Topic: Greensburg tornadic supercell

[Michael Thomas]

I came across an interesting paper on the Greensburg storm. I suggest having a read if you have the time. The authors report the presence of a 'vortex hole' from radar observations. That is a cone of weaker reflectivities penetrating downwards into the storms core. Just when you thought you had an understanding of supercell structure, think again. Amazing example of what can happen with high CAPE and strong low level shear.

Michael

Edit: Forgot the link - http://ams.confex.com/ams/24SLS/techprogram/paper_141811.htm

[Brad Hannon]

Michael, thankyou so much for that link.  What a fantastic presentation and some amazing conclusions they are beginning to draw from that event.  And to think that Jimmy and I (and Macca and Chris as well) were very close to that storm and could well have been in its path if we'd made a few different decisions earlier in the evening    Thanks again.

[Mike]

Earlier this year Greensburg narrowly missed being hit once again.  I've included this 8 minute video from Reed Timmer's chase crew who filmed this incredible tornado during their Discovery Channel series currently airing in the US with Dr Josh Wurman with his DOW and Sean with his new IMAX TIV.  Those members who have visited the US will find this tantalizing! 

It features the insane tornado outbreak of May 23, 2008, when 64 tornadoes were reported across the Southern Plains.  On this day, several tornadoes touched down in and around Quinter, KS, including an EF4 that crossed I-70 just to the west of town; an EF3 tornado struck a farmhouse near Ft. Supply, OK; and Greensburg, KS was nearly hit again by a strong tornado.

http://www.youtube.com/v/XM-0yYfmdv0&color1=0xb1b1b1&color2=0xcfcfcf&hl=en&feature=player_embedded&fs=1

[Brad Hannon]

Just to clarify re that Youtube video - that is one of the Quinter tornadoes from the 23rd May this year and not one of several that threatened and even caused some damage in Greensburg again.

Macca and I were further south at the time and although we sadly missed that one and also the wedge that came through that area we did still manage to see a lazy half dozen or so tornadoes that day and a similar number the next day!   Included in these were a ripper multivortex, several tall elephant trunk tornadoes and at one stage at least 2 on the ground at once, followed very quickly by a third which may well have been on the ground at the same time.

Regarding Greensburg, I actually lost count of how many times Greensburg was again under the gun this year with tornado warned storms and confirmed tornadoes tracking towards the town predominantly from the SW.  Using the Mobile Threatnet software while we were chasing, we could see these tornado warned cells as they tracked towards Greensburg and there was a feeling of 'surely theyre not going to be hit again!' - one circulation in particular I recall passed directly over the town but we found out later there was no tornado at the time.  On another occasion, they definately suffered some (minor?) damage from a tornado on the outskirts of town and the townspeople went to underground shelter at least once during May with tornado sirens blaring.  In fact, on one of our last chase days, Macca and I actually chased a rapidly rotating tornado warned storm from the south on the infamous US183 toward and then through the abandoned and flooded streets of Greensburg and then toward Pratt to the East (where it later produced several weak tornadoes).  It was an eerie experience. We then got pounded by baseball size hail to the east of Greensburg - there were reports of larger hail to the west of us   We spent a lot of time chasing in that region of Kansas this year and constantly came across very wide damage paths (mainly evidenced by large expanses of stripped and damaged trees) caused by the super wedges and the smaller tornadoes of May 4th 2007.

[Mike]

Hi there,  video was not intended to portray the pending Greensburg events this year so I jut wanted to confirm that also - purely for viewing pruposes.

[Mike]

Full NWS report on the Greensburg by Lemon & Umscheid - this is something I'll be keeping. Those members who were there will find this fascinating. http://ams.confex.com/ams/pdfpapers/141811.pdf

[Jimmy Deguara]

Hi Mike,

I skimmed over the report late last night and it was readble - not too technical. Certainly significant rotation indicated and interesting that we are now looking at a resolution whereby there is uncertainty whether doppler is indictating rotation of a major tornado or subvorticies. It seems that at least in part, a major tornado is beign indictaed - obviously subvorticies are to be anticipated. Well worth the read. I also like the fact that the explosive term is used because that is what happened on this day. Another feature that seems to be indictaed is something I have read before in the Kansas tornado outbreak in June 15th 1992 where supercells were rotating around each other and prolific tornado producers.

