Greensburg tornado an EF-5; coastal storm will bring 3-5' storm surge to Carolinas

By: Dr. Jeff Masters , 14:42 GMT le 07 mai 2007

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
Storm Cloud Formation (FT2)
Detail of Turbulance Under the Trough on 05/06/2007 in SE Iowa.
Storm Cloud Formation

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1025. stormwatcher247
01:12 GMT le 10 mai 2007
So, what's the remainder of the tropics look like?
1024. lightning10
03:17 GMT le 09 mai 2007
RIP griffiths observatory. Record heat + wind + DRYEST SEASON TO DATE...

Member Since: 24 novembre 2005 Posts: 41 Comments: 630
1022. Patrap
15:35 GMT le 08 mai 2007
..from 0930 am CST last entry 5 30 frame loop..The showers earler were taking on some banding organazation. But now .. in the latest few frames, its less organised and somewhat pocketed. It may however ,,get the structure going this afternoon. Time will tell
Member Since: 3 juillet 2005 Posts: 454 Comments: 144373
1021. SCwxwatch
14:53 GMT le 08 mai 2007
Posted By: thelmores new blog!!!!

Isnt it due anytime?
1020. thelmores
14:52 GMT le 08 mai 2007
new blog!!!!
Member Since: 8 septembre 2005 Posts: 0 Comments: 3833
1019. seminolesfan
14:50 GMT le 08 mai 2007
EXTREMELY well put incongN!! ;)
Member Since: 14 juin 2006 Posts: 0 Comments: 2154
1018. thelmores
14:50 GMT le 08 mai 2007
"Very subjective"

finally, somebody that gets my point!

I say blue, you say green! LOL
Member Since: 8 septembre 2005 Posts: 0 Comments: 3833
1017. Jedkins
14:49 GMT le 08 mai 2007
well you can't be sure, but local guys have rain season pattern here by friday into next week, which normally isn't till june. So maybe tropical weather is off to an early start.

Hard to tell for sure just yet.
1016. thelmores
14:49 GMT le 08 mai 2007
Pat...... keep that up, and anybody on dial-up will get peeved! LOL

1MB download on your "loop"...... 3-5 minute download on dial-up....

course I think we do have an image-less blog also don't we?? If I were dial-up, thats what i would be looking at!

but I guess as long as nobody complains.......
Member Since: 8 septembre 2005 Posts: 0 Comments: 3833
1015. incogNeato
14:46 GMT le 08 mai 2007
The arguing about the status of the storm is pretty humorous... it defines the world of subtropical storms! How "subtropical" does it need to be to be called "subtropical". I don't think there's a soul on here who could possibly argue that it is either 100% tropical or 100% extratropical. The question is, how much is enough to call it subtropical? Very subjective, IMO. Given its virtually complete frontal disconnect this morning, I'd say it crosses the threshold for my opinion. But with the disorganization of the convection and lack of much near the center... I can certainly see the opposing opinion - the one to which NHC is apparently subscribing. Subtropical storms are such a joy.
1014. ForecasterColby
14:46 GMT le 08 mai 2007
No hard feelings, agreed. I'm off for an AP exam, will be back later. /cheer for Andrea!
1013. Chocolatethunder
14:46 GMT le 08 mai 2007
Is it me or are we starting to see a prelude to an active season of tropical weather?
1012. thelmores
14:44 GMT le 08 mai 2007
Kman..... you'd have a tough time getting "anything" by this crowd! LOL
Member Since: 8 septembre 2005 Posts: 0 Comments: 3833
1010. Patrap
14:43 GMT le 08 mai 2007
Member Since: 3 juillet 2005 Posts: 454 Comments: 144373
1009. thelmores
14:43 GMT le 08 mai 2007
"CAT 1 landfall near Savannah."

no fair! I called Savannah yesterday! LOL
Member Since: 8 septembre 2005 Posts: 0 Comments: 3833
1008. kmanislander
14:43 GMT le 08 mai 2007
90L is now up on the Navy site.
Don't know if anyone has posted this yet so apologies if you all know this
Member Since: 19 août 2006 Posts: 0 Comments: 16811
1007. rxse7en
14:42 GMT le 08 mai 2007
LOL! @ GulfScotsman. Love it when the easily-angered get tormented...or is that a real prediction? :D

Member Since: 21 août 2005 Posts: 0 Comments: 703
1006. SCwxwatch
14:41 GMT le 08 mai 2007
Jedkins this is a blog!

