Another wild night in Tornado Alley

By: Dr. Jeff Masters , 11:40 AM GMT on May 06, 2007

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The sirens sounded two more times in tornado-ravaged Greensburg, Kansas last night, as two more twisters tore through the county. However, both tornadoes missed populated areas, as did most of the approximately 75 tornadoes that touched down yesterday. The action should quiet down considerably today; the Storm Prediction Center (SPC) has placed most of Kansas and Nebraska under its "Slight Risk" area for severe weather. Sweetwater, Oklahoma received significant damage from a tornado last night, and we've saved 300 Kb animations of the radar reflectivity and Doppler velocities of the tornado.

It will take a long time for Greensburg to recover from Friday's tornado. To get an idea of the scale of devastation, see the aerial photos posted by the Wichita Eagle. Damage surveys are not yet complete on the tornado, but photos I've seen of the destruction show damage consistent with EF4 winds(168-199 mph). It is possible the storm was an EF5 (winds more than 200 mph). The nine deaths from the tornado bring the U.S. tornado death toll to 68 so far this year, two more than the toll for all of last year.

We've saved some extraordinary 1 Mb animations of the radar reflectivity and Doppler velocities of the tornado. I asked wunderground meteorologist and tornado expert Rob Carver to comment on what's going on in the animations, and here was his analysis:

This was likely an example of cyclic mesocyclogenesis. In a nutshell, the rear-flank downdraft surges out, wraps around and occludes the mesocyclone (Meso A for short). Meso A then veers to the left and dies, this is why tornado family members curve to the left as they dissipate. While Meso A is dying, a new meso spins up and becomes the dominant meso. Now, while I've seen plenty of simulated cyclic cases where the hook retreats when Meso A occludes, I don't think I've seen anything as dramatic.



Figure 1. Radar image of the storm that spawned the Greensburg, KS tornado of May 4, 2007, showing the clearly defined hook echo associated with the twister.

Coastal Carolina storm
The latest (8pm EDT) computer forecast models continue to show a moderately strong coastal storm developing several hundred miles southeast of Cape Hatteras, North Carolina, on Monday. The storm will be extratropical in nature when it forms. We'll have a lot of time to watch the storm, as it is expected to meander offshore for five days and gradually weaken. Water temperatures are 22-23 C off of the coast, which may be warm enough to allow the low to acquire some subtropical characteristics and become the season's first named storm. The models are hinting that the storm could remain over water long enough for this to happen, and I put the odds of a Subtropical Storm Andrea forming late this week at about 20%.

Wunderblogger Mike Theiss was out chasing yesterday and caught some of the storms; be sure to tune into his blog over the next few days to read his chase accounts. Stormchaser Dan Robinson posted some video stills of the Greensburg tornado.

Jeff Masters

()
Storm Brewing (thomasanthony)
A big storm moved in on the 3rd. Wasn't as bad as it looked though.
Storm Brewing

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483. StormJunkie
11:09 PM GMT on May 06, 2007
Evening all ☺

Drak, I think once it gets in lower shear it will be able to create more moisture. It is just now getting near some reasonably warm SSTs in the Gulf Stream and the shear should drop off over the next 24 or so.
Member Since: August 17, 2005 Posts: 26 Comments: 16417
482. V26R
11:07 PM GMT on May 06, 2007
Hey Roman you should get your camera out and get some Pix
Member Since: July 20, 2006 Posts: 0 Comments: 1762
481. V26R
11:06 PM GMT on May 06, 2007
Just the bottm edge of a trough moving south
Would take alot of things to happen to get those Boomers to form into anything special
Member Since: July 20, 2006 Posts: 0 Comments: 1762
480. HurricaneRoman
11:05 PM GMT on May 06, 2007
I see thunder and lightning and dark skies but the storm isnt close enough yet... I think its gonna come right over me.... i'll tell u guys if anything happens
Member Since: February 25, 2006 Posts: 2 Comments: 959
479. Drakoen
11:05 PM GMT on May 06, 2007
i think that low by the Carolinas is taking in dry air but the models still say that it will develop.
Member Since: October 28, 2006 Posts: 57 Comments: 30306
478. DocBen
11:04 PM GMT on May 06, 2007
That big storm over FL - could it go off-shore and develop?
Member Since: May 16, 2006 Posts: 0 Comments: 98
477. StormJunkie
11:04 PM GMT on May 06, 2007
WV SE Low

