reason for supercells becoming tornadic is that the bulge in the dryline causes the surface winds to curve around into the corner created by the bulge, giving the low level flow a more easterly component and increasing the SRH in the vicinity of any storms that develop in this area.  (Feel free to correct me if this is not totally right or if there is a better way to describe this).  So GFS has the bulge sitting up on or just north of I-70 (which runs E-W across Kansas about 2/3rds of the way up).  The place to be in this situation would be to sit just NE of the dryline bulge and wait for convection to develop.  It is not uncommon for supercells to fire south of the dryline bulge too if the cap can be broken and when this does happen, these supercells tend to be very isolated and photogenic.  If the GFS scenario comes off, I have significant doubts as to whether any convection will initiate south of the bulge with the very warm 850mb temperatures (ie 24C+).  Some chasers are convinced that the significant lift associated with the approaching upper trough will be enough to break the cap but I made a rule when I was here last time (after 3 clear sky busts) that I wouldn’t chase an area which had 850mb temps of >20C.  Tomorrow will be no different.  The NAM scenario is similar to the extent that it also has a dryline bulge however, it situates it about 60-70mi further S near Great Bend, Kansas (almost right in the middle of Kansas).  This results in the main area of convergence being in a higher moisture area and thus instability is quite a bit higher (2000-2500j/kg with GFS compared to 3500-4000j/kg with NAM).  The main difference arises with the 850mb temperatures extending S of the dryline being in the 20-22C range.  This is more likely to be breakable than the GFS scenario.  If this was to come off, a few isolated very strong supercells would probably develop S of the bulge in southern Kansas into central western Oklahoma. 

Given the combination of shear and instability tomorrow, I think we can expect to see some very strong supercells develop with tornadoes quite likely with any supercells which form (whether in the bulge or S of there).  Very large hail is also likely (3-4 inches/6-10cm) as are damaging winds.  SPC has currently only gone for a slight risk due to the uncertainty regarding the cap strength (and thus how widespread storms will be tomorrow), however, I think we will see an upgrade to a moderate risk at least for central/north central Kansas and probably southern Nebraska for tomorrow, possibly extending quite a way to the east (moreso N of I-70).  Convection should evolve into an MSC in the late evening as the LLJ (850mb winds) strengthens futher to 50-60ktns.  This should move eastwards across northern Kansas and southern Nebraska overnight tomorrow and through Saturday morning.  The likely development of this MSC and the potential for this to have severe weather all night across the border regions of Kansas and Nebraska should only strengthen the case for a moderate risk to be issued for tomorrow. 

At the moment, there is really no way of telling which of the two scenarios is going to be in place by prime time tomorrow afternoon, however, either way, we will most likely be playing the dryline bulge (about 95% sure).    This is going to be the best chance of getting convection to initiate before dark and also the best chance of tornadoes (there is a decent chance the dryline could fire further S after dark as the lower levels cool and the cap weakens…this could be nasty if this happens given the strengthening LLJ…).

We will check data tomorrow morning (we have to check out of here by about 10-11am) and it should be clearer by then where exactly this bulge is going to be.  Every chaser and his/her dog will be out an about tomorrow and Saturday as this is looking to be one of the best set ups for the year so far.  We are expecting significant chaser convergence in the vicinity of the dryline bulge tomorrow although the chance of more isolated convection further S along the dryline will draw some chasers away from the crowds.  We should have time to post an update tomorrow morning. 

For now…we just sit and wait. 

Macca & Chris 
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: David C on 05 May 2007, 11:03:19 AM
Good luck guys, should be some REAL plains action over the next few days. While I would prefer the upper trough the eject out more vigorously (more rapid destabilisation), it should not matter as there will be Kansas specials on offer in anycase (4000+CAPE and 60+knots 0-6km). It will be the first time quite a few of you guys there will have experienced this magnitude of SVR so take it all in :)



 
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: nzstorm on 05 May 2007, 01:50:19 PM
Yes, best of luck for what looks like a very interesting few days of chasing. 

I'm looking forward to reports and pics.   

I start chasing on the 12th.
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 05 May 2007, 05:33:46 PM
Hi all,

We had a surprisingly interesting day yesterday with a Lp to classic supercell going crazy near Hillsborough! Lightning bolts from the anvil made it dangerous to be out of the vehicle and the organisation to supercell status was incredible. It was very close to producing a tornado with rapid rotation. There was absolutely no chaser that we saw around this storm because it developed and organised too quickly!

Pics later - we are enroute to Kansas after pulling off a miracle with car hire!

Regards,

Jimmy Deguara
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: David C on 06 May 2007, 07:50:17 AM
For posterity>>

Unfortunately, it seems that the town of Greensburg KS has taken a direct hit and there is a tornado emergency current.

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE DODGE CITY KS
1034 PM CDT FRI MAY 4 2007

KSC047-097-151-185-050400-
/O.CON.KDDC.TO.W.0027.000000T0000Z-070505T0400Z/
STAFFORD KS-EDWARDS KS-PRATT KS-KIOWA KS-
1034 PM CDT FRI MAY 4 2007

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 1100 PM CDT FOR
NORTHEASTERN KIOWA...NORTHWESTERN PRATT...SOUTHEASTERN EDWARDS AND
EXTREME SOUTHWESTERN STAFFORD COUNTIES...

AT 1031 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS AND STORM
SPOTTERS WERE TRACKING A LARGE AND EXTREMELY DANGEROUS TORNADO.  THIS
TORNADO WAS LOCATED 4 MILES SOUTHWEST OF TROUSDALE...MOVING NORTHEAST
AT 25 MPH.

* LOCATIONS IMPACTED INCLUDE...
  FELLSBURG...
  TROUSDALE...
  HOPEWELL...
  RURAL RESIDENCES OF NORTHEASTERN KIOWA...NORTHWESTERN PRATT...
  SOUTHEASTERN EDWARDS AND SOUTHWESTERN STAFFORD COUNTIES.

TROUSDALE IS IN THE DIRECT PATH OF THIS VIOLENT TORNADO...TAKE
COVER IMMEDIATELY!!

THIS STORM HAS A HISTORY OF PRODUCING TORNADOES CAUSING SIGNIFICANT
DAMAGE!
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: David Brodrick on 07 May 2007, 06:29:50 PM
OMG, check out these aerial photos of Greensburg:

http://www.kansas.com/static/slides/050507tornadoaerials/pages/_MG_0319.html

Dave

words words words
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jeff Brislane on 08 May 2007, 03:53:38 AM
It's a fine time for Stormtrack to remove the Target area access for visitors. It seems that visitors are contributing to the forum overloading and being shut down they have removed visitor access as a result. Great but it takes forever to join this stupid forum and thenif you don't post your membership gets canned! What are you supposed to do if you want to keep up with the latest developmenst and chase reports???

Lets see, the BoM website gets about 100,000+ hits a month and they don't seem to have a problem. I think Stormtrack needs to pay for more bandwidth, it's not like it's all that expensive over there!

Kiss goodbye to my stormwatching season :-(

Jeff.
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Michael Bath on 08 May 2007, 04:30:13 AM
This is a particularly impressive VIS satpic at 23.45UTC (6.45 CDT) for central Texas.  SPC has a rope tornado spotted at the time.

(http://australiasevereweather.com/storm_news/2007/satpics/200705062345.jpg)


Have to agree with you Jeff at Stormtrack - really peeved at no access to the reports, and they have shut down registering too.

MB
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Macca on 08 May 2007, 06:33:58 AM
Hi all,

The first part of the following post was written on Friday night as we were driving to a safe location away from the cyclical tornadic supercell...

Well – today turned out to be another very frustrating and also very sobering day.

I won’t spend long talking about the day apart from the fact that the cap held over all of Kansas all day. The cap broke down in the far north eastern Texas panhandle and a tornadic storm moved into far north western Oklahoma. Only minor damage was reported from this storm. A left split from this storm moved NE through the OK panhandle and into southern Kansas where it developed into a monster cyclical supercell. This supercell became tornadic just before dark (8:30pm) and it is now 12:30am and this cell is still raging through south central Kansas and has produced numerous large, violent tornadoes.

