Dr. Jeff Masters' WunderBlog

Greensburg tornado an EF-5; coastal storm will bring 3-5' storm surge to Carolinas
Posted by: Dr. Jeff Masters, 2:42 PM GMT en Mayo 07, 2007 +4
The huge, 1.4 mile-wide tornado that devastated Greensburg, KS on Friday night, May 4, was an EF-5 tornado on the Enhanced Fujita Scale. A preliminary damage survey by the National Weather Service found that the storm likely had 205 mph winds, putting it just above the 200 mph wind threshold for an EF5 rating. This is the first tornado ever rated as an EF5 using the new scale, adopted in February of 2007, and the first tornado to receive a "5" rating since the May 3, 1999 Moore-Bridge Creek tornado that devastated the southern suburbs of Oklahoma City. Had the Greensburg tornado hit downtown Chicago, the death toll could have easily been in the thousands, as I discussed last month in my blog, "Big Wind in the Windy City".

The severe storm action finally quieted down yesterday in Kansas and the Plains; only 11 reports of tornadoes were received, compared to 93 on Saturday and 33 on Friday. The severe weather action should stay at a slow simmer through Wednesday over the Plains; the Storm Prediction Center (SPC) has portions of the region under its "Slight Risk" area for severe weather through Wednesday. Flooding is a major concern now; most of eastern Kansas, plus large portions of Oklahoma, Texas, Missouri, Iowa, Nebraska, and South Dakota are under flood warnings. More heavy thunderstorm rains during the week are expected to add to the problem.

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.


Wunderblogger Mike Theiss was out chasing the weekend storms; be sure to tune into his blog over the next few days to read his chase accounts.


Figure 1. Visible satellite image of the May 7, 2007 coastal storm.

Coastal Carolina storm
A powerful non-tropical low pressure system formed off the coast of North Carolina last night, and is bringing tropical storm-force winds as high as 55 mph to the waters offshore the Carolina coast, according to the latest QuikSCAT satellite wind estimates. The North Carolina Diamond Shoals buoy had 17 foot seas and sustained winds of 43 mph at 9am EDT this morning, and buoy 41001 about 175 miles east of Cape Hatteras recorded sustained winds of 62 mph gusting to 80 mph at 1am this morning. Seas were 41 feet at this buoy this morning! The strong winds will bring 10-20 foot seas and significant beach erosion to the shores of North Carolina, South Carolina, and northeast Florida through Wednesday. A 3-5 foot storm surge is expected along portions of the North Carolina coast through Tuesday morning. The latest set of computer model runs have the storm drifting slowly southwest, and bring it ashore between the South Carolina and northern Florida coast on Wednesday. The storm will start to develop thunderstorm activity and a warm core, but will probably not have time to become fully subtropical and become Subtropical Storm Andrea. However, the storm is only expected to weaken slowly, and will have an impact similar to a tropical storm in regards to offshore winds and coastal flooding today and Tuesday. If the storm does indeed make landfall on Wednesday as expected, it will most likely be of tropical depression strength, with top sustained winds around 30-35 mph. Heavy rains of 1-3 inches can be expected to the north of where the center makes landfall, but rains will not be as significant as what a tropical storm would bring.

I'll have an update on this storm Tuesday morning.
Jeff Masters
Raging Waters - Mill Creek1 (Cptkirk)
Same location - evenig shots!
Raging Waters - Mill Creek1
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Storm Cloud Formation (FT2)
Detail of Turbulance Under the Trough on 05/06/2007 in SE Iowa.
Storm Cloud Formation
Categories: Tornado
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351. StoryOfTheCane 8:58 PM GMT en Mayo 07, 2007    
actually nevermind, I just looked at it and it is no longer in the forecast, there was something huge there last night
352. melwerle 8:59 PM GMT en Mayo 07, 2007    
COCKTAIL TIME. Cocktails and storm watching. It doesn't get any nice than this.
Member Since: Junio 28, 2006 Posts: 12 Comments: 1837
353. StoryOfTheCane 9:04 PM GMT en Mayo 07, 2007    
The GFS shows the possible first Pacific storm on the 17th
355. StoryOfTheCane 9:05 PM GMT en Mayo 07, 2007    
lol very true JFLORIDA
356. StoryOfTheCane 9:06 PM GMT en Mayo 07, 2007    
lol "MySpace Happy Weather Utopias" thats funny stuff right there
358. StormJunkie 9:07 PM GMT en Mayo 07, 2007    
Well, still not much convection, but the dry air does not look like it is making it in to the center anymore. Now lets see if it can build some convection around the center.

