Author Topic: VIC/NSW Thunderstorms ( incl Victorian tornado discussion ) 9 - 12 February 2010  (Read 35874 times)

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Offline Jimmy Deguara

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Hi guys,

Sorry about my persistence here. I am just trying to make sense of the whole thing - the way the photographs are pointing, the alignment of the damage path, the height of the bases the types of structures. You guys have flooded us with so much information it is hard to keep up. I am sometimes wandering if that is why it is quiet in this thread - I mean we are talking tornado here!

Can you guys annotate the photographs indicating:

- the "large circulations"
- the tornado
- the damage path

Further to this, can you give us some exact comments from someone like Harald Richter in regards to the comments of the tornado and radar analysis. Yes I know it is a lot to ask but it will go along way to clearing a lot of what is going on in my head and my lack of experience with the mention of low topped supercells and tornadogenesis.

Regards,

Jimmy Deguara
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Offline Richary

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I guess some of us have been quiet despite following the thread because I haven't seen any obvious tornado touchown captured on the camera in the photos supplies so far (despite their being some fantastic structure and so on). I agree the damage evidence would suggest tornado damage based on my two experiences, one being near Naracoorte SA the day after an evening storm went through, and having the chance to check the damage on the Adelaide (Noarlunga) tornado that I also got to check out the day after last year. Probably hoping for some more nice funnel photos with them actually on the ground.

That said it is a fantastic chase report and some very in depth analysis happening here that I understand takes time because of the analysis that is being done. Instead of just photoing and moving on, I appreciate the effort to analyse what happened.

Offline Jimmy Deguara

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John,

Quote
I would like to point out once again to anyone who believes that we are jumping at shadows that we have images that when contrasted show the likely Avenel touchdown, and many others....what we intially claimed (2 tornadoes) is far below what some might claim given some of the imagery we have...Brad and I desire to ensure we can verify each and every tornado as we go. Note that the current confirmed tornadoes tally stands at 5 individual tracks (not just photographed....you can see that in the pictures above a massive question for us is how many individual tornadoes are there....for instance...are the tracks we have identified thus far individual tornadoes or simply swathes of multiple vortices?...

Just post whatever higher quality or contrasted images you have with name plasted all over it of the actual tornado(s) where the funnel or bowl lowering below the base points to a circulation on the ground and annotate them. Also post some video of the rotation with the funnel/base/dust. I can assure you that I have video taken in poor lighting of dust and you clearly see rotation even at 110km/h and no tripod or stabilizer!

Are you able to post one image of the large cicular base please? There are not only one - but two of you that could assist each other? Storms have stopped all around - so more time in hand. I am asking for the text to picture ratio to decrease please. Also, post some video as that would at least reveal the major rotation being described here.

John, what is the separation distance between damage paths before a tornado can be classified as a separate tornado by definition?

A question in relation to the bridge and embedded grass - could flash flooding have been responsible for this? You talk about ample rainfall in the area.

In response to your claims that Bendigo has more tornadoes than this region thence the reasoning that people were not really expecting this - how do we know? Do we have sufficient data to support such claims? Schofields where I live has two tornadoes associated with it in the Bureau database and I doubt it is a tornado hotspot!

The most extraordinary component is the alignment along the road and railway track - bizzare. Note there is a kink of the road on the map. Can you trace the path of the tornado track on it please?

Quote
As Harald commented, what we observed was the absolute minimum to produce tornadoes, and the edge of supercell development...which makes it a very good example of why you need to be careful in TS forecasting.

I will message him privately about his thoughts.

One last thing, I will assume that I have permission to post the link of this thread for some US chasers/tornado researchers to see such Doswell and Davies et al who could provide some valuable comments and input into this bizzare situation?

Regards,

Jimmy Deguara
« Last Edit: 17 February 2010, 02:10:46 AM by Jimmy Deguara »
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Offline David C

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The images above are of a gustnado. Jimmy can you post to CFDG and have this confirmed (or otherwise).......
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Offline James

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Hi Brad/John,

Firstly can I say what a great analysis you have written up so far on the event. Very detailed, you can tell a bit of time was spent preparing this. Some nice structure in the photos provided so far as well.

I'm with Jimmy here in regards to seeing the higher quality images you have and or video. Those 3 images you have put up are nice however look to me like outflow with possible gustnados on the edge. The clouds above looks a little messy, what you normally find with outflow. The last picture seems to show the leaning developing cumulus you find on the outflow flank as the cool air underneath pushes out forcing warm moist air upwards. There is even a little circulation wave on the left of the cumulus normally associated with outflow in picture 3.

