Another wild night in Tornado Alley

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

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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232. RL3AO
2:06 PM CDT on May 06, 2007
The first EF-5. I wonder what it would have recieved on the Fujita scale. In theory, it would have been an F5.
231. Chicklit
7:04 PM GMT on May 06, 2007
Oh yeah...There's a whole mess just north of us. I just don't believe it will get here. It's been that kind of a spring.
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229. Chicklit
7:02 PM GMT on May 06, 2007
C'mon and bring it on! We need the rain.
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228. HurricaneKing
3:03 PM EDT on May 06, 2007
Here's a loop closer to the center.
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225. HurricaneRoman
7:00 PM GMT on May 06, 2007
Hey ... if u guys didnt know ...the tornado that hit greensburg was an EF5 , the first of the season!
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224. Chicklit
6:58 PM GMT on May 06, 2007
Here just south of Daytona I hear thunder, smell smoke; where's the rain?
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6:52 PM GMT on May 06, 2007
Hey it is finally raining in Punta Gorda Florida been a long time here !!!!
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221. Drakoen
6:51 PM GMT on May 06, 2007
ok the big circle i'm guess is the future system. Is the there a spin in the inner circle?
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216. Chicklit
6:38 PM GMT on May 06, 2007
Hey boys and's finally raining in east Central Florida! Thanks For that since it's the driest it's been in 25 years...My dog is not happy, though, since we were supposed to go to the Inlet this afternoon for a swim...Anybody have any idea what's going to happen with this system
in New Smyrna Beach?
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213. HurricaneKing
2:36 PM EDT on May 06, 2007
Here is my personal opinion on the storm. I think it will become subtropical. I think it will move very close to Florida and then loop north toward the NC/Sc border. After that it could do three things. 1. Die out. 2. Make landfall. 3. Spin out to sea. As of right now I'm leaning toward 2.
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212. Dyce
2:35 PM EDT on May 06, 2007
hearing thunder here in orlando
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211. hurricanealley
6:34 PM GMT on May 06, 2007
good afternoon everyone
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6:28 PM GMT on May 06, 2007
Storms with Hail

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208. Drakoen
6:31 PM GMT on May 06, 2007
the system is getting pushed further south. Maybe the moedls do not have an idea of where the center of the storm is yet.
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206. Thundercloud01221991
6:30 PM GMT on May 06, 2007
If it goes into Florida what are the chances of it moving out the other side into the Gulf
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205. melwerle
6:30 PM GMT on May 06, 2007
ok - i gotta take a break from this for a bit. I'll catch up later and see what is going on. Y'all have a great afternoon. My couch is calling me!
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204. weatherboykris
6:29 PM GMT on May 06, 2007
Member Since: December 9, 2006 Posts: 125 Comments: 11346
203. weatherboykris
6:28 PM GMT on May 06, 2007
I do belive you are right HK.
Member Since: December 9, 2006 Posts: 125 Comments: 11346
202. cajunkid
6:24 PM GMT on May 06, 2007
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200. HurricaneKing
2:27 PM EDT on May 06, 2007
From what I can tell the actual center is in the blob off of the NC/VA border.
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198. RL3AO
1:25 PM CDT on May 06, 2007
You can really see the low starting to develop on that IR.
195. melwerle
6:26 PM GMT on May 06, 2007
Hey Storm - you have mail.
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194. weatherboykris
6:24 PM GMT on May 06, 2007
Don't bother StormW,just looked at a loop myself.Yeah,I see what you're saying.The storm will form farther south than most models have it.
Member Since: December 9, 2006 Posts: 125 Comments: 11346
192. cajunkid
6:22 PM GMT on May 06, 2007
south east coast WV
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190. weatherboykris
6:18 PM GMT on May 06, 2007
StormW.I know the turn could be not as sharp.Several models are saying just that.I'm reluctant to forecast a TS landfall on the east coast of FL in May,LOL.
Member Since: December 9, 2006 Posts: 125 Comments: 11346
189. cajunkid
6:19 PM GMT on May 06, 2007
south east coast IR
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188. weathersp
2:14 PM EDT on May 06, 2007
LA Boy from what we have now its hard to predict the track of this thing after 48hrs or so. Will it go north? Will it keep going south? Or will it just turn back out to sea... we just don't know yet until it forms tonight/tomorrow Morning
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187. chessrascal
6:14 PM GMT on May 06, 2007
the only thing we can be pretty sure about is that it is going to head toward Florida but until it gets closer we cant be sure about much.

Anyone agree?
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186. pottery
2:13 PM AST on May 06, 2007
444. Thats a prediction, not a truth as yet.
Although the person who made the predict. could very well be correct.
But then, so could everyone else.
Its great, isnt it ?
Member Since: October 24, 2005 Posts: 0 Comments: 27091
185. RL3AO
1:15 PM CDT on May 06, 2007
look at some of these rain totals


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