The only person being childlike is you!

A blog is meant for conversation, nowhere in the introduction of this blog does it remotley mention this is a Professional or experts blog.

Get your head out of your arse and quit acting like your some sort of professional , because we can all see through your idiotic antics.

We are all here for discusion you seem to be the only one who wants to argue.

Now be gone Troll!!
1005. Jedkins
14:41 GMT le 08 mai 2007
1004. Levi32
14:41 GMT le 08 mai 2007
This blog is already going down the slippery slope that it was last year....

No one wants to listen to anyone else. And now the arguing sets in. Gee wiz guys. Pull it together. Do you really think anyone is going to want to read this to get info when major hurricanes are making landfall in August??
Member Since: 24 novembre 2005 Posts: 635 Comments: 26780
1003. Jedkins
14:41 GMT le 08 mai 2007
Hey look at last few sattelite frames, looks like its headed for Florida, it might just be a job, but its worth watching further.
1002. Chocolatethunder
14:40 GMT le 08 mai 2007

Al just makes me laugh........I love the weather
1001. Jedkins
14:39 GMT le 08 mai 2007
Levi is right on target folks, I have been a little harsh I admit, but please understand what I have stated, and I rest my case from here.
999. Levi32
14:37 GMT le 08 mai 2007
Ok, here's MY piece of rock-hard evidence to tell whether this thing is subtropical or not. Just look at the convection, that's all you have to do. Is the convection forming by baroclinic processes? The answer is yes, but it's starting to convert to tropical processes. How do I know this? Well before this morning the convection was just individual cells popping up anywhere and not really covering anything, which indicates baroclinic processes were still responsible. This morning the t-storms are starting to form little bands, which indicates the t-storms are starting to be generated by forced convection. However the thing still doesn't have a CDO, so the tropical process has not completely taken over yet. This is the main thing I am looking at right now. I hope that helps your debate lol. Try and work together guys. It doesn't help to bash each other.
Member Since: 24 novembre 2005 Posts: 635 Comments: 26780
998. Jedkins
14:36 GMT le 08 mai 2007
lol nice job, I guess I better go with the rest of the blind sheep instead of listening to the experts.

I figured you guys could learn patience that its almost there but not quite and we should wait some more.

But unfortunately, you'd rather stay childlike with much impatience.

Oh Lord God almighty what would I do without him...
997. thelmores
14:36 GMT le 08 mai 2007
My first post this morning.....

"Mornin all! :)

Well the so called "experts" can call this storm whatever they want....

I am calling it a sub-tropical storm, cause thats what it is!!!"

I stick by it..... gotta get some work done.... BBL! :)
Member Since: 8 septembre 2005 Posts: 0 Comments: 3833
996. Srt4Man
14:36 GMT le 08 mai 2007
Me too.

If the NWS experts are anything like this blog I would say wagers have been made , and the plane will gather the info needed to name the winners. LOL

Im kidding of course!

You never know that doesnt sound improbable hehe. I know if i were one of the leading experts id have bets down with my coworkers.
995. Comatose
14:35 GMT le 08 mai 2007
Does this thing even have a firm invest number yet?
994. Patrap
14:35 GMT le 08 mai 2007
..'The Charleston Bump is only a small feature on bathymetric maps, but it exerts a strong influence on the Gulf Stream, one of the ocean's most familiar currents. The Gulf Stream parallels the coast as it flows smoothly northward from Florida and the Bahamas, with hardly a churn or ripple visible. Sea surface temperature (SST) data from the Advanced Very High Resolution Radiometer (AVHRR) provides almost daily views of the Gulf Stream -- one Web site that provides images of this data is satellite imagery provided by the Rosenstiel School of Marine and Atmospheric Science in Miami, Florida. Even though SST images show the path of the Gulf Stream on the surface of the ocean, it should be remembered that ocean currents are three-dimensional, and thus they can influence, and be influenced by, the topography of the sea floor'...
Member Since: 3 juillet 2005 Posts: 454 Comments: 144373
993. stampapaul
14:34 GMT le 08 mai 2007
did i mention the smoke in tampa..:o
991. Patrap
14:34 GMT le 08 mai 2007
Food for thought today..The Charleston Bump and the Gulf stream deflections..Link
Member Since: 3 juillet 2005 Posts: 454 Comments: 144373
989. K8eCane
14:33 GMT le 08 mai 2007
jedkins always does this
watch him this season
he poo poos on anything that isnt threatening his territory
Member Since: 26 avril 2006 Posts: 5 Comments: 4193
988. thelmores
14:33 GMT le 08 mai 2007
"(if you were serious, look a few posts above yours)"