Lot of dry air in there right now.
Member Since: August 17, 2005 Posts: 26 Comments: 16417
476. V26R
11:04 PM GMT on May 06, 2007
Just did it
Man that is a pain!
Thanks Guys
Member Since: July 20, 2006 Posts: 0 Comments: 1762
475. MissBennet
11:03 PM GMT on May 06, 2007
Posted By: Bamatracker

booooooooooo!!!! the blog is stretched!!


weathersp <--- his/her fault!

Please, please fix your pic, weathersp
474. kmanislander
11:02 PM GMT on May 06, 2007
V26R

Change the setting as suggested. Worked for me
Member Since: August 19, 2006 Posts: 0 Comments: 15813
473. kmanislander
11:02 PM GMT on May 06, 2007
Thanks Bama/STL

That fixed it. Didn't realise I had it set to show all !!
Member Since: August 19, 2006 Posts: 0 Comments: 15813
472. V26R
11:00 PM GMT on May 06, 2007
Kman I have the same on my screen too
Member Since: July 20, 2006 Posts: 0 Comments: 1762
471. Skyepony (Mod)
11:00 PM GMT on May 06, 2007
jp ~ no problem with the SSD site here.
Member Since: August 10, 2005 Posts: 162 Comments: 37822
469. Bamatracker
10:57 PM GMT on May 06, 2007
hey kman...put it on showing 50 comments it it should fix ya
Member Since: May 17, 2006 Posts: 6 Comments: 1367
468. leelee75k
10:57 PM GMT on May 06, 2007
hi all,

in sunrise, near tamarac, got dark for a few minutes, a little rain but nothing serious or intense. heavier clouds are to the west of my location heading south.
Member Since: September 9, 2005 Posts: 0 Comments: 559
467. kmanislander
10:55 PM GMT on May 06, 2007
RL340

I have to scroll left to right to read entries. Wasn't that way a while ago
Member Since: August 19, 2006 Posts: 0 Comments: 15813
465. RL3AO
10:54 PM GMT on May 06, 2007
Posted By: kmanislander at 5:51 PM CDT on May 06, 2007.
who stretched the blog ??


I dont see any pics wider that 640.
464. Skyepony (Mod)
10:53 PM GMT on May 06, 2007
STL~ The ESPI has dropped like a rock this week to -1.15 from the -.20s, lowest so far with this ENSO switch. We should be seeing ENSO cool a good bit in the next few weeks.
Member Since: August 10, 2005 Posts: 162 Comments: 37822
463. kmanislander
10:53 PM GMT on May 06, 2007
Thanks HR

I gave them a call and they are now following developments
Member Since: August 19, 2006 Posts: 0 Comments: 15813
462. Drakoen
10:52 PM GMT on May 06, 2007
I will be interested to see what the NHC says at 8:00 pm on the current situation with the system. Remember guys its not even at invest yet.
Member Since: October 28, 2006 Posts: 57 Comments: 30306
461. HurricaneRoman
10:52 PM GMT on May 06, 2007
I live like 10 miles form pembroke pines.... the storm isnt here yet but it should be getting to us soon
Member Since: February 25, 2006 Posts: 2 Comments: 959
460. kmanislander
10:51 PM GMT on May 06, 2007
who stretched the blog ??
Member Since: August 19, 2006 Posts: 0 Comments: 15813
459. Drakoen
10:51 PM GMT on May 06, 2007
I just wanna see what happens as it moves to the Southwest.
Member Since: October 28, 2006 Posts: 57 Comments: 30306
458. Skyepony (Mod)
10:50 PM GMT on May 06, 2007
NFL wasn't my guess, I was agreeing with RL... The ECMWF ~ I was just throwing not so run of the mill model runs out there as I was looking at them. That one stands alone with it's precipitation free low left on the gulf after it has it crossing FL.
Member Since: August 10, 2005 Posts: 162 Comments: 37822
456. Skyepony (Mod)
10:45 PM GMT on May 06, 2007
A nearby buoy

Wind Direction (WDIR): NNE ( 20 deg true )
Wind Speed (WSPD): 36.9 kts
Wind Gust (GST): 46.6 kts
Wave Height (WVHT): 16.1 ft
Atmospheric Pressure (PRES): 29.82 in
Member Since: August 10, 2005 Posts: 162 Comments: 37822
454. RL3AO
10:44 PM GMT on May 06, 2007
There is some mid-level rotation.