We tried to get in a position to view the storm near Greensburg at around 9:30pm, however, a very large tornado which was on-going during our northward run and this crossed the road we were on about 20mi ahead of us. Unfortunately, this large, violent tornado hit Greensburg and rural properties to the south of there. Other small towns and rural areas to the NE of this location have also been hit by this long-lived, violent tornado producing storm (it has produced several large tornadoes).

Our chase was cut short as we drove N along US 183 about 5mi S of Greensburg when we reached the place where this very large tornado had crossed the road (in a near parallel fashion – the tornado was moving NNNE) just 15 minutes earlier. Power lines were strewn all over the road for about 1-2mi like spaghetti, power poles were leaning at a 45 degree angle if they weren’t snapped off, trees were stripped bare, LARGE farm machinery was overturned (possibly dumped upside down). We could hear cows mooing in agony, a poor dog had endured the tornado and somehow survived but was terrified. We came across 3 properties which all had EXTENSIVE damage. The last one which we stopped at had a family sitting in a car who had driven here to search for their relative in what remained of the house (it was completely destroyed). An elderly woman in the vehicle had also had her house destroyed and it was her son’s place where they were searching for her son. Her daughter was with her, however, they had not heard from the missing person since the hail started at his house. These people were in shock. After about 5 minutes they received a call from a friend who informed them that the missing man was ok. The elderly woman wanted to go home to bed but her house was no longer there. We left them at this point to leave them to come to terms with what had just happened to them – they had just lost two homes in the one family. We headed back to the S back through the damage. Gas pipes had ruptured along the road and gas could be heard hissing out of these pipes. This place was like a war zone.

Emergency vehicles from all over the place were/are heading for Greensburg which took a direct hit from this same tornado. From the limited information we have heard, this violent tornado hasn’t left much in Greensburg. As I type this, more emergency vehicles can be heard outside either arriving at the hospital here in Pratt or heading out to help. This tornadic storm is still going near Great Bend with very strong hook echoes (note plural).

Certainly a very sobering experience and one you would never hope to happen. It will be a miracle if there are no fatalities from this event tonight. A long lived, violent tornado producing supercell at night is the last thing anyone wants.

Macca & Chris

……………………………….

So that is what I wrote the other night. Just to add to that, there have now been several fatalities reported with more likely to be found when rescue/clean up workers clear more of the debris. As you have seen from the links posted on this thread, this was a massive tornado (officially 1.4mi wide and upper end EF4 or lower end EF5 – yet to be confirmed) and the people of Greensburg had no chance. Dodge City NWS issued the tornado warning for Greensburg 20 minutes before it hit so the people of town at least had some time to take shelter….but not many shelters withstood this violent tornado. People who took shelter in their basements ended up being trapped when their houses just collapsed on them. I could go on and on with all the stories we have heard over the last 24hrs. It has been estimated that 95% of the structures in Greensburg have been severely damaged/destroyed – I don’t know how a town can recover from this.

It was certainly a very surreal experience for us and for many chasers that night. Coming across such extensive damage to property/people makes it really hit home how vulnerable we are. One thing we noticed yesterday was the really strong sense of community in this area. People from all over central/SW’rn Kansas were pulling together to donate food/shelter/money for the people of Greensburg. Unfortunately yesterday (Saturday) saw another round of severe weather in the exact same area and many towns in south western and central Kansas were under multiple tornado warnings again less than 24hrs after the previous bout. Greensburg was tornado warned 3 more times yesterday. And today isn’t looking great for them either with a 3rd day in a row of severe storms (and possibly strong tornadoes) to develop over the same area this afternoon.

Ok – so yesterday was a HIGH risk day (per SPC convective outlook) and this morning (Sunday), there has been 91 preliminary tornado reports across 7 states. This is likely to decrease by nearly half as many of these tornadoes have been reported more than once.

We started our day in Pratt, Kansas. A line of strong storms developed early in the day (11am-12pm) and quickly became supercellular. This line of storms didn’t produce many (if any tornadoes) and by mid afternoon these were moving off into north central kansas. We drove around checking out a few of these storms but they didn’t seem to be able to get really organized (I think the instability this early in the day was not enough to stand up against the insane shear…70-80knts at 500mb). Later in the afternoon, more storms developed on the southern end of this line over NW Oklahoma and SW Kansas. We were in Great Bend at the time and decided to head towards Dodge City area to pick up one of the more isolated storms in this line. (There were 3 storms to our SW to choose from, we picked the middle one to start with). We had to drive west of the most northern of the three storms to avoid its core and it wasn’t long before our storm was clearly in view. We got in a nice position to the ENE of the base and shortly after we stopped to watch, a tornado warning was issued for this storm (based on Doppler indicated rotation). Surface winds increased as we watched and they swung more to the SE (as opposed to S’ly as they had been for most of the days). The cell started to look quite nice for a while. It put out a big outflow push as an RFD came down to the west of the base and a nice wall cloud developed and had some rapid scud motion and rotation briefly. We were pretty close at this stage and had to boot eastwards to get out of the way.

Eventually, the outflow appeared to get the better of this storm so we left it to race off to the NE. Another nice cell was coming up from the SW so we dropped back into Pratt, gassed up and then headed west to intercept this tornado warned storm (based on spotter reports of confirmed tornadoes). We waited about 5mi Wof Pratt for the precip to pass over the road and then we headed into the action area. This is where things got interesting. We watched the base for about 10 minutes and saw some more rapid scud motion but no torandoes. We moved back east to get to a north road option and we did this several times over the next 2 hours - jogging east and then N to intercept the storm as it cycled through tornadic phases much like the previous evening. We saw what looks to be a tornado which emerged from behind the storm (see pics) at about 8:15pm looking NW towards Trousedale and then as we pushed N along SW 70th Ave from Bayers, we approached US 50 from the S and saw a very nice solid stove pipe tornado on the ground near Macksville to our NNW. Fortunately, Macksville was spared by this tornado. It was right on dusk at this point and the tornado was difficult to see (no digi pics) but the lightning illuminated the tornado nicely on video. The road north was blocked by EMA (emergency management) so we just had to watch from a distance of about 3mi along with quite a few other chasers. This tornado dissipated shortly after this and another tornado developed from the same circulation about a minute later (see pic/s). This was a smaller elephant trunk tornado and this lasted only 30 seconds or so. A much larger tornado was off to the N of us (about 5mi) however, given our location and the now near darkness, we weren’t able to see this.

We dropped back S a little and then raced eastwards again before another northward jog to position ourselves NE of Stafford. We were now ESE of the main circulation, looking almost due W. Several large lowerings were looking ominous to our WNW and after talking to a few chasers last night, they were about 3mi to our W and were very close to a large wedge tornado. We’ll have to check our videos at some stage but this may’ve been what was off to our WNW. After watching this for about 10 minutes, it appeared to weaken and the whole line of storms became less discrete and looked much less likely to produce more tornadoes. We decided at this point to call it a day. We headed east to Hutchinson, KS were we finally too some time to rest and catch up on what has been a crazy few days. In review, we definitely got 2 tornadoes yesterday, possibly as many as 4. Its nice to get the first one under the belt and hopefully we can get a few more in our time here. I’d really like to get some in full daylight so we can get proper photos but I won’t complain about what we got.

Today is looking interesting again with the possibility of more strong tornadoes. There is a lot of on-going convection already over much of KS, OK and TX but the boundary (cold front) is forecast to retreat westwards today and another upper level impulse is set to over run this boundary later today. It’s a little difficult to work out how things are going to pan our given all the convection at the moment but if this can clear out by early-mid afternoon, there should be time for sufficient instability for supercells. Shear is also still quite nice with 30knts at 850mb from the SE overlayed by 50knt at 500mb from the SW. If this comes off, there is more turning in the lower level winds than the past two days and with the mid-level steering winds being slightly weaker, storms may be slightly slower moving. At the moment, we’ll probably target somewhere like Ashland in far southern Kansas.

