Author Topic: April 30 to May 8, 2007 - Including the Greensburg Kansas EF5 Tornado  (Read 56517 times)

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Offline Jimmy Deguara

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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
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Offline Jimmy Deguara

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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
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Offline Jimmy Deguara

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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
« Last Edit: 02 May 2007, 04:57:05 AM by Jimmy Deguara »
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Offline Jimmy Deguara

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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
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Offline Macca

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Offline Macca

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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

Offline Jimmy Deguara

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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
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Offline Michael Bath

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Interesting right mover south of Brownwood Texas after 5pm. Wonder if any of the tourists are on to it !





EDIT: is it a right mover ?  Almost stationary with backbuilding
« Last Edit: 03 May 2007, 03:23:59 AM by Michael Bath »
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Offline Macca

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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

Offline Macca

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Offline Jimmy Deguara

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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
« Last Edit: 03 May 2007, 09:35:24 PM by Jimmy Deguara »
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Offline Macca

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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

Offline Michael Bath

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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)




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Offline Macca

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Offline Macca

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