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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583. weatherguy03
7:47 PM EDT on May 06, 2007
And then there is GetReal and the conspiracy theory!!..LOL
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582. Drakoen
11:46 PM GMT on May 06, 2007
Posted By: weatherguy03 at 11:46 PM GMT on May 06, 2007.

Drakoen. I believe we will get an Invest. I have said that all along. We can still get an Invest and have a Subtropical storm
.

I am waiting for that 8:00 pm adversory then i will base everything on that. I would prefer to listen to professionals knowledge. And i doubt it will be a cold core system considering the Golf Stream.
Member Since: October 28, 2006 Posts: 57 Comments: 30495
581. Bamatracker
11:46 PM GMT on May 06, 2007
new discussion from NHC

WESTERN ATLANTIC...
THE BIG STORY IS ASSOCIATED WITH A STRENGTHENING LOW PRES SYSTEM
OFF THE CAROLINA COASTLINE....ANALYZED 1009 MB NEAR 35N74W. A
BACK DOOR COLD FRONT IS PROGRESSING SWD FROM THE LOW TO NE
FLORIDA. THIS LOW HAS AN IMPRESSIVE LARGE CIRCULATION WITH
MULTIPLE BOUNDARIES ROTATING AROUND IT PRODUCING SCATTERED
SHOWERS N OF 28N W OF 70W. THE MAIN IMPACT IS THE STRONG WINDS
AS A VERY TIGHT PRES GRADIENT HAS SET UP BETWEEN THE LOW AND
STRONG HIGH PRES OVER THE ERN GREAT LAKES. SHIPS/BUOYS ARE
REPORTING NLY WINDS TO 40 KT NOT FAR OFF THE SE COAST. GLOBAL
MODELS ARE NOW IN PRETTY GOOD AGREEMENT SHOWING THE SYSTEM
STRENGTHENING FURTHER AS IT TAKES A LOOPING OR SLOW WWD MOTION
TOWARD THE SE COAST. SEVERAL MODELS ARE ALSO SHOWING THE SYSTEM
BECOMING LESS FRONTAL IN NATURE OVER THE NEXT COUPLE DAYS.
MARINE IMPACTS ARE EXPECTED TO BE SIGNIFICANT IN THE NW PORTION
OF THE AREA...REFER TO MIAHSFAT2 FOR DETAILS S OF 31N. FARTHER
E...A WEAK 1011 MB LOW LOCATED NEAR 28N61W IS PRODUCING
SCATTERED SHOWER ACTIVITY NE OF THE LOW FROM 26N-31N BETWEEN
55W-57W. A SFC TROUGH HANGS S/SW FROM THE LOW TOWARD THE NRN
COAST OF HISPANIOLA...DEFINED BY A WIND SHIFT.
Member Since: May 17, 2006 Posts: 6 Comments: 1367
580. weatherguy03
7:46 PM EDT on May 06, 2007
JP. I think we may see a Subtropical storm, but not a tropical system. So something is gonna form. Nah, I am wrong sometimes..LOL
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578. RL3AO
6:45 PM CDT on May 06, 2007
I didnt catch TWC report, but did they mention the "T" word? (Tropical)
577. Drakoen
11:45 PM GMT on May 06, 2007
Posted By: MTJax at 11:45 PM GMT on May 06, 2007.

oh look... its up on the Navy site!! JK

oh crap lol Link me please
Member Since: October 28, 2006 Posts: 57 Comments: 30495
576. Patrap
6:43 PM CDT on May 06, 2007
GOM SSTs 60 hour model run. Link
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575. weatherguy03
7:45 PM EDT on May 06, 2007
Drakoen. I believe we will get an Invest. I have said that all along. We can still get an Invest and have a Subtropical storm.
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574. GetReal
11:35 PM GMT on May 06, 2007
When, and if this low pressure area develops, and moves SW, the NHC will jump through hoops to look for reasons not to name this system. It may begin to clearly look like a sub-tropical, or tropical system, but due to politcal and economic (oil future prices) reasons the NHC will avoid naming this system...

Naming this system this early will be clearly taken as evidence that we will have an active, and above average season... Oil future prices will soar, and will hurt the overall U.S. economy (politics).
Member Since: July 4, 2005 Posts: 204 Comments: 8874
573. Bamatracker
11:43 PM GMT on May 06, 2007
lets be real here...This is a mind blowing developing situation that nobody realistically expected. Regardless wether it develops into a named storm or not this is interesting to have this promising of a potential system this early.
Member Since: May 17, 2006 Posts: 6 Comments: 1367
571. MTJax
11:44 PM GMT on May 06, 2007
oh look... its up on the Navy site!! JK
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570. melwerle
11:43 PM GMT on May 06, 2007
Saying his name sends shivers down my back..he used to make me so MAD last year. ok...another rum and coke and i should be calm...whew...had a moment. Sorry y'all.
Member Since: June 28, 2006 Posts: 12 Comments: 1837
568. HurricaneFCast
11:43 PM GMT on May 06, 2007
...Note...
Member Since: April 20, 2007 Posts: 7 Comments: 1482
567. Bamatracker
11:42 PM GMT on May 06, 2007
Its cool JAX....dont let it happen again LOL!!
Member Since: May 17, 2006 Posts: 6 Comments: 1367
566. V26R
11:42 PM GMT on May 06, 2007
Damn and Im going to miss it
Back to my real job, Fun time is over for me
Have a Nice & Safe Night Everyone
Seeya Tomorrow
TTFN
Mike
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564. Drakoen
11:41 PM GMT on May 06, 2007
Posted By: weatherguy03 at 11:38 PM GMT on May 06, 2007.