Link to pics from our Mexican storm day – mammatus from the un-chaseable storm and a photo of the cell on radar on the laptop…

http://macca.bsch.au.com/gallery/20070502

Link to pics of the developing monster supercell which went on to produce the Greensburg tornado…

http://macca.bsch.au.com/gallery/20070504

Link to pics from yesterday including two of the tornadoes (but not the nice stove pipe which we only have on video)….

http://macca.bsch.au.com/gallery/20070505

Macca & Chris

(Currently staying in Clinton, OK as lines of thunderstorms pass about 5-10mi to our west with the odd storm passing over us...we had a lightning strike the building across the road...sparks were flying and the thunder was awesome!)
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: David C on 08 May 2007, 07:18:59 AM
Excellent report and congrats on the tornadoes -- great stuff, although the flip side of it all must have been all too evident for you guys as you approached Greensburg that night. The DDC area has copped an absolute flogging from this system and the wording in some of those tornado warnings was just spine-chilling. In addition, at the time there was a velocity image posted on storm track showing the off-the-scale TVS (~150 knots total shear) right over town. Back in 2004 we were on a storm, in the general same area btw, that was visibly spinning like a top and produced an EF4 and that was up at around 112 knots. The point being, this latest storm (Greensburg) was just brutal, and was brutal for over 100 miles.
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jeff Brislane on 08 May 2007, 08:03:57 AM
Dave,

Could you post any links here of video or pics of good storms and tornadoes that you see on stormtrack.

Jeff.
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: David C on 08 May 2007, 08:16:25 AM
Hi Jeff,

try this first if you have not seen it.

http://www.youtube.com/watch?v=DNL7ASvl4k4&eurl=http%3A%2F%2Ftornadovideos%2Enet%2F
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: David C on 08 May 2007, 08:25:57 AM
Here's some more footage, this time from May 5 http://www.youtube.com/watch?v=roOVvEGyrzk
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Macca on 08 May 2007, 09:23:54 AM
Hi all,

Currently getting FLANGS galore but in between storms, I have just taken two screen captures (literally photos of the screen of my video camera) of the stove pipe tornado we got on Saturday night (last night).

http://macca.bsch.au.com/gallery/20070505

Enjoy,

Macca & Chris
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 08 May 2007, 06:58:03 PM
Hi all,

We have not been able to post for a few days because we have been on the road since acquiring the second vehicle.

First, congratulations on Macca and Chris for getting onto the tornado on the 5th May. We met them prior to getting those tornadoes same storm but we were destined to return to Dallas to pick up and set down friends in the group (arriving 3:30am). We did get two tornadoes and possibly a third daytime tornado - one was up close and personal within half a kilometre but not strong and no funnel developed. Impressive video as we headed on the go with rotating wall clouds etc.

On the night of the Greensburg, we were also cut off by the damage and on the way when the wedge was touching down, within 20 miles as the tornado ripped through the city and then as we headed up the 2 miles of downed power poles etc, Ray and Brad suggested they had observed a tornado consistent with the now smaller tornado direct north that did damage and cut off the northern road option. We will have to check video but low light made it difficult to observe. The scene of desctruction made us feel sick - for me it was the first time I was turned off by being in the area knowing there were and would be fatalities with a mile wide.

Yesterday was relatively crap though we had some blasting canon cg's in Clinton and that echoed across the whole neighbourhood for at least 10 seconds and vibrated the building!

Anyway, I will cut short here. Today is more like cold front central with likely HP supercells - lots of rain and thunder. We will play an easy day possibly along the red river rather than extreme SW Texas.

In relation to references to the supercell that hit Greensberg, I would like to add that this will go down as one in history as wedge fest. It is vary rare to get a cyclic supercell that puts down of the order of mile wide wedges one after the other. It was a long tracked supercell and one that prodcued tornadoes for at least 5 to 6 hours - I have not read up the reports at this point.

I will put some images online when time permits.

Regards,

Jimmy Deguara
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jeff Brislane on 09 May 2007, 03:10:33 AM
Dave, That is awesome video! Those guys a completely insane and that wedge is just frightening!
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: David C on 09 May 2007, 06:03:57 AM
Chuck Doswell seems to think so to Jeff!  see comments on this thread http://www.stormeyes.org/tornado/blog/archives/2005/08/appalling_examp.php

Diverting the thread slightly, these guys have obviously made it their mission to shoot dangerously up-close footage and, for quite young guys, the would be making a nice 'little' profit -- I know some cuts of quality newsworthy footage (not specifally these guys) have fetched around 30,000 US - of course this depends entirely on what you have / who else has similar and whether CNN etc want it. I have no problem about individuals risking their own lives....each to their own. A different story if your actions start putting others at risk.

Personally, when there are tornadoes on offer, I would always like to be somewhat close - say 0.5-1km although that depends on the situation. I would not have liked to have been within 2 km of the Greensburg monster at that time of night, in fact I rather not chase tornadoes at night at all.

Anyway good stuff Jimmy look forward to seeing your lp and the tornadoes.
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: VORTEX on 09 May 2007, 09:17:35 AM
Since I've been ill this is about as close as I get to chase...I was NOWCASTING for a couple of intercept spotters for a TV station....Here are some interesting radar images...One is the BWER from the debris..
[attachthumb=#]
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jeff Brislane on 09 May 2007, 02:02:42 PM
Dave,

If I was there i'd be looking to get within 1km of a nice f2 tornado like that one, allthough I'm not sure about 100m. I agree that as long as you only put yourself at risk than so be it and I would be bored if the tornadoes were always a couple of km away, unless of course there was good structure.

Some people do it for the thrill and not just the science. However that night time wedge is just frightening, what a beast! And what is it about night time wedges over there? They seem to be far more common than day time wedges.

Jeff.
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 09 May 2007, 06:36:39 PM
Hi,

Jeff, night time wedge in this case developed because the storm moved into a volitile environment after breaking the cap 3 hours or so before sunset. I can tell you there were relatively few chasers on the night time wedge supercell considering there were so many chasers out and about.

Anyway, after the Clinton lightning and rain, we chased yet another tornado warned supercell. We actually booked the hotel in my target region and the storm came towards us so a relatively short chase (thanks to Macca for alerting me and getting me excited haha). We then headed after it. Canons and power flashes hammered the area near the US 75 border area of Sherman - nice green glows. Of particular interest at the time rotation was being detected there was a prolonged green glow of 5 seconds over about a 100 metre spread or more. This did not coincide with a lightning strike from our perspective. It could have been straight line winds of course but worthy of note.

There has been no rest for several days now.

Regards,

Jimmy Deguara
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Macca on 09 May 2007, 07:10:05 PM
In any given strongly unstable environment, the conditions are often more favourable for wedges after dark as the lower levels cool, the LCL height lowers, and thus not only does this increase the chances of tornadoes (alone), but it also provides for better conditions for wedge tornadoes.  It is also common here that the LLJ increases sigificantly during the evening/overnight (again providing another factor for increased tornadic activity after dark in a strongly unstable environment). 

I guess when you think about it, the lower the LCL, the less "wide" a tornado needs to be to meet the wedge definition (wider than it is high?).  So to have an LCL of just 200m (700ft), the tornado would (only) have to be 250m wide to meet the definition.  Certainly not a large tornado on the grand scale.   

Macca
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: David C on 10 May 2007, 03:53:41 AM
Yes, anecdotal at least, it does seem to me too that wedges are more common at night. In saying that when you are talking abut a 1+ mile wide tornado then all the standard tornado parameters would be at the top end of the scale. It is just a question of when the storm moves into a suitable environment, day or night. As you guys have said, the increase in the low-level jet (this possibly as 'inhibitory' vertical mixing decreases and / or due to baroclinicity via +ve west-east temperature gradient over the sloping terrain of the Plains) would be critical since this increases the low-level shear as well as maintaining ongoing northward advection of moisture (hence a lowering of LCL with nocturnal cooling). This could both intensify and in effect 'bring' the low-level mesocyclone closer to the ground - probably explaining any day/night bias in distribtion of strong violent (and large) tornadoes.