I should also say the reception has been typical from any non-victorians (Jimmy excluded, mostly in other places)

My comments/thoughts above would have been posted had you been living/chasing in NSW, QLD, NT, Oklahoma etc etc. It's not the location of where the photos are that I base my comments on, it's what's in the actual photos themselves.

Well done on some great chasing. It's good to see people making the effort and heading out and you've certainly captured some great images.

Offline Jimmy Deguara

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Hi John,

Please note down the reference to these definitions and are they related to the <5km storm height supercells you refer to? Are you suggesting that the gustnadoes are ingested into the main mesyclonic circulation in this case? What point are you trying to make in relation to your situation?

Quote
a US chaser would barely blink on a day like this...certainly wouldnt bother chasing, I therefore suggest we ask the experts...not chasers who may ignore an event like this

I think you are misjudging US chasers here. Unlike Australia, NWS researchers are also storm chasers in some cases. A tornado is a tornado and anything that resembles a tornado is mentioned as such and are not discounted I can assure you in tornado statistics. The dynamics that form them are a point for discussion. What you are trying to do here is create the massive discussion of text without providing sufficient evidence to back up the discussion visually. We are extremely confused and I in particular somehow cannot see a tornado personally even with the contrasted pictures. Please annotate them.

You mention about lack of time? Spend more time annotating the dynamics and less time writing these tedious posts!

Regards,

Jimmy Deguara
« Last Edit: 17 February 2010, 01:19:45 PM by Jimmy Deguara »
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Offline Jimmy Deguara

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John,

Quote
Tedious is the amount of posts that have been made questioning, making unfounded categorisations in ignorance of the large amount of evidence presented here

Where is the ignorance? In a scientific forum if you make a claim it is up to you to support the claim. You are the guys who saw the tornado so please get to the point of providing sufficient evidence. And don't worry I know about definitions of tornadoes.

I can assure you sufficient researchers have been notified but the shear volume of information may just be too much here.

Regards,

Jimmy Deguara
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Offline Macca

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Hi all,

Its an odd feeling (for me) to hear that some chasers in Victoria have bagged several tornadoes.  First thoughts are "why the hell did I move to QLD...I have been here for 4 years (read: seasons) now and have not seen one and if I stayed in Vic I could've seen this".  Second thoughts are "I should check the set up cause I can probably learn something". 

I remember flicking through the GFS and MesoLaps charts on the day and thinking to myself in the morning "there should be some nice storms around today.  Shear is decent, instability is nice, but there is no cap and it looks like the trough is going to surge eastwards as storms develop and push out some decent outflow".  Also during the day, I kept an eye on radar given that my parents live in north central Vic.  I remember thinking to myself "gee...this is nothing special...bit of a shame really" so I was quite surprised to hear reports of multiple tornadoes.

I also remember opening the forum to read the reports of the tornadoes and to see the pictures and saw Michael Bath's post with the GFS analysis charts.  My thoughts..."Wow.  The shear on those charts is pretty nice.  Imagine what could've been had there been deep, isolated convection". 

Then there was the detailed analysis from John and his discussion with Harald Richter.  I found it odd, to say the least, that there was mention of low-topped supercells with tops of about 15,000ft which had produced multiple tornadoes - some things weren't adding up (apart from the fact that the Yarrawonga doppler is starting to reach the upper end of its range at about 100km). 

Then there was the first few photos.  Photos showing what look to be outflow features and cloud bases at or near 5000ft (pretty likely given the obs ahead of the storm/s was 33/16 as per several BoM AWS's in the vicinity).  The whole adding up thing was getting more confusing. 

With bases of 5000ft and tops ot 15,000ft that only leaves 10,000ft of actual updraft to generate strong enough rotation to spawn several tornadoes.  Now I would think that this may only be possible in the case of some extreme updrafts.  So...how unstable was it?  Not *that* unstable.  "Low CAPE" as per John's description.  Could the stretching of the updraft come from extreme shear (as opposed to extreme instability)?  Probably not.  With bases of 5000ft (lets say 850mb) and tops of 15,000ft (lets say 500mb for ease and conservatism) and looking at the GFS analysis charts posted by MB, we have northerly winds of 30-35knts at 850mb and north westerly winds of 40-45knts at 500mb.  So really only 10knts difference between the two - not a huge amount of stretching going on here from shear (speed).  Note that directional shear isn't overly useful in these situations - more on that in a separate post if people want me to go into it.