Even when Gulf is serious, he IS NOT serious..... kinda like our storm! LOL
Member Since: 8 septembre 2005 Posts: 0 Comments: 3833
987. Jedkins
14:32 GMT le 08 mai 2007
it will be hitting the gulf stream soon from there it probably will gain warm core status which is the only thing keeping this from being subtropical, but heck it could easily attain it.

Lets just wait and see some more.

And yes, thats some decent data, but not enough, lets do a microwave pass on that bad boy, thats the best way to define a system whether it is or isn't when its borderline like this.
986. Patrap
14:32 GMT le 08 mai 2007
As Levi says..its quite cooler SSTs to the Systems west.Time is not on the storms side.
Member Since: 3 juillet 2005 Posts: 454 Comments: 144373
985. Patrap
14:31 GMT le 08 mai 2007
Member Since: 3 juillet 2005 Posts: 454 Comments: 144373
984. Levi32
14:30 GMT le 08 mai 2007
Guys guys cool it now. We're supposed to work together remember? Jedkins is right it is not quite there yet, but it is very close. By this afternoon I think they should name it.

GSM you have to realize that the NHC statement DOES NOT say that they named the storm. It just says that they're watching it, and it's causing high surf on the coast, nothing more.
Member Since: 24 novembre 2005 Posts: 635 Comments: 26780
983. thelmores
14:30 GMT le 08 mai 2007
"don't be so proud, do you have data stating it is? WRONG!!! "

We have data that supports this being a subtropical storm..... I don't get your point Jed....

"it is not, because its not, but its trying to be, so maybe it will"???? ROFL!
Member Since: 8 septembre 2005 Posts: 0 Comments: 3833
982. ForecasterColby
14:30 GMT le 08 mai 2007
"can someone please cut and paste the NHC special advisory statmeent.... please in bold"

(if you were serious, look a few posts above yours)
981. SCwxwatch
14:29 GMT le 08 mai 2007
Posted By: GulfScotsman
shut up jedkins

I concur!
980. Jedkins
14:29 GMT le 08 mai 2007
I do think the NHC needs to check it out at least twice today, no significant organization is expected, but we all know how wrong that can turn, things often go unexpected.
979. ForecasterColby
14:29 GMT le 08 mai 2007
Okay, Jedkins, I'll bite: do you have hard data telling you it's not.

My data is as follows:

- Bouy reports indicating a reasonably symmetric windfield
- Convection near the center
- Precipitation in said convection as shown by Charleston radar
- 26C waters very near the storm in the gulf stream
- No visible connection to a front.
978. Levi32
14:28 GMT le 08 mai 2007
Just don't forget guys, the I-told-you-sos can't be said yet until Andrea actually forms, if she ever does. This is no guarantee lol. The NHC is just acknowledging that this needs to be watched, which we all knew already :) 90L may run out of time, and the water gets quite cooler once it comes out of the west side of the gulf stream, which may inhibit strengthening right before the coast. We'll see. Definitely interesting.
Member Since: 24 novembre 2005 Posts: 635 Comments: 26780
975. Jedkins
14:25 GMT le 08 mai 2007
don't be so proud, do you have data stating it is? WRONG!!! All you have is sattelite, sorry that don't cut it kiddies.

Its ALMOST there, but still has a little bit more to go, you can't call a tropical storm thats almost a hurricane a hurrican till it is one just because it appears so in every way on sattelite.

I woul expect everyone has learn this by now, I guess the hype factor overpowers that thought.

So as Ive stated many times, its ALMOST there, just give it a bit longer, but don't call it something it isn't till it actually is. I know its fun, but considering yall are petty serious about it, lets be real.

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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather

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