Anyway, good stuff from everyone over there, we are all enjoying the reports immensely back here!
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Macca on 10 May 2007, 08:40:40 AM
Hi all,

We have a few days to catch up on (I think) after the hectic 2 days in Kansas.  We are still yet to go through our videos of the Kansas outbreak/s so there may be more tornadic action yet that we aren’t sure about. 

On Sunday we left Hutchinson, Kansas and headed S.  There was a well defined surface (outflow) boundary lying from just east of Hutchinson, Kansas off to the WSW to near Woodward in Oklahoma where this intersected the front which was aligned nearly north/south along the Oklahoma/Texas border.  Warm moist air was present to the south and east of these boundaries and was being advected northward with a 25-30knt south easterly low level jet .  The upper trough (which was still sitting to the west) was providing for some nice mid to upper level speed shear with a 40-50knt mid level jet from the south (which proved to be problematic as you will soon read).  CAPE to the south of this boundary in western Oklahoma was increasing rapidly (into the 3000-4000j/kg range) as cloud cleared and heating took place.  Storms were ongoing from the previous night along a line from east central Kansas to north central Oklahoma.  As we were leaving the motel at about 11am, one of these cells to our south (near Medicine Lodge) became tornado warned after storm spotters reported funnel clouds.  We didn’t chase this cell as we wanted to target north western Oklahoma where there was at least some cap in place and convection had not yet fired. 

As we dropped west and south, 3 or 4 isolated storms developed further S and W along the line along the Tx/Ok border.  We entered Oklahoma and had decided we needed to get to Seiling for fuel before commencing an intercept on one of these storms (which were now only 20-30mi west, 30-40mi south west and 40-50mi south south west of us).  The storm to our west exploded as we were fuelling up and the inflow into this cell even from this distance was amazing.  The winds at the surface picked up from 15knts to 25-30knts with gusts of up to 40knts as this cell just opened up a nice hole in the cap and the warm, moist, unstable air just raced to it.  At the time, we didn’t realize that this cell was sitting on the intersection of the two boundaries otherwise we probably would’ve targeted it.  We did hear that it was tornado warned and was capable of producing hail up to the size of baseballs but it was looking slightly grungy on radar (with other showers developing around it).  We decided to intercept the next storm along the line to the SW so we pushed west and then South to Carmargo but whilst we were doing this, the areas between each storm started to fill in with new convection and by the time we reached Carmargo, we were now watching a line of storms with embedded supercells.  This is probably a result of weak capping.  We watched for a while incase any of the embedded supercells was able to keep it act together but to no avail.  There were quite a few other chasers around who were doing the same thing.  One small glimmer of hope was the southern end of the line…there were more cells down into north western Texas but there was a 20mi break in the line before those cells.  I think every chaser in the area had the same idea that maybe this semi-tail-end charlie might get the job done and soon every chaser and his dog was heading south towards Leedey for the intercept.  We got there and headed west to get closer and it looked ok for a short period of time as an RFD wrapped up a weak wall cloud but it rapidly gusted out.  That was pretty much game over unless you wanted to drive another 150mi south to get on the southern end of the next line coming up.  We called it a day in Leedy at about 6:30pm and headed south and east to Clinton, Oklahoma where we stopped for the night.  With the line of storms to our west extending way way back down into south western Texas, we figured we’d at least get a decent lightning show as it pushed slowly eastwards.  Individual cells were moving NNE but the whole line slowly progressed east and we were treated to a great train-effect lightning show which went from about 8:30pm through to about 2am when the last storm of the line finally passed over us.  It started off with mostly in-cloud flashes with a ratio of about 1 CG to 50+ in-cloud flashes…then while we were sitting in our room there was a MASSIVE flash (that’s all I saw).  Chris was looking out the window from his bed at the time and saw the CG hit something across the street (about 100m away) and saw the sparks flying everywhere afterwards.  We both crapped our pants as the thunder was instantaneous (we were at or very close to the maximum thunder volume distance).  After this, the storms started to produce some AWESOME CG’s which hit all over town around us on and off in barrages of 10-15 minutes for the next 3 hours.  Just as we thought one lot was over, another would start coming up from the SW and within 10-15 minutes it was on again.  We had countless strikes within 1.5km and although I took about 300 frames with my digicam (all short duration due to the hotel lights), I didn’t manage to get 1 CG…haha.  We got plenty on video though ?. 

Yesterday, we knew it would be very marginal so we had a very casual day to relax from the craziness that had been the past 3 days.   There was a very slight chance that a storm would kick up on a weak OFB that was sitting right along the Red River (Tx/Ok border).  Weak instability was pushing westward behind the previous night’s MCS as easterly flow returned to the west as a result of the upper trough STILL sitting off over the four corners region.  We dropped S from Clinton, OK to Vernon, Texas where we checked some data and realized that the chances of anything going up would be better slightly further east where a weak low had formed on the red river near Wichita Falls.   So that became our destination.  We checked into a motel and kept our eye on the radar and by 6pm a small area of storms developed about 70mi to our east and was moving NE.  This is the stuff Jimmy got on to.  From reports I’ve read, it became briefly supercellular, produced some near-golf-ball hail and was tornado warned for Doppler indicated rotation (but never produced).  We decided not to chase as it would’ve put us over 100mi from Wichita Falls and we really needed a break. 

Today was a really relaxing day for us and it want from being just that to being an AWESOME chase in the space of 2 hours – over here, they call these days “sleepers” where no one really expects massive fireworks but then it turns out to be really good!.  We stumbled out of bed at around 10:30am to check the forecast charts.  No one was expecting much but I think everyone had their eye on the outflow boundary from the previous night’s convection over north western Texas which was draped WSW-ENE across Abilene to Dallas.  15-20knt ESE’ly winds at 850mb to the south of this boundary were being over run by 30-35knt SW’ly (just enough shear for supercells).  A N/S aligned line of cirrus was drifting across the boundary preventing much heating until after lunch but after that, heating took place nicely and the atmosphere began to destabilize.  We stuffed around all morning and kinda watched the sat pic and radar. SPC weren’t too confident in severe storms but had a 2% tornado chance and 15% hail and wind chance for the area just in case.  At about 2:00pm I was checking through the latest obs and SPC meso analysis data and noticed a nice pocket of moisture converging around the Abilene area.  With the heating and the moderate influx of moisture, CAPE values had gotten up to 3000j/kg over that area (interesting!).  A quick check of the sat pic showed an enhanced cumulus field in the area and within 30 minutes showers and weak storms were showing up on radar along the boundary from Abilene to N of Mineral Wells and the tops were getting up to around 40-45k feet. 

We casually got our things together and headed out the door and dropped S from Wichita Falls to Graham.  By the time we got there, two cells were looking the most impressive.  One NE of Abilene and one to our west.   We headed west from Graham with the thought in mind that we’d hit the Abilene cell as it was clearly looking stronger than the other one but as we neared the first cell which had moved just N of our west road, it produced a nice little wall cloud and a few nice CG’s.  We stopped to watch for a short while before we blew it off for the cell which was now nearly due W of us about 20mi away.  The first cell moved off to the N but maintained its structure but as we neared the main cell, we realized that this was the main show.  A nice low-hanging wall cloud was present as were mid-level inflow bands.  We kept heading west to get closer and eventually stopped in a clearing (there are quite a few trees in this area) and watched as this supercell rotated nicely as it ambled slowly due north.  Inflow from the east in the lower levels was clear and this cell had some fantastic structure for most of its life.  The wall cloud lowered several times and dragged along the ground for some time.  We videoed this and have since heard reports of some weak tornadoes with this – we’ll have to review the video to confirm but some of this “ground dragging” may’ve been one of these weak tornadoes (although it didn’t look to be rotating that strongly so who knows).  We moved further west and then north to sit just N of Throckmorton where we set up and watched this cell which sat just off to the west of us with its nice laminar structure.  It put down a nice RFD at this point but again we didn’t see any tornado.  We pushed a little further N as the cell put out what looked to be its last “cycle” (if you can call it that) as another RFD pushed out quite strongly and appeared to undercut the base.  We were fairly close to it at this point (<1mi) and were hoping it was going to put down a weak tornado but it didn’t. 