Certainly an incredible event.

Regards,

Jimmy Deguara

[Mike]

Quite amazing that Doppler did not pick it up prior to it forming or indicated the presence of such a large meso - but as reported 'explosive' means just that - it really must have literally gone atomic in structure - it is mind boggling to think that even when we thought we knew most things about supercells, along comes an event - possibly once how many years - that these supercells really were a wonder of nature and scientifically, rewrites records books in some way.

[Macca]

Really interesting article. 

Mike - I'm pretty sure the doppler was all over this storm (hence why the NWS issued the tornado warning for Greensburg (and surrounds) nearly 30 minutes prior to them being hit. 

I find it very interesting too Jimmy - the article suggests that either the doppler detected tornado was a massive 4+km in diameter at its widest point (as is indicated by the wind speeds estimated by the doppler and supported by the damage path assessment done) OR the whole meso was on the ground with tornadic vorticies rotating within this meso (which visually would be impossible to see if the whole meso was condensed to the ground - and thus at what point do you call this a tornado?  you would think when the wind speeds exceed the threshhold for tornadoes...which it did...so based on this, the whole thing is just a massive tornado, right?). 

Certainly an interesting article and it was interesting to be part of that day.

Macca

[Mike]

Macca, yes just a bad choice of words whilst typing on the fly sorry!

[Brad Hannon]

I also found the research paper from Mike Umsheid and Leslie Lemon to be an incredible read about a phenomenal event.  It's great to see scientific analysis using radar, 3D imagery, photographs and personal obs and accounts being used to form some understanding of what took place that evening and night.  It is such a shame that it occured at and after dark because it would've been a phenomenal sight in daylight and wouldve provided more visual clues to the storms behaviour.  It gives me renewed enthusiasm to get my footage out and review it frame by frame - something I've been meaning to do for a long time heh Jimmy

On a slightly different note (but still about Greensburg):

When Macca and I were in Greensburg this year we had the pleasure of spending the best part of a day with a couple, Scott and Susan who survived the Greensburg tornado in their basement.  We were introduced to them by Marko Korosec who was chasing with us this year.  Their house was destroyed by the tornado but they have started a new business and were preparing to rebuild on the site of their old house.  Their stories of the tornado, survival, the aftermath and rebuilding were amazing.  Despite their resillience and positive attitude you could sense that they were still fragile after having lost everything and they admitted that they found it very hard to watch footage or see photos of the tornado even 12 months later.  I have kept in contact with them a little by email and after emailing back and forward with them today about christmas and my son, I wondered whether it would be beneficial or painful for them to read the research paper about what happened that night. After giving it due consideration, I decided to send them the link and let them decide - Im glad I did as Scott soon replied with a statement that I think is very relevant to this thread and the research findings of Umscheid and Lemon.

From Scott Reinecke of Greensburg, Kansas:

Thanks for the article.  Although I don't understand a good deal of the scientific terminology, it was still a fascinating read.  I might point out that, like Megan and Chris Gardeners' observations, I can confirm that the intense pressure change and accompanying pain did precede the tornadic destructive winds.  Also, after the tornado passed over, a few minutes of calm passed, then came another intense pressure change that was again followed by what we thought at the time was a second tornado.  We were later told that what we experienced the second time was the inflow of what became the Trousdale tornado.  But each pressure change came BEFORE the destructive winds.

Just so you know, Scott and Susan were trapped for some time before they were able to climb out of the rubble and Im fairly sure they had one of their mothers with them also.

Macca, Im not sure if you've been in contact with Scott and Susan but you may have something to add?

[Mike]

Hi Brad, very moving to read their comment considering what they went through. I'm pleased that you met these fine people and trying to understand what they went through is just not possible from my perspective at least.  Glad the link was informative for them.