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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783. RL3AO
9:24 PM CDT on May 06, 2007
Posted By: KoritheMan at 9:20 PM CDT on May 06, 2007.

Also cyclone, WHAT THE HECK is a tunnel? o_O


Here we go.
782. CryptKicker
2:24 AM GMT on May 07, 2007
Doc, last night's tornado was in Sweetwater, OK, not Sweetwater, TX.
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781. weatherboykris
2:22 AM GMT on May 07, 2007
Just don't ask...LOL.BBL
Member Since: December 9, 2006 Posts: 125 Comments: 11346
780. KoritheMan
2:18 AM GMT on May 07, 2007
cyclonebuster, tornadoes will always occur. No one can stop them. I love life too, but nothing I or anyone else can do about disasters. Keep up the preparation for them, since they WILL continue to happen. I hate complacency more than anything (not offending you or anything).

Also cyclone, WHAT THE HECK is a tunnel? o_O
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778. hurricane23
10:15 PM EDT on May 06, 2007
This lows chance at becoming hybrid or tropical will be within 24-36 hours.
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777. Ldog74
2:13 AM GMT on May 07, 2007
Hows everyone doin tonite. Usual suspects are here, and the heated debates continue. I see we have a potential system to keep an eye on over the next couple of days. I'd give it 25-30%, but count your blessings, if this storm were taking place in '05, it'd probably be a full-fledged hurricane by now.
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776. WKendallGuy
9:11 PM EST on May 06, 2007
The tornado will be near...
intersection krome and Kendall drive by 845 PM EDT...
Kendall Lakes by 850 PM EDT...
The Hammocks and West Kendall by 855 PM EDT...

I'm in the Hammocks and didn't notice any tornado, the dogs were barking fiercely though. Missed another bullet.

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775. stormhank
2:10 AM GMT on May 07, 2007
Wouldnt u all agree though that the GFDL is probably one of the best models?I remember back in 2005 it forecast the SW motion of Katrina over south Fla a day or so before it really happened?
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774. pottery
10:11 PM AST on May 06, 2007
.Thanks again.
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773. StormJunkie
2:08 AM GMT on May 07, 2007
Evening all. It is E of Hatteras pottery. Good to see you.

You can find the National Bouy Data center from the marine section here.

All right y'all I am off to bed. Got to work early. Will be intersting to see if it can build some moisture on that western side.
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771. Patrap
9:09 PM CDT on May 06, 2007
The buoy 5 day plot..graphically..Link
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770. pottery
10:09 PM AST on May 06, 2007
Thanks
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768. Patrap
9:07 PM CDT on May 06, 2007
NDBC Hatteras Buoy Link
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767. FTmyersZ
10:07 PM EDT on May 06, 2007
Station 41001 - 150 NM East of Cape HATTERAS
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765. pottery
10:05 PM AST on May 06, 2007
Where is bouy ..001 ??
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764. weatherboykris
2:05 AM GMT on May 07, 2007
I don't think so...after all,it is May.We aren't THAT far from the start of the season.
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763. lilmax
2:05 AM GMT on May 07, 2007
40% Chance.
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762. hurricaneman23
2:04 AM GMT on May 07, 2007
45%? thats pretty high
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758. weatherboykris
2:02 AM GMT on May 07, 2007
I'll go with 45%.
Member Since: December 9, 2006 Posts: 125 Comments: 11346
757. KoritheMan
2:01 AM GMT on May 07, 2007
Who here thinks Andrea will develop? I give it a 35% chance of occuring.
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756. kmanislander
1:59 AM GMT on May 07, 2007
Stormhank