We let it pass off to the N and whilst taking a short break (2 mins) we noticed the line of storms we had been watching all morning and afternoon had really raced eastwards in the last few hours and was now merely 15mi to our west.  Soon a long low guster came in to view and it was flying along!  We dropped back into Throckmorton and were going to head east to get into a position to video/photograph this 4-layer guster but another isolated storm had developed ahead of the line to the ESE of Throckmorton and had blocked our east road option.  This guster was looking mean and green and we pushed east as far as we could without going into the isolated storm and we stopped for some video/pics of the guster.  This was all fine until one part of the guster took on a more base-like look appeared to be rotating rapidly and was racing right towards us.  Not wanting to take any chances, we decided we’d rather encounter some hail and heavy rain than get caught in front flank rotation.  So we punched into the rain from this cell (which was starting to look really nice on radar and was showing up 1.5 inch hail and 65dbz echoes at 20,000ft on wx worx).  We encountered a short barrage of pea sized hail and a handful of larger stones possibly up to 2cm before we broke out into the front of it…and what a sight!  This little storm had gone nuts.  For some reason, the air we came out into was significantly more warm and moist than we had had earlier in the day and this cell was just feeding on it.  A nice guster had developed on the front flank (NE quadrant) but the base was still evident on the south eastern quadrant and we stopped for a few brief photos of this near Newcastle.  It was looking really green and the lightning picked up rapidly with some CG’s striking out in front of it at this point.  We took off east for a bit to get ahead of it and about 3mi down the road, we stopped again for a look and it although it appeared to have a HP’ish look to it a wall cloud had developed under the base on the front flank in the notch.  It was rotating rapidly and it produced a brief stout cone-shaped funnel and we thought it was going to do the job but the funnel disappeared almost as quickly as it developed and the RFD that wrapped up the wall cloud pushed out and the cell became outflow dominated.  We had to move again at this point as the cell pushed out strongly towards us and was threatening to blast us with outflow and hail.  A gust of 76mph (122km/h) was reported just to our N shortly after this.  For the next 15-20 minutes we raced east and stopped and raced east and stopped to get photos of this now very impressive guster.  Eventually, the outflow pushed too far ahead of the rain and it weakened so we stopped in Jacksboro for dinner before heading back here to Wichita Falls.  250miles, 2 supercells and an awesome squall line later, we are back in our motel room fairly impressed at what we saw today given the low expectations.  Its amazing what can happen with some moderate instability and some decent shear.  There are two (possibly 3) tornado reports from the first storm we were on but as mentioned above, we did not see anything which screamed “tornado”.  The first storm report was from before we got to the storm but the others, we were there watching.  There were several interesting lowerings but at the time we didn’t think they were tornadic.  We’ll have to review our video but we were in a pretty good position for quite a bit of the time. 

Link to some pics from Sunday (Day 10)…

http://macca.bsch.au.com/gallery/20070506

Link to some pics from today (Day 12)…

http://macca.bsch.au.com/gallery/20070508

Macca & Chris

(*VERY* happy!)
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Michael Bath on 11 May 2007, 03:09:34 AM
Hi all - here are Jimmy's photos during this severe weather outbreak. Click on the links for the full set of images on each date.


Wednesday 2nd May (http://australiasevereweather.com/photography/photos/2007/jd20070502.html) Click on this link for all images

Extreme SW Texas south of Junction. Storm became tornado warned as basically a tailend charlie storm and remained surprisingly tornado warned for some time. We saw but did not film or photograph the rain slot trying to get better position. We then headed back east with it - you can see the squall line - very turbulent motions!

(http://australiasevereweather.com/photography/thumbs/2007/0502jd03.jpg) (http://australiasevereweather.com/photography/photos/2007/0502jd03.jpg) (http://australiasevereweather.com/photography/thumbs/2007/0502jd09.jpg) (http://australiasevereweather.com/photography/photos/2007/0502jd09.jpg) (http://australiasevereweather.com/photography/thumbs/2007/0502jd15.jpg) (http://australiasevereweather.com/photography/photos/2007/0502jd15.jpg)

Thursday 3rd May (http://australiasevereweather.com/photography/photos/2007/jd20070503.html) Click on this link for all images

We hung around Waco, Texas during the afternoon on this particular day. We left the mess of the tornado watch box in east Texas given conditions were still ripe and recovering in this region. Seeing a persisting weak cell visually and on radar, we headed north to intercept it. It looked rather weak - very narrow anvil. From the time We proceeded west towards the cell north of Hillsboro, Texas - the storm had intensified and developed a cow catcher structure, a crisp side anvil and dangerous anvil bolts. The lightning bolt action became a barrage lasting at least 5 to 10 minutes. We finally were able to find a good location to stop.

A wall cloud developed and finally the severe warning turned to a tornado warning. The whole scene was in high contrast with good time lapse from two video cameras. The wall cloud being up close seemed to either redevelop or perhaps I lost perspective being so close.

Finally we dropped south and the wall cloud NW of Hillsboro was rotating rapidly. The clear slot introduced a rain shaft but no tornado seemed to make contact.

The storm met a quick demise into the typical LP supercell shrink stage. It ws quite nice to see the inflow persist right up until complete obliteration.

A fantastic chase and no chasers around - just the pick up trucks.


(http://australiasevereweather.com/photography/thumbs/2007/0503jd05.jpg) (http://australiasevereweather.com/photography/photos/2007/0503jd05.jpg) (http://australiasevereweather.com/photography/thumbs/2007/0503jd12.jpg) (http://australiasevereweather.com/photography/photos/2007/0503jd12.jpg) (http://australiasevereweather.com/photography/thumbs/2007/0503jd17.jpg) (http://australiasevereweather.com/photography/photos/2007/0503jd17.jpg)



Friday 4th May (http://australiasevereweather.com/photography/photos/2007/jd20070504.html) Click on this link for all images


My friends and I were late to the tornado travelling along 160 when the tornado was crossing 183, and Greensburg, Kansas. Our target was SW Kansas and we remained in the area for some time at Anthony then met Macca and Chris at St Johns. We had initially moved towards cells erupting in eastern Texas panhandle and extreme NW Oklahoma and were just too late for those tornadoes and then headed north taking a bad road option (well the intent I guess under pressure was to intercept the storm near Pratt).

We were stopped amongst the very long damage swath along 183 near Greensburg, Kansas. I was sickened to think what it had done to Greensburg at this point given the extensive damage to power poles as well as a house. We headed back to Dodge City, Kansas and passed numerous emergency vehicles. The mood was one of sadness for the rest of the night.

I have checked video although at best I think besides stills of the structure, only one possible tornado on my images thus far. Brad has a very high possible tornado looking image - perhaps the new developing tornado?

Edit: Since this writing, Jimmy Deguara has documented images of the Greensburg tornado (http://www.australiasevereweather.com/video/thumbs/2007/0504jd144.jpg) (http://www.australiasevereweather.com/video/stills/2007/0504jd144.jpg)

More about the video stills are mentioned in this post:

http://www.australiasevereweather.com/forum/index.php?topic=424.msg3521#msg3521

(http://australiasevereweather.com/photography/thumbs/2007/0504jd19.jpg) (http://australiasevereweather.com/photography/photos/2007/0504jd19.jpg) (http://australiasevereweather.com/photography/thumbs/2007/0504jd25.jpg) (http://australiasevereweather.com/photography/photos/2007/0504jd25.jpg) (http://australiasevereweather.com/photography/thumbs/2007/0504jd34.jpg) (http://australiasevereweather.com/photography/photos/2007/0504jd34.jpg) (http://australiasevereweather.com/photography/thumbs/2007/0504jd44.jpg) (http://australiasevereweather.com/photography/photos/2007/0504jd44.jpg)


Saturday 5th May (http://australiasevereweather.com/photography/photos/2007/jd20070505.html) Click on this link for all images

Chased with Tim and Kay Marshall, The Eades couple and a few others in the crew. Intercepted a supercell organising and quickly developing a wall cloud in the rural areas SE of Greensburg and SW of Pratt, Kansas. There was a brief touch down up close and personal here. We then headed generally northeast and we noted at least 3 more brief touchdowns along the marathon trip north.

