Dr. Jeff Masters' WunderBlog

Another wild night in Tornado Alley
Posted by: Dr. Jeff Masters, 11:40 AM GMT on May 06, 2007 +6
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
Categories: Tornado
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851. rxse7en 12:25 PM GMT on May 07, 2007    
Hope we get TD1 and it just dumps rain over Jax for a couple of days. So dry here.
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852. K8eCane 12:38 PM GMT on May 07, 2007    
ok sprinkle bottom
are you stormtop?
your name is just the opposite
stormtop/sprinklebottom
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853. Patrap 12:44 PM GMT on May 07, 2007    
7
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854. SPRINKLEBOTTOM 12:49 PM GMT on May 07, 2007    
K8 I AM THE ANTI-STORMTOP. I AM THE KING OF C & P. EVERYTHING I SAY IS WRITTEN IN SAND. IN EVERY POST THERE WILL BE A MESSAGE IN THE MOST IRREVERENT WAY. I CARE BECAUSE I DON'T CARE
855. thelmores 12:50 PM GMT on May 07, 2007    


morning all! :)

Very interesting indeed...... at least at this point, seems extra, or sub tropical, as it seems the highest winds are well removed from the center. Quite breezy in myrtle beach this morning.... Steady north wind at 10-15mph, with gusts to 30+......

will be interesting to watch this "storm" develop over the next couple days..... wish we could get a little rain outta this "sucka"......

could this be tropical storm Andrea??
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856. K8eCane 12:51 PM GMT on May 07, 2007    
ok sprinklebottom
are you gonna stay on WU this season?
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857. seminolesfan 12:53 PM GMT on May 07, 2007    
sprinkleb-if you're the anti-ST then you should completely avoid capital letters; don't worry we're listening, you don't have to yell. lol
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858. K8eCane 12:56 PM GMT on May 07, 2007    
lol right seminoles
stormtop uses all caps all the time
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859. shoals 12:57 PM GMT on May 07, 2007    
Check this out- a webcam in Rodanthe, NC. notorious area for erosion on Hatteras Island;
http://www.darenc.com/webcam/mirlo.php

I live in Hatteras and we had gusts over 60 mph late last night, still gusting over 40-50 mph this morning.
860. thelmores 1:00 PM GMT on May 07, 2007    
Station 41001 - 150 NM East of Cape HATTERAS
(7:50 am EDT)
Wind Direction (WDIR): ENE ( 70 deg true )
Wind Speed (WSPD): 42.7 kts
Wind Gust (GST): 52.4 kts
Wave Height (WVHT): 37.1 ft

37FT WAVES! LOL

THE SURF IS UP! LOL
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861. ForecasterColby 1:02 PM GMT on May 07, 2007    
ST2.5 in from SSD on our new friend 90L!

Wooo hoo, let's get this show on the road, folks.
862. seminolesfan 1:02 PM GMT on May 07, 2007    
Anyone else see the 00z ECMWF? It's the first model I've seen that pushes this thing across FL and into the Gulf.

The others(CMC,NOGAPS,UKMET,GFS)I looked at are still going with the loop then moving off to the E or NE, so the concensus is NOT into the Gulf right now.

I just thought it was worth mentioning.
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863. Patrap 1:03 PM GMT on May 07, 2007    
6
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864. seminolesfan 1:04 PM GMT on May 07, 2007    
Your not saying that it is now an invest are you Colby?
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865. thelmores 1:06 PM GMT on May 07, 2007    
Colby, we have 90L now???
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868. Patrap 1:12 PM GMT on May 07, 2007    
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869. K8eCane 1:13 PM GMT on May 07, 2007    
LOLOL gulf
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870. ForecasterColby 1:15 PM GMT on May 07, 2007    
NRL hasn't posted it as 90L yet, but this T-number came in an hour or so ago from SSD:

07/1145 UTC 32.0N 73.1W ST2.5/2.5 90L -- Atlantic Ocean

So they're calling it 90L.
871. K8eCane 1:16 PM GMT on May 07, 2007    
90L yay!
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872. ForecasterColby 1:17 PM GMT on May 07, 2007    
By the way, since my site has become overwhelmed with spambots, I'll be posting my thoughts in my blog. Posting 90L statement momentarily.
873. Snowfire 1:23 PM GMT on May 07, 2007    
It'a official--Greensburg has been classified as EF-5. Maximum winds estimated at 205 mph.
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874. hurricane23 1:26 PM GMT on May 07, 2007    
Good morning....