So no extreme CAPE, no significant speed shear...so where is this coming from? 

My thoughts after reviewing ALL of the posted photos, reports, obs and data in quite a bit of detail...

I believe this to have been an outflow event.  With the strength of the winds in the lower and mid levels, it wouldn't take much to drag these winds to the surface and generate some strong outflow.  Couple this with some decent moisture (by Victorian standards), and you have some nice lowish outflow features (as shown in the pictures).  Push this outflow across some slightly variable terrain and you have great potential for gustnadoes. 

I chased a similar event (slightly further north) back in November 2003 which saw some strong outflow winds of up to 100km/h kick off some gustnadoes which I estimate had winds of up to and possibly more than 140km/h.  I watched one of these significant gustnadoes (dust up to 500m in the air) hit a single tree in a paddock and the tree was reduced to a mess of mangled stumps with the branches thrown 100m up in the air and they came down at least that distance away from where they were previously rooted. This gustnado persisted for approximately 2.5-3km (which didn't take long as it was moving at 80+km/h.  Photos of the chase (not the gustnado - was driving at the time) here (base levels and lowerings not dissimilar to Brad/John's photos)... http://macca.bsch.au.com/gallery2/v/Chase-Season-03-04/20031120/

Whilst I don't doubt the claims of sizeable ground level rotation, what I beleive is that these were gustnadoes - and some pretty strong ones at that.  The damage photos indicate winds of up to and probably in excess of 100km/h. 

This shouldn't take anything away from Brad and John who had one of the best chases in Victoria in recent times.  To get that close to a strong gustnado and to get photos and video AND do damage assessments and observations, etc is certainly highly impressive (and given the complete lack of decent storms up here in recent times, I'd take it for sure).  I really hope that this doesn't discourage anyone from posting reports or thoughts on this forum as this is what it is all about - seeing, reporting, analysing and concluding.  What is important about these events is that there is this significant level of post-event analysis done to ensure that the correct outcome is reached - and in this case, I think it has been.

Macca

Offline Jimmy Deguara

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John,

You have jumped the gun in suggesting people are saying you are lying. This is about trying get a correct outcome as Andrew suggests in the above post. I believe even before posting the first post on this event it appears you knew this was going to happen. What has happened is that instead of asking others to give some input, you have gone outright and suggested definite tornado and the scenario in play. Could it be a gustnado I mean seriously can it be ruled out? I have seen and chased this type of setup a few times and even whilst on the phone trying to make sense of what was going on and I was not making any judgement - this type of outflow dominant scenario is what was crossing my mind. The photographs did not in any way veer from what I had anticipated. I saw gustnadoes as well on most if not all the cases I have mentioned NOTHING as strong as what is being suggested here.

However, instead of jumping the gun I have personally allowed the discussion to continue some days now to allow for the evidence to be forth coming. As Macca says, this is a great example of gustnado behaviour. If there was a connection, you would see some sort of funnel dipping from the cloud base.



Is this a tornado?

http://www.australiasevereweather.com/video/movies/1999/1122jd01.wmv

At the time, I presented without any experience in the field despite chasing for the past 6 years at the time as a tornado. David Croan at the time came out and suggested gustnado. I did not argue the contrary. I had to accept from someone who had researched far more in severe weather meteorology. This is not to take away from a great observation from a very large storm.

As to the Clyve situation, what I commented at the time from memory was on the wedge status - yes again! Anyway that is cleared when sufficient photographs were passed across, I become more convinced.

I think Andrew MacDonald explains very well his thoughts and suggestions. Perhaps it could be adopted in this case. Perhaps not. But please have an open mind - we have.

Regards,

Jimmy Deguara
« Last Edit: 17 February 2010, 03:06:21 PM by Jimmy Deguara »
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Offline Brad Hannon

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Hello everyone.....and there's probably quite a few reading this I would imagine  ;D

Firstly I dont have the met knowledge or enough experience to enter into any 'absolute' discussion about this event, and I dont pretend to.  Those of you who know me would agree thats my usual approach I would hope.  Therefore I base my communication of storm chasing and my opinion based purely on obs of storm behaviour at the time and then photo/video later.  I may not have the scientific explanation for a particular event or feature but I consider myself a good judge of storm behaviour on the fly and I've been lucky to see a lot of impressive storms and tornados in the US - thanks Jimmy and Macca.