We then let this go and dropped south to the east of Greensburg, Kansas. We filmed an area of rotation and had lost contact with the crew. It was at this time we decided to to head back to Dallas - drop-off and pick-up. Luckily so, as we arrived well into the early hours of the morning. We off course hear the large tornado threat once more on the NOAA radio as we dropped south. Tim Marshall got a multi-vortex of one of the tornadoes.
(http://australiasevereweather.com/photography/thumbs/2007/0505jd12.jpg) (http://australiasevereweather.com/photography/photos/2007/0505jd12.jpg) (http://australiasevereweather.com/photography/thumbs/2007/0505jd34.jpg) (http://australiasevereweather.com/photography/photos/2007/0505jd34.jpg)
(http://australiasevereweather.com/photography/thumbs/2007/0505jd40.jpg) (http://australiasevereweather.com/photography/photos/2007/0505jd40.jpg)


Sunday 6th May (http://australiasevereweather.com/photography/photos/2007/jd20070506.html) Click on this link for all images

This was a basic let down - my target was Woodward, Oklahoma but we were unable to get to the storm on time so we opted for activity south. Nothing really happened and all south action collapsed. The Woodward storm went to produce tornadoes in Wichita County, Kansas. Of course we enjoyed the cannons lightning bolt and thunder combinations:)

(http://australiasevereweather.com/photography/thumbs/2007/0506jd05.jpg) (http://australiasevereweather.com/photography/photos/2007/0506jd05.jpg) (http://australiasevereweather.com/photography/thumbs/2007/0506jd16.jpg) (http://australiasevereweather.com/photography/photos/2007/0506jd16.jpg)


Monday 7th May (http://australiasevereweather.com/photography/photos/2007/jd20070507.html) Click on this link for all images

We were inside the core of the storm that began in Denton county and chased it northeast to Sherman. Made a wrong turn and missed the wall cloud. Some incredible lightning "cannon" and power transformer glows here. Now what was interesting was one transformer glow that lasted about 5 seconds over a few hundred metre length. Was it strong winds? It was near the shear region within the storm although can't tell exactly.

Had driven in hail to less than the size of golf balls in the core and torrential rain.

(http://australiasevereweather.com/photography/thumbs/2007/0507jd01.jpg) (http://australiasevereweather.com/photography/photos/2007/0507jd01.jpg) (http://australiasevereweather.com/photography/thumbs/2007/0507jd06.jpg) (http://australiasevereweather.com/photography/photos/2007/0507jd06.jpg)


Tuesday 8th May (http://australiasevereweather.com/photography/photos/2007/jd20070508.html) Click on this link for all images

We started out near Gainsville, Texas and then headed WSW towards Archer City. We then basically gave it a try to intercept the Throckmorton supercell but only could get in time for a cell developing to its east. This exhibited interesting behaviour as it became tornado warned. The wall cloud was visible to our SW and then a thick rain shaft rotated around the east side. Quite spectacular but the rian spoiled the show. A nice shelf cloud followed us back.

(http://australiasevereweather.com/photography/thumbs/2007/0508jd11.jpg) (http://australiasevereweather.com/photography/photos/2007/0508jd11.jpg) (http://australiasevereweather.com/photography/thumbs/2007/0508jd17.jpg) (http://australiasevereweather.com/photography/photos/2007/0508jd17.jpg) (http://australiasevereweather.com/photography/thumbs/2007/0508jd23.jpg) (http://australiasevereweather.com/photography/photos/2007/0508jd23.jpg) (http://australiasevereweather.com/photography/thumbs/2007/0508jd31.jpg) (http://australiasevereweather.com/photography/photos/2007/0508jd31.jpg)


We await the next decent system. Thanks to michael for preparing images once more.

Regards,

Jimmy Deguara
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Macca on 11 May 2007, 06:13:35 AM
FWOR!  Nice pics Jimmy!!!  Great to see how things looked from slightly different areas too!

We went on a very local chase here this afternoon.  Some moderately strong storms developed to our SSW late this afternoon and moved northwards towards us so we drove about 20mi south of here (Wichita Falls).  It pushed out a nice guster and some infrequent CG's.  It was moving at about 10mph (very slowly) and we basically followed it back to Wichita  Falls and let it run over the top of us.  It had some nice gusty winds and some quite heavy rain.  There is now a large area of thundery rain sitting over us with one flash every 3 to 4 minutes but no bolts  :( .  Here are some pics...

 http://macca.bsch.au.com/gallery/20070509

The next few days are looking very dubious (although so were the last two...hehe...but moreso over the next few days).  Tomorrow might be ok for some more thundery action as the upper low which has been sitting over the southern Rockies for the last 6 days finally moves off to the east (over us) but after that, upper level ridging looks to take ahold of the plains.  There are two stormy options to play with when this happens...one is to head east into the lower Mississippi valley which will be ahead of the upper low and will have ample moisture for some pulse storms.  The other option is to head up to the northern plains (Nebraska & the Dakotas) and play any upper troughs which ride across the top of the ridge.  There is quite a bit of moisture up there as well and I think most chasers who are on their "chasecation" during this period will take this option as the first upper trough looks to be drifting over the Dakota's Friday/Saturday/Sunday. 

Macca & Chris

[Edit:  Just as I pressed "send", a massive FLANG just hit about 300m away!!]
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Mike on 11 May 2007, 02:16:26 PM
Top stuff fellas!  Just great photos and 'commentary' of the past day's events.  The severe weather is getting plenty of television coverage here in OZ!  Certainly has been a fierce outbreak of tornadoes this season in the US.  Has been a pleasure to read your reports one and all.  probably makes it more exciting considering we aren't there to witness the storms!  Dang!

From viewing the WRFs there's still some stuff to come although some areas that had numbers like -8 LI's, CAPE 4000-5000 were stuffed up by mid to high level frontal cloud that really messed things up and wrecked any tornado formation.  Certainly some weak shear expected over the next day of less than 40kts in the low to mid levels but southern TX and parts of Oklahoma still looks inviting on the models.

Pity that developing low on the east coast is weakening, too much cooler water underneath!  wuold have been a doubleheader to head out there if that was strengthening to hurricane status!

Good luck and keep safe guys.  Enjoying the posts from you all!

Mike, Darwin.
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 11 May 2007, 06:46:50 PM
Macca and Chris,

The storms you have intercepted includig the night tornado are impressive - including the storm in Throckmorton county a couple of days ago! You have done well.

Hope we can meet up today for an Aussie, Slovenian, and Finnish BBQ. And of course some alcohol somewhere in there:) Be good to echange the current exciting moments!

We are still in Lindsay, Texas near Gainsville at the Lindsay Inn.

Regards,

Jimmy Deguara
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 14 May 2007, 05:04:16 PM
Here is an image taken on the 8th May 2007

http://www.australiasevereweather.com/forum/index.php?action=dlattach;topic=430.0;attach=878;image

Thread here:)

http://www.australiasevereweather.com/forum/index.php?topic=430.msg3232#msg3232

Regards,

Jimmy Deguara
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 14 May 2007, 05:30:36 PM
Hi,

Just so that people know this is the supercell that exploded and became a monster only an hour and half later to level Greensburg:

(http://australiasevereweather.com/photography/photos/2007/0504jd11.jpg)

(http://australiasevereweather.com/photography/photos/2007/0504jd13.jpg)

We were onto the other tornado warned storm that eventually collapsed so we raced north for this cell - the rest is history. The marathon catch up and finally move into damage path - 4 miles of damage along 183 - levelled house, tree branches, gas rupture and snapped power poles.

Regards,
Jimmy Deguara
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 18 June 2007, 10:32:47 AM
After two attempts at obtaining video stills, I have been able to further solve the confusing events of the evening, what was observed, and importantly, uncover a few probable sightings of the tornado based on video. The conditions were very difficult for chasing given we were late to the event and given the tornado (based on other chaser accounts) the tornado became rain-wrapped for a while only to emerge as it crossed and created more damage on route 283 north west of Greensburg. The video evidence of the probable tornado is consistent with this latter stage.