Anywho, I am off to roll a few games. See y'all soon. Don't let the little low run off ☺

Quick Links-models, imagery, wind data, and more.

Backing up a little....

Sorry Story, I get your point about palgerism, but it is still nice to have a source, from a viewers point. And as you know, we have had issues with that sort of thing before. Not that you intended it that way though.
Member Since: Agosto 17, 2005 Posts: 26 Comments: 15218
359. RL3AO 9:10 PM GMT en Mayo 07, 2007    
There is no way thunderstorms are going to get around the center. Way too much dry air, not enough time.
360. StormJunkie 9:11 PM GMT en Mayo 07, 2007    
RL, I don't think dry air is around the center anymore. It looks like it has cut it off now imho. Still lacks deep convection and has lots of dry air around the system, but the moisture has been on the increase around the center all day.
Member Since: Agosto 17, 2005 Posts: 26 Comments: 15218
361. StoryOfTheCane 9:12 PM GMT en Mayo 07, 2007    
yeah i agree, definitely will make a point to cite from now on so I dont come off in a way im not intending
362. Tazmanian 9:13 PM GMT en Mayo 07, 2007    
like how small can a watch boxs get? i nevere seen a watch box this small it is vary small

thiz look how cute this watch box is i nevere seen one this small be for

lol
Member Since: Mayo 21, 2006 Posts: 5088 Comments: 111346
363. StoryOfTheCane 9:15 PM GMT en Mayo 07, 2007    
lol thats funny, Taz, we're talkin pinpoint weather prediction here
364. StormJunkie 9:15 PM GMT en Mayo 07, 2007    
Good deal Story and thanks. Sorry I did not get back to you sooner.

Off to bowl! See ya in a bit.
Member Since: Agosto 17, 2005 Posts: 26 Comments: 15218
365. Tazmanian 9:17 PM GMT en Mayo 07, 2007    
Posted By: StoryOfTheCane at 2:15 PM PDT on May 07, 2007.

lol thats funny, Taz, we're talkin pinpoint weather prediction here


so what
Member Since: Mayo 21, 2006 Posts: 5088 Comments: 111346
366. StoryOfTheCane 9:17 PM GMT en Mayo 07, 2007    
its all gravy, good luck
367. RL3AO 9:17 PM GMT en Mayo 07, 2007    
You can see the light shaded box. It was just a computer error.

But the light shaded box isnt even that big.
369. StoryOfTheCane 9:21 PM GMT en Mayo 07, 2007    
lol well they've accomplished that ten fold, that could be the smallest watch area ive ever seen. they put it so far ahead of the approaching storm too....AND now its gone...AND now its back and bigger
371. StoryOfTheCane 9:24 PM GMT en Mayo 07, 2007    
Posted By: Michael at 9:21 PM GMT on May 07, 2007.
Ladies and gentlemen, that is a pre sign of mass destruction in the Gulf later in the year.


Michael, dont be a crazycaster now, come back over to the other side...
373. StoryOfTheCane 9:26 PM GMT en Mayo 07, 2007    
just dont be so graphic with your comments so we can avoid hectic rage in here
374. StoryOfTheCane 9:28 PM GMT en Mayo 07, 2007    
say something like, "it could be an ominous sign of potential gulf landfalls", or something along those lines
376. RL3AO 9:32 PM GMT en Mayo 07, 2007    
How are a few high altitude clouds across the GOM that are apart of an extra-tropical low off of the east coast a sign of upcoming mass destruction in the Gulf of Mexico?
378. StoryOfTheCane 9:34 PM GMT en Mayo 07, 2007    
i personally think the East Coast is going to see more action than the Gulf Coast this year, but this storm has nothing to do with that assumption.
379. StoryOfTheCane 9:36 PM GMT en Mayo 07, 2007    
we're more than likely going to see a lot of Western Gulf and East Coast landfalls, but thats just my guess dont put too much clout into it
380. weatherboykris 9:37 PM GMT en Mayo 07, 2007    
381. chessrascal 9:39 PM GMT en Mayo 07, 2007    
Link Cape Hatteras buoy
382. RL3AO 9:40 PM GMT en Mayo 07, 2007    
Heres the NWS radar wind velocity from the Greensburg twister.