Therefore, I hope with all due respect to those who have much more theoretical and field knowledge and experience than I, that with more photos (including high-contrast comparo's) and video (which I will put up when I get a cable) although its not very helpful, the assessments may swing back toward this being a tornadic event with, if anything possible gustnadoes on the forward flank. But, personally, I have always considered gustnadoes NOT to be connected to cloud base - perhaps I am wrong. 

With all due respect, the dynamics of what was happening embedded in the murk that we now know is the direction of Avenel (hopefully the pics will show you) and also on the emerging forward flank later was, in my limited but increasing experience not primarily gustnado and I would hesitate to say not gustnado at all.  I did not see one vortice that was not connected to cloud base and outflow or not it seems to make no difference the way I see it, especially if the vortices are connected to cloud base.

Finally, just to ensure everyone is clear - there was a lot of evidence to the naked eye that this storm was exhibiting areas of distinct rotation and rapid development of very low bases and possible tornado a long time before the storm got to Longwood.  I think the photos combined with the damage path support this.  I'll do my best to get them up tonight but I have 2 (yes two!) sick kids and a grumpy wife at home so no promises :o

Regards,
Brad.


hmmm June 2nd......

Offline Jimmy Deguara

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Hi guys,

To add to the discussion, I post a very informative web page. A lot can occur within any storm supercell or non-supercell:

http://www.stormeyes.org/tornado/faq/notahose.htm

Brad, we are looking forward to whatever you can provide to assist in this ongoing investigation. I hope unlike John, you are not too frustrated. It is a discussion after all.

Regards,

Jimmy Deguar
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Offline Macca

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I'll reply in more detail tonight (it'll take me a month to read John's latest post) but if there are any more conclusive photos, now would be a VERY handy time to post them...poor contrast or not.  It is VERY had for anyone to conclude otherwise if there is no further evidence of tornadic activities.  Not saying that there is not, i'm just saying put the bloody things up so we can see them!

One thing I'll note immediately.  Temperatures and DP's in the area where these storms moved into during the afternoon were in the vicinity of 33-34C and 16-17C respectively.  Not overly high even for Victorian standards. 




Offline Jimmy Deguara

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Hi John,

Quote
once a storm becomes outflow dominated it dies

I am not so sure about this - not always. They could become elevated and very disorganised but not necessarily die. I would have thought that when outflow cuts off inflow is when a storm dies.

Quote
Well...its like me coming out and saying...well the Dunoon tornado was actually a remarkable gustnado?

You can certainly welcome to go to the Dunoon tornado thread and suggest so if you so wish. I have even had one person come to me and suggest "Was it actually a tornado?" I explained my reasoning and then it is up that person whether they wish to differ in opinion. He accepted it.

Can I see the original image of the photograph you just posted so I can get a perspective of the whole storm related structure. Thanks for annotating the image - well done! Now we can see more f what is going on.

Regards,

Jimmy Deguara
« Last Edit: 17 February 2010, 01:32:22 PM by Jimmy Deguara »
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Offline Richary

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I have just done some googling for possible damage reports/images/videos related to this event in northern Victoria but haven't had any luck. The local ABC reports little damage from the 11th - though of course if tornadoes did form and luckily didn't hit any houses etc that would be the case. I thought that someone who didn't really know what they were seeing might have posted a picture in any case somewhere.

Oh well, was hoping I could find some other supporting evidence, with the number of camera/video phones out there these days had hoped someone might have posted something. So regrettably the search results don't really help or hinder the discussions. I will leave it to those with more meteorological knowledge than myself to disect the pictures and evidence, and watch on with interest.

That said John and Brad - I for one appreciate the extra time you are spending in analysing damage tracks etc and comparing to radar echoes rather than the usual "here is the photo/video" - and move on.


http://www.abc.net.au/news/stories/2010/02/12/2817969.htm?site=goulburnmurray


More stormy weather forecast

Stormy weather is expected to continue in the Goulburn Murray region in coming days.

There was little damage from storms yesterday and rainfall ranging from five to 20 millimetres.

Dean Scarbossa from the weather bureau says storm conditions will ease today but he says they are likely to stay well into next week.

"For at least the next seven days it looks like it will be a similar situation," he said.
« Last Edit: 17 February 2010, 03:00:19 PM by Jimmy Deguara »

Offline nzstorm

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The thing to remember about tornadoes is that like clouds they came in lots of different forms and often they can be obscured. The photo above certainly looks like a vortex.  The Melbourne sounding shows a strong upper NW flow which I think is the primary ingredient to look for. The low level enhanced shear will not show up in any modeling. Looks like some interesting storm days for you guys.
Steven Williams
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