Also included are various images of the damage along the road, the storm structure and some of the lightning.

(http://www.australiasevereweather.com/video/stills/2007/0504jd144.jpg)

(http://www.australiasevereweather.com/video/thumbs/2007/0504jd008.jpg) (http://www.australiasevereweather.com/video/stills/2007/0504jd008.jpg) (http://www.australiasevereweather.com/video/thumbs/2007/0504jd028.jpg) (http://www.australiasevereweather.com/video/stills/2007/0504jd028.jpg) (http://www.australiasevereweather.com/video/thumbs/2007/0504jd075.jpg) (http://www.australiasevereweather.com/video/stills/2007/0504jd075.jpg) (http://www.australiasevereweather.com/video/thumbs/2007/0504jd162.jpg) (http://www.australiasevereweather.com/video/stills/2007/0504jd162.jpg) (http://www.australiasevereweather.com/video/thumbs/2007/0504jd174.jpg) (http://www.australiasevereweather.com/video/stills/2007/0504jd174.jpg) (http://www.australiasevereweather.com/video/thumbs/2007/0504jd178.jpg) (http://www.australiasevereweather.com/video/stills/2007/0504jd178.jpg) (http://www.australiasevereweather.com/video/thumbs/2007/0504jd181.jpg) (http://www.australiasevereweather.com/video/stills/2007/0504jd181.jpg) (http://www.australiasevereweather.com/video/thumbs/2007/0504jd182.jpg) (http://www.australiasevereweather.com/video/stills/2007/0504jd182.jpg) (http://www.australiasevereweather.com/video/thumbs/2007/0504jd184.jpg) (http://www.australiasevereweather.com/video/stills/2007/0504jd184.jpg) (http://www.australiasevereweather.com/video/thumbs/2007/0504jd187.jpg) (http://www.australiasevereweather.com/video/stills/2007/0504jd187.jpg)

(http://www.australiasevereweather.com/video/thumbs/2007/0504jd188.jpg) (http://www.australiasevereweather.com/video/stills/2007/0504jd188.jpg) (http://www.australiasevereweather.com/video/thumbs/2007/0504jd192.jpg) (http://www.australiasevereweather.com/video/stills/2007/0504jd192.jpg) (http://www.australiasevereweather.com/video/thumbs/2007/0504jd235.jpg) (http://www.australiasevereweather.com/video/stills/2007/0504jd235.jpg) (http://www.australiasevereweather.com/video/thumbs/2007/0504jd246.jpg) (http://www.australiasevereweather.com/video/stills/2007/0504jd246.jpg) (http://www.australiasevereweather.com/video/thumbs/2007/0504jd254.jpg) (http://www.australiasevereweather.com/video/stills/2007/0504jd254.jpg)

All video stills available here:
http://australiasevereweather.com/video/stills/2007/20070504.html

Regards,

Jimmy Deguara
Title: RE: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: David C on 18 June 2007, 01:38:09 PM
Fantastic mate - I knew you must have had something on video - also some good shots of the structure there!!
Title: Re: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Mike on 19 June 2007, 03:34:04 AM
Hell, those stills are so sureal.  No wonder tornadoes are so dangerous at night given those images.  Does the larger first pic show the tornado in the centre Jimmy?

Mike
Title: Re: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 19 June 2007, 06:46:57 AM
Mike,

Yes that image was the one I was looking for for confirmation (after some brightening) to show straight edges of a tornado still strong but not as wide as earlier in its life cycle. The images below the large one if you click to enlarge have evidence of the tornado behind the scud but not as clear as the enlarged image above. The tornado would have been in the previous images as well but wrapped in rain. Perhaps Brad can also upload his images showing the tornado. Brad and Ray suggest what they saw was a very large tornado - not sure if this is what they saw or something larger and earlier.

This collection of stills was one of the most difficult to deal with taking litereally hours to prepare but thankfully being David's camera it is as modern as it gets in terms of the quality (on the prosumer range).

In terms of chasing at night, yes it is extremely dangerous and is one of the reasons the local sheriff lost his life - not sure what were the details but perhaps he misjudged the tornado's size trying to use the lightning flashes as a guide to where the tornado was. Anyone have details to cofirm this? In general, if a tornado is approaching and relatively close, it becomes very difficult to judge or even observe the tornado if you had not been observing the tornado in the first place. Further, on approach to route 283 SW of Greensburg, the tornado was smaller and then became larger. So even if the tornado was observed earlier, repositioning can easily make you lose perspective.

Now back to the topic.

Regards,

Jimmy Deguara
Title: Re: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 01 July 2007, 09:45:20 AM
I guess those that cannot view the Stormtrack forum, I felt given the spectacular nature of these images, and showing the enormous size of the tornado, I would include them here:

(http://img.photobucket.com/albums/v674/funky_mike/EF5.jpg)
(http://img.photobucket.com/albums/v674/funky_mike/EF5-2.jpg)
(http://img.photobucket.com/albums/v674/funky_mike/EF5-3.jpg)
(http://img.photobucket.com/albums/v674/funky_mike/EF5-4-1.jpg)

Photographs copyright by

__________________
mike scantlin

Link my blog and I will gladly return the favor.
http://mikescantlin.chaseblogs.com
Title: Re: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Mike on 02 July 2007, 03:42:39 AM
Are you kidding me?  That thing was huge.  Anything that fills the camera frame is just plain scarey.  Tell you what, you guys have done pretty well considering you could have encountered a lot more danger.  Great work.

Mike
Title: Re: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 02 July 2007, 04:18:12 AM
That massive wedge was hidden in rain by the time we got to it but I am possibly thinking the edge may be visible on one of tehe video frames I had posted hard to tell.

This was an incredible chase particularly for those who saw what is presented in these images.

Regards,

Jimmy Deguara
Title: Re: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 02 July 2007, 10:37:09 AM
Just tracked down the tornado emergency warning for Greensburg that we heard on the Noaa radio:
-----------------
SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE DODGE CITY KS
941 PM CDT FRI MAY 4 2007

KSC097-050300-/O.CON.KDDC./O.CON.KDD/O.CON.KDDC./O.CON.KDDC.
KIOWA KS-941 PM CDT FRI MAY 4 2007

…A TORNADO WARNING REMAINS IN EFFECT UNTIL 1000 PM CDT FOR CENTRAL
KIOWA COUNTY…

…A TORNADO EMERGENCY FOR GREENSBURG….
AT 937 PM CDT…NATIONAL WEATHER SERVICE METEOROLOGISTS AND STORM
SPOTTERS WERE TRACKING A LARGE AND EXTREMELY DANGEROUS TORNADO. THIS
TORNADO WAS LOCATED 5 MILES SOUTH OF GREENSBURG…MOVING NORTH AT 20
MPH.

A VIOLENT TORNADO WAS ON A DIRECT PATH FOR PORTIONS OF GREENSBURG…
ESPECIALLY THE EASTERN PORTIONS OF TOWN. TAKE IMMEDIATE TORNADO
PRECATIONS…THIS IS AN EMERGENCY SITUATION FOR GREENSBURG!!

A TORNADO WATCH REMAINS IN EFFECT UNTIL 200 AM CDT SATURDAY MORNING
FOR SOUTHWESTERN KANSAS.

LAT…LON 3749 9936 3745 9929 3760 9901 3764 9936

------------------
This is when I went ballistic - I knew people were most likely going to get killed. It was a warning like no other I had heard in my storm chasing career! Even reading it now sends a shiver down my spine.

Here is a link to the account from the duty forecaster that night in the Dodge City office

http://www.underthemeso.com/blog/?p=364

Blog and website by Mike Umscheid - Duty Forecaster at the Dodge City National Weather Service Office.