1
453. Drakoen
10:42 PM GMT on May 06, 2007
Posted By: Skyepony at 10:39 PM GMT on May 06, 2007.

RL~ That would be my guess..

ECMWF

north Florida. Now if only it would go 100 miles to the South lol.
Member Since: October 28, 2006 Posts: 57 Comments: 30306
452. kmanislander
10:41 PM GMT on May 06, 2007
Hi all

Anyone on living near Pembroke Pines ?
My wife's Mom and sister live there
Member Since: August 19, 2006 Posts: 0 Comments: 15813
451. Drakoen
10:40 PM GMT on May 06, 2007
Posted By: Skyepony at 10:36 PM GMT on May 06, 2007.

canadian gem model


interesting has it stregthing with pressure typically seen in a Cat 1 hurricane
Member Since: October 28, 2006 Posts: 57 Comments: 30306
450. HurricaneRoman
10:39 PM GMT on May 06, 2007
their is a wall cloud with the severe storm in central broward...... dark clouds are starting to come here
Member Since: February 25, 2006 Posts: 2 Comments: 959
449. Skyepony (Mod)
10:38 PM GMT on May 06, 2007
RL~ That would be my guess..

ECMWF
Member Since: August 10, 2005 Posts: 162 Comments: 37822
448. HurricaneKing
6:39 PM EDT on May 06, 2007
Yes That looks about right for where the center is.
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447. Drakoen
10:38 PM GMT on May 06, 2007
Posted By: RL3AO at 10:38 PM GMT on May 06, 2007.

Did I get the location right?

yes. broad low pressure
Member Since: October 28, 2006 Posts: 57 Comments: 30306
446. RL3AO
5:34 PM CDT on May 06, 2007
Did I get the location right?

1
445. Skyepony (Mod)
10:32 PM GMT on May 06, 2007
canadian gem model
Member Since: August 10, 2005 Posts: 162 Comments: 37822
444. Skyepony (Mod)
10:14 PM GMT on May 06, 2007
This evening's quikscat pass was a total miss.

I thought it was looking slightly more organized by the RGB loop.
Member Since: August 10, 2005 Posts: 162 Comments: 37822
443. V26R
10:28 PM GMT on May 06, 2007
Lilmax try
Link

Click on the free map its refreshed quickly
Mike
Member Since: July 20, 2006 Posts: 0 Comments: 1762
442. HurricaneRoman
10:21 PM GMT on May 06, 2007
is it possible for it to start again??
Member Since: February 25, 2006 Posts: 2 Comments: 959
440. Drakoen
10:20 PM GMT on May 06, 2007
Posted By: RL3AO at 10:19 PM GMT on May 06, 2007.

The low level rotation has stopped for the moment in Broward


thats good to hear
Member Since: October 28, 2006 Posts: 57 Comments: 30306
439. RL3AO
5:17 PM CDT on May 06, 2007
The low level rotation has stopped for the moment in Broward.
438. lilmax
10:16 PM GMT on May 06, 2007
Anyone has a good website for high quality free lightning tracking?
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437. HurricaneRoman
10:16 PM GMT on May 06, 2007
I live in Miramar in Broward
Member Since: February 25, 2006 Posts: 2 Comments: 959
436. hurricane23
18:15 EDT le 06 mai 2007
TORNADO WARNING CONTINUES!

GG
Member Since: Posts: Comments:
435. Drakoen
10:13 PM GMT on May 06, 2007
Posted By: Bamatracker at 10:11 PM GMT on May 06, 2007.

Link

This is the quickest updated model page i know of.


thanks interesting, even though the system dissaptes the low still mvoes into Florida. I wanna see what the other models have to say.
Member Since: October 28, 2006 Posts: 57 Comments: 30306
434. RL3AO
5:12 PM CDT on May 06, 2007
Roman, where do you live in Broward County?

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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