They will crank up the gfdl when an invest is declared
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755. lilmax
1:57 AM GMT on May 07, 2007
You have a point there Jackp0t, but it is about to become a warm-core storm, nor'easters aren't warm-core.
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754. weatherboykris
2:00 AM GMT on May 07, 2007
The GFDL only runs on invests.
Member Since: December 9, 2006 Posts: 125 Comments: 11346
753. stormhank
1:58 AM GMT on May 07, 2007
Hey Kris n Adrian!!! I wonder when or if the GFDL model will start up? It doesnt go year round like the CMC n GFS does it??
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752. KoritheMan
1:58 AM GMT on May 07, 2007
Yeah kris, I agree. Shear will improve, and Andrea might form. The most it'll get I think is 60 mph as a tropical storm, and 45 mph as a subtropical storm.
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751. lilmax
1:49 AM GMT on May 07, 2007
Another batch of thunderstorms moving in from the north-northeast. Thankfully it doesn't look so concentrated as the first batch.
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750. weatherboykris
1:55 AM GMT on May 07, 2007
Thanks Adrian,but I have to disagree with them.Shear will get better the next few days.
Member Since: December 9, 2006 Posts: 125 Comments: 11346
749. Jackp0t789
1:52 AM GMT on May 07, 2007
With the comma shape, it looks more like a Noreaster...
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748. hurricaneman23
1:53 AM GMT on May 07, 2007
yea 2 different people
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747. hurricane23
9:52 PM EDT on May 06, 2007
Kris this is from IWIC...

After observing the models the last couple days, it looks as if the western Atlantic low will initially strengthen via baroclinic forcing. Over time, the low will begin to acquire subtropical or tropical characteristics. However, upper level conditions cannot sustain a tropical (warm core) low at this time. So the more tropical it becomes, the more it will weaken. The models also show the low drifting west into the southeast USA underneath a high to the north. It would be nice if the southeast could get some rain (drought), but the low will likely be too weak to bring any torrential rainfall by the time it moves inland. All that being said, the low should be monitored for hybrid development over the next few days.
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746. ecflawthr
1:52 AM GMT on May 07, 2007
any large hail in fl today?
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745. kmanislander
1:53 AM GMT on May 07, 2007
will the real slim shady please stand up LOL
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744. kmanislander
1:52 AM GMT on May 07, 2007
apparently
Odd though. I guess someone likes your handle LOL
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743. pottery
9:41 PM AST on May 06, 2007
The ITCZ , from Venezuela, through to Panama and into the Pacific, is begining to produce some real weather, at last........
Member Since: October 24, 2005 Posts: 0 Comments: 24060
742. weatherboykris
1:48 AM GMT on May 07, 2007
I'd like to know where you think you got the right to toss around the stupid idea that the TUNNELS could stop tornadoes....two days after a town was wiped off the map,and when several people have died in the past few days.Why don't you show a little consideration,and show some sympathy for those poor people,instead of using them as examples like a fear monger."You'd better support my TUNNELS,or this could happen to you!"
Member Since: December 9, 2006 Posts: 125 Comments: 11346
741. hurricane23
9:51 PM EDT on May 06, 2007
2 different people kman.
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740. BahaHurican
9:40 PM EDT on May 06, 2007
don't know why anybody would ever want to have to load all of the comments in a blog, especially when there are hundreds and tons of pictures - a horror even with high speed Internet).

Actually, I usually load them all, unless I've read most of them already. It's too much of a hassle to keep pressing NEXT when I can just scroll down as I read.

Just about the only time I use the 50 comments setting is when the blog is well over 1000 comments and I have already read more than 85% of them.

The picture that's stretching the blog, btw, is the one showing the Greenburg F-5 tornado. Perhaps the person who posted it could go back and edit the size?
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739. kmanislander
1:49 AM GMT on May 07, 2007
hurricane 23 ?
hurricaneman 23??

HUH ?
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737. RL3AO
8:44 PM CDT on May 06, 2007
thats starting to look a little more sub-tropical, but its not there yet.
736. kmanislander
1:46 AM GMT on May 07, 2007
23

Max retired last year. Proenza is the new director

Link
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735. hurricane23
21:46 EDT le 06 mai 2007
48hr forcast...

g
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734. weathermanwannabe
9:43 PM EDT on May 06, 2007
The Florida rain event missed me here (sadly) in the Big Bend but gave the East Coast and Central/South Florida a good shot....Enjoy it until the next one and Good Night all...
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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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