Regards,

Jimmy Deguara
Title: Re: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 23 July 2007, 08:03:09 AM
Hi,

Here is another view of the Greensburg tornado monster (http://kotv.com/newsimages/214/5beb8a57-1b53-4ca2-bb0f-8d9e78249169.jpg)

(http://kotv.com/newsimages/214/5beb8a57-1b53-4ca2-bb0f-8d9e78249169.jpg)


http://kotv.com/news/national/story/?id=126697

(http://www.weatherusa.net/blog/files/20070506/ef5_tornado_kake.jpg)
http://www.weatherusa.net/blog/entry.php?id=49

Regards,

Jimmy Deguara
Title: Re: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 23 July 2007, 08:23:18 AM
And now for some nice lightning and supercell structure of the Greensburg tornadic supercell:

(http://www.floridalightning.com/files/Greensburg_KS_Supercell.jpg)

(http://www.floridalightning.com/images/Greensburg_Wedge_Tornado.jpg)

Courtesy of Florida Lightning  http://www.floridalightning.com  BY MARTIN KUCERA


Regards,

Jimmy Deguara
Title: Re: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Mike on 23 July 2007, 07:51:12 PM
Jimmy. would you rate the Greensburg supercell as the scariest you have witnessed given what we know now and what you knew at the time of chasing it?  The photo of it just beggars belief.

Mike
Title: Re: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 22 September 2007, 04:07:24 PM
Hi Mike,

Sorry to not get back to you on your question. Yes this specific storm chase was one of frustrations and emotions. It was a massive event and I guess we were amongst it a little late of course to see the massive wedge but I know most other chasers were not even near the storm! That made us as a team feel that we had achieved something on this event. The video stills listed in this thread also confirmed what the guys Brad and Ray were seeing. The chase was one hell of an emotional roller-coaster ride.

http://australiansevereweather.com.au/storm_news/2001/docs/200105-04.htm (http://White Deer 29th May 2001) still ranks as the top chase being it was in the day time and we traversed with the whole time and were relaxed. It was also our first big tornado and in our first year in the plains - certainly an eye opener.

Getting back on the topic of Greensburg, the following link sent my Andrej Matko from this forum and also who came on the trip is a sensational image! It shows satellite tornadoes around the large developing tornado!

http://iatse354.com/354/Chases/Gburg/pages/0041.htm

(http://iatse354.com/354/Chases/Gburg/images/0041.jpg)

Regards,

Jimmy Deguara
Title: Re: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Andrej Matko on 22 September 2007, 09:25:57 PM
I see Jimmy already posted this image. I found it on the Stormtrack forum in a thread Andrea Griffa started to gather Greensburg tornado images. What shocked me the most were these images (video captures) that are showing satellite tornadoes. This particular capture is in quite good quality and resolution and shows the all three tornadoes very clearly. Amazing stuff.

I guess the conditions were extremely dangerous for chasing. These satellite tornadoes can easily catch you off guard, and they seemed to be quite some distance away from the main circulation. In places where you feel save...

What I also find interesting is the lowering/bulge on the left of the tornado. What do you guys think about it? Is this the "add-on" to the existing tornado, maybe two circulations that joined? If you check the images when the tornado was full-blown wedge, you won't see it anymore. For instance, if you would draw the line from where the bulge ends to the ground, I think you would get the shape, tornado had later in the development. Actually, I think this images show exactly what I have in mind. :)

Plenty of rotation everywhere. :)
(http://iatse354.com/354/Chases/Gburg/images/0019.jpg)

Almost joined...
(http://iatse354.com/354/Chases/Gburg/images/0020.jpg)
(http://www.ounhat.com/index.php?spgmGal=May_4_2007&spgmPic=5#spgmPicture)

And the result...
(http://iatse354.com/354/Chases/Gburg/images/0023.jpg)

This supercell truly was a multi-vortex (multi-tornado?) beast.
(http://iatse354.com/354/Chases/Gburg/images/83.jpg)

I guess this trucker didn't have a slightest clue about what just missed him.
(http://iatse354.com/354/Chases/Gburg/images/0053.jpg)

Check the rest of images here --> http://iatse354.com/354/Chases/Gburg/index.htm(http://[attachimg=#])
Title: Re: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Mike on 23 September 2007, 04:44:36 AM
After viewing those photos Andrej i think they could be suction vortices around the main exterior of the visible funnel in different stages.  Although it's not uncommon to have several funnels, perhaps the one on the LHS was progressing towards being a funnel but did not eventuate, the one on the RHS def looks like a suction vortice.  You can also see in the second last photo a suction vortice hidden within the funnel.   Any others got views on the question?

(I don't like the digital enhancement at all!  Perhaps it's to protect the image from those who may pinch it....)

Mike
Title: Re: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 23 September 2007, 06:18:41 AM
Mike,

Can you lead me to your source of information regarding suction vortices and satellite tornado differences.

I would say this has a suction vortice:

http://iatse354.com/354/Chases/Gburg/images/0020.jpg

Regards,

Jimmy Deguara
Title: Re: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Mike on 23 September 2007, 07:16:34 AM
Too many sources to remember ! - I've just read a whole lot on them through websites and from other articles found online and browsed.  This video of Dr Greg Forbe's explanation during a large tornado which showed three suction vortices is here:

http://www.weather.com/multimedia/videoplayer.html?clip=2635&collection=topstory&from=vid_brws2&tab=3&nav=84

I also read a while back on Fujita's theory on suction vortices (Fujita T, 1981, Tornadoes and downbursts in the context of generalized planetary scales, Journal of the Atmospheric Sciences, 38[8], pages 1511-1534.) and also his theory after he got hold of that amazing 35mm tornado film from the Xenia event.

 I understand that satellite tornadoes form next to the original funnel and then dissappear only to reappear on the other side (circulating per se) and that suction vortices are as a result of the separate wind flow vortices turning anticlockwise and clockwise next to each other within the thunderstorm and that the separate vortices usually are seen in the storm's dissipating stage, but initially the funnel can actually contain more than one vortex but co-joins to create the main funnel when at the mature stage and what we see once grounded.

I remember seeing a wonderful computer animation of wind profiles within a supercell and you think I can find it again?  No!  I'll hunt it down and post the link.  It's the best i've seen and the amount of wind direction, vorticity and inflow/outflow profiles blew me away. Air is not just sucked in and blown out - it's litterally blown apart and dispersed to all regions of the storm!

Just found one of my printed resources - it can be found at http://docs.lib.noaa.gov/rescue/mwr/098/mwr-098-01-0029.pdf  It's 45 pages long in PDF form but it is Fujita's assessment on the 1965 Palm Sunday tornado outbreak. He gives explanations and theory on suction vortices and the like.... It's Fujita - what more can one say.


Mike
Title: Re: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Jimmy Deguara on 23 September 2007, 07:49:26 AM
Mike,

Quote
I understand that satellite tornadoes form next to the original funnel and then dissappear only to reappear on the other side (circulating per se)

Do you think it is as general as this?

My main issue is that you corrected Anrej in saying that all were suction vorticies or am I mistaken? I would have thought that a funnel reaching the ground would be classed as a tornado and that being it circulated around the major vortex is a satellite tornado. However, I have not sourced definitions myself. So I could be wrong.

Regards,

Jimmy Deguara
Title: Re: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado
Post by: Mike on 23 September 2007, 08:25:31 AM
No, i wasn't correcting him, just making an observation of his question.  I'm not saying that all were suction vortices, but I was working out what the 'buldge' was that Andrej talked about.

 If it is a suction vortice did it dissipate or did it form with the main funnel ? Hard to tell by one or two photographs and without video to see where it went.  I'm not too sure of the sizes that satellite funnels get but that they do spin around the circumference of the main funnel grounded and in opposite direction to it also.

 So yes, I agree re satellite funnels/suction vortices are classed as tornadoes.

If the suction winds are present right around the main ground zero funnel and also present within the area of this region then yes you would have either one visible.  I would hope that it's not as general as this because there are so many dynamics (kinematic?) causing other things to happen around this area of interest.

There has been some discussion as to whether these things are actually tornadoes - but as a direct result of wind vorticity and of the storm itself they surely must be classed as tornadoes - even if they don't touch the ground.  I don't believe that you have to see it grounded to class it a tornado - the storm is producing something only when certain criterian are met right? 

From the photos it looks like on the LHS it could be a parent vortex but did not form and on the other side a satellite - but who knows - without the footage none of us can judge it's movement during the tornado phase!  Does that help?

Mike