Checking in from work and everything looks like we will indeed have sub-tropical storm in our hands pretty soon.Be back in 3 hours.

gggg
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875. Patrap 1:28 PM GMT on May 07, 2007    
LSU Earth Scans Lab
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876. thelmores 1:28 PM GMT on May 07, 2007    
what does the storm off the SE coast need to become named??? I guess we are looking for tropical characteristics???

we certainly have winds that support a named storm! and 37foot waves to boot!
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877. StormJunkie 1:29 PM GMT on May 07, 2007    
Morning all.

Thel, with the size of that rain shield, we may be able to get some. System really needs to get that dry air out though if it is to become much.

Quick Links - Models, imagery, marine data, and more.
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878. Thundercloud01221991 1:30 PM GMT on May 07, 2007    
LOOK AT THIS

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879. crownwx 1:31 PM GMT on May 07, 2007    
Do u have a link to the SSD classification of a 2.5 for this system?
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882. Skyepony (Mod) 1:34 PM GMT on May 07, 2007    
It isn't an invest. If this was any other basin save the EPAC perhaps...

As for the models 06Zgfs, 00Z NOGAPS, UKMET, MRF & ECMWF all take it over & or disapate it in FL (mostly Northern to central).

CMC & GEM has it meander NFL, GA, SC & out to sea.

A TD looks a little less likely. Maybe STD.
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883. sporteguy03 1:34 PM GMT on May 07, 2007    
Why would it weaken before hitting land? I thought it needs to hit land to weaken??
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884. Patrap 1:35 PM GMT on May 07, 2007    
6
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887. Patrap 1:36 PM GMT on May 07, 2007    
The GFSx does the same Skyepony..this no drought buster..sadly..Link
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889. crownwx 1:39 PM GMT on May 07, 2007    
Colby: Where did you see the SSD classification of 2.5. Where can I find it on the internet?? Thanks
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890. thelmores 1:40 PM GMT on May 07, 2007    
did somebody say west??? LOL
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891. SavannahStorm 1:44 PM GMT on May 07, 2007    
The only name I'm giving this thing is the "Great Waycross Fire-Fanner". Thanks to this windbag another 20,000 acres are gonna go up in flames.
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892. Skyepony (Mod) 1:45 PM GMT on May 07, 2007    
Hey Colby~ sorry about your site.. ST2.5 is near an STS. They are really trying hard to ignore this.

Crown~ link here

Patrap~ yeah we're so dry it's gonna take a few of these.. We're like 15" or so behind here.

Member Since: August 10, 2005 Posts: 144 Comments: 29283
893. Patrap 1:47 PM GMT on May 07, 2007    
Skye,..yall Need a good Meso like we had last Friday..or Gullywashing frog strangling TD..say around May 18th?..
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894. franck 1:51 PM GMT on May 07, 2007    
Patrap...what that is, map?
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895. Tazmanian 1:52 PM GMT on May 07, 2007    
when is the naxt update for the navy site? may be will see 90L or are 1st name storm then
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896. Patrap 1:52 PM GMT on May 07, 2007    
The UNISYS GFSx Home Page..Link
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897. PensacolaDoug 1:55 PM GMT on May 07, 2007    
The "Blue Angels" just took off......They're gonna intercept it.....

No storms in the gulf this year.... and no westcasting...
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898. thelmores 2:03 PM GMT on May 07, 2007    
Taz,

the Navy can update anytime..... I agree with Skye..... they are doing their best to ignore 9OL!

There have already been at least a couple distress calls from ships off the outer banks.... one ship being battered by 34 foot waves!

3 people were in a life raft! talking about a bad day!
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899. Thundercloud01221991 2:05 PM GMT on May 07, 2007    
I wonder what the NWS is going to say about it at 2 00 this afternoon I wonder if it is going to be a special feature
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900. StormJunkie 2:05 PM GMT on May 07, 2007    
It would be a real nasty day to be off shore up that way thel even in a cutter, much less a dingy!

That area really gets churning when the waves and winds get this way.
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901. thelmores 2:06 PM GMT on May 07, 2007    
hopefully Dr. Masters will give us his thoughts on the first Navy invest this morning.....

WAKE UP DR. MASTERS! LOL
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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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