Sorry Drakoen, I will have to disagree with you. The chances of this becoming fully tropical are rather low. I would put it at about 5%.

lol i would have to disagree with that if the weather channel is talking about it being an invest i am sure that probability is much higher in the cyclogenesis
Member Since: October 28, 2006 Posts: 57 Comments: 30495
563. StormJunkie
11:39 PM GMT on May 06, 2007
Evening '03, sure wish we could have some real readings from the Gulf Stream...lol

Looking at the maps in my blog, it looks like the Gulf Stream is around 26c all the way up to the OBX. Also looks like the surounding waters are warmer then they have been the past couple of years at this time.
Member Since: August 17, 2005 Posts: 26 Comments: 16607
562. weatherguy03
7:42 PM EDT on May 06, 2007
#1. Get Firefox and you will never have a stretched blog again:)
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561. Bamatracker
11:42 PM GMT on May 06, 2007
calm down mel...dont need any ST impersonators on here...he is enough on his own
Member Since: May 17, 2006 Posts: 6 Comments: 1367
559. MTJax
11:41 PM GMT on May 06, 2007
I stretched and now fixed it. my bad
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557. weatherguy03
7:40 PM EDT on May 06, 2007
Mid to Upper 70's. Thats all. Michael. I will give you Vince and Gordon. The others were reaches!..LOL So, thats maybe less then a 5% chance..LOL
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556. hurricaneman23
11:29 PM GMT on May 06, 2007
jp for president
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555. Bamatracker
11:40 PM GMT on May 06, 2007
v26R....we are getting close to panic mode!!! Just have to wait for everyone to get here!!

also look for the rush to the local hardware stores!!
Member Since: May 17, 2006 Posts: 6 Comments: 1367
554. melwerle
11:41 PM GMT on May 06, 2007
It's a CAT 5 and it's hitting NO at 5pm on Friday. It is WRITTEN IN STONE.
Member Since: June 28, 2006 Posts: 12 Comments: 1837
553. Drakoen
11:37 PM GMT on May 06, 2007
so we are talking about number 1 or number 2 developing cause you guys got me confused.

link
Member Since: October 28, 2006 Posts: 57 Comments: 30495
552. HurricaneFCast
11:40 PM GMT on May 06, 2007
Thankyou for the additional content that supports my theory Micheal.
Member Since: April 20, 2007 Posts: 7 Comments: 1482
551. V26R
11:39 PM GMT on May 06, 2007
Okay Who Stretched the Blog?
Fess up
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550. MTJax
11:39 PM GMT on May 06, 2007
If ST was here he would set us ALL straight.
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548. HurricaneFCast
11:39 PM GMT on May 06, 2007
Weatherguy-- Sorry, you're wrong. 26.6 Degrees celsius = 79.8 F
Member Since: April 20, 2007 Posts: 7 Comments: 1482
547. melwerle
11:38 PM GMT on May 06, 2007
oh tell me the weather channel is now getting involved...

Hey - Jim Cantore can stay at my house if he wants...
Member Since: June 28, 2006 Posts: 12 Comments: 1837
545. HurricaneFCast
11:38 PM GMT on May 06, 2007
....
Member Since: April 20, 2007 Posts: 7 Comments: 1482
544. V26R
11:38 PM GMT on May 06, 2007
AHHH TUNNELS!!!!

NOOOOOO
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543. centrfla
11:37 PM GMT on May 06, 2007
i have been watching for a few months...you guys are so informative...also, thanks for showing how to shorten the page...
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542. weatherguy03
7:38 PM EDT on May 06, 2007
HFcast. They are in the Mid to Upper 70's. Marginal. And that is right near the Gulf Stream.
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541. Bamatracker
11:38 PM GMT on May 06, 2007
oohhh.....booooooooo!!! Blog stretched again!!! Booooooooo!!! Fix it Fix it now!!
Member Since: May 17, 2006 Posts: 6 Comments: 1367
540. RL3AO
6:36 PM CDT on May 06, 2007
You know if we built tunnels, we would have these cat 4 storms forming off of Florida in May. :)
539. Bamatracker
11:36 PM GMT on May 06, 2007
Im just joking around JP...I just know that its going to be fun in here since the "Hurricane Experts" on TWC have been engaged!
Member Since: May 17, 2006 Posts: 6 Comments: 1367
538. weatherguy03
7:36 PM EDT on May 06, 2007
Sorry Drakoen, I will have to disagree with you. The chances of this becoming fully tropical are rather low. I would put it at about 5%.
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537. MTJax
11:36 PM GMT on May 06, 2007
Here is the 1008. This seems to be the best view for it:

4 DAY SFC
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536. StormJunkie
11:34 PM GMT on May 06, 2007
jp, This is just a geuss here, but the heat depth at the end of a season should be a lot higher then it is at the beginning of a season. I think the point is that, for these SSTs to get something to TD or TS strength, it would be very rare.
Member Since: August 17, 2005 Posts: 26 Comments: 16607
535. melwerle
11:36 PM GMT on May 06, 2007
hey - where the heck is 27windows? I haven't seen her at all yet!
Member Since: June 28, 2006 Posts: 12 Comments: 1837
534. HurricaneFCast
11:32 PM GMT on May 06, 2007
Actually, the SST's around the East Coast of Florida are around 80 degrees according to NOAA.
Member Since: April 20, 2007 Posts: 7 Comments: 1482

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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.