2
383. StoryOfTheCane 9:40 PM GMT en Mayo 07, 2007    
it is definitely gaining a little convection but not near enough

384. chessrascal 9:40 PM GMT en Mayo 07, 2007    
look at the wave height on the buoy!
386. weatherboykris 9:42 PM GMT en Mayo 07, 2007    
I notice the dry air on that WV image has stopped wrapping into the center,storyofthecane.
Member Since: Diciembre 9, 2006 Posts: 125 Comments: 11343
387. StoryOfTheCane 9:43 PM GMT en Mayo 07, 2007    
yep, the center has definitely closed itself off but its still very dry all around it and I dont see that changing too soon. I think we would have to see this thing go a couple hundred miles further East to be a threat
388. DocBen 9:44 PM GMT en Mayo 07, 2007    
Story - seems like it is getting over a 'sweet spot' of the Gulf Stream and might have warm enough water to develop. What do you think?
Member Since: Mayo 16, 2006 Posts: 0 Comments: 96
389. rxse7en 9:45 PM GMT en Mayo 07, 2007    
WOW! One thing I just noticed...check how the smoke REALLY starts blowing up in the Okeefenokee ---> http://www.ssd.noaa.gov/goes/east/carb/loop-vis.html
Member Since: Agosto 21, 2005 Posts: 0 Comments: 526
390. RL3AO 9:45 PM GMT en Mayo 07, 2007    
Its starting to look alot better. Lets see how it looks in the morning.
391. StoryOfTheCane 9:46 PM GMT en Mayo 07, 2007    
hey ive seen crazier things happen but Im not so sure about that at this point in time, i dont think it has enough continental seperation. If it stays stationary for awhile it may be able to muster the energy so it is still worth watching nonetheless
392. RL3AO 9:46 PM GMT en Mayo 07, 2007    
Thats crazy rxse. You can really see the smoke.
393. weatherboykris 9:47 PM GMT en Mayo 07, 2007    
Posted By: StoryOfTheCane at 9:43 PM GMT on May 07, 2007.

yep, the center has definitely closed itself off but its still very dry all around it and I dont see that changing too soon. I think we would have to see this thing go a couple hundred miles further East to be a threat


Look,maybe I need to reiterate here.I do not think this will be a threat to anyone more than it already is.I think at most it will be an STS.Just so you know,I'm not being a wishcaster here.
Member Since: Diciembre 9, 2006 Posts: 125 Comments: 11343
394. StoryOfTheCane 9:50 PM GMT en Mayo 07, 2007    
sorry kris didnt mean to seem like i was implicating you were, i meant threat as becoming a named storm and didnt mean for it to have any reference to you whatsoever
395. weatherboykris 9:53 PM GMT en Mayo 07, 2007    
ok,no problem.
Member Since: Diciembre 9, 2006 Posts: 125 Comments: 11343
396. 1900hurricane 9:55 PM GMT en Mayo 07, 2007    
Hello y'all!
Member Since: Agosto 2, 2006 Posts: 43 Comments: 10366
397. StoryOfTheCane 9:55 PM GMT en Mayo 07, 2007    
the Visible Caribbean Loop is definitely showing added cloud cover in areas of dry air to the south of the circulation. The closer it gets to Florida the less likely it will become Andrea, but right now it appears to be pulling in moisture

Hello 1900!
399. 1900hurricane 9:59 PM GMT en Mayo 07, 2007    
What's everyone's thoughts on the Bermuda High this year? With the way thing have been turning out so far this year (especally the dryness of the Southeast), I think the High will be stronger this year than average. But, that is just one person's guess...
Member Since: Agosto 2, 2006 Posts: 43 Comments: 10366
400. StoryOfTheCane 10:00 PM GMT en Mayo 07, 2007    
I think the location of the High right now is about the weakest it will get all season
401. Thundercloud01221991 10:01 PM GMT en Mayo 07, 2007    
Floater 4 says "Test Floater- Subtropical System"

so it is a STS

Link
Member Since: Agosto 1, 2006 Posts: 28 Comments: 3670

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About JeffMasters
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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