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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534. HurricaneFCast
11:32 PM GMT on May 06, 2007
Actually, the SST's around the East Coast of Florida are around 80 degrees according to NOAA.
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533. V26R
11:36 PM GMT on May 06, 2007
Hey Bama does this Qualify as Panic Mode yet?
Member Since: July 20, 2006 Posts: 0 Comments: 1762
532. melwerle
11:34 PM GMT on May 06, 2007
any bets on first fight of the year? Where the hell is Storm Top?
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531. Drakoen
11:34 PM GMT on May 06, 2007
weatherguy03 look at Hurricanefcast's post at the top of the page mostly this system will be tropical as it has a warm core. I am very anxious to see what NHC says about it.
Member Since: October 28, 2006 Posts: 57 Comments: 30825
529. Bamatracker
11:34 PM GMT on May 06, 2007
JP...he can say it....just may not be the correct thing to say.
Member Since: May 17, 2006 Posts: 6 Comments: 1367
528. V26R
11:33 PM GMT on May 06, 2007
TWC Ratings must be down, or is it a Rating period for Cable TV???
Member Since: July 20, 2006 Posts: 0 Comments: 1762
527. Bamatracker
11:33 PM GMT on May 06, 2007
woohoo...gas up the hurricane hunters!!!! LOL!!

Going be interesting on here tonight!
Member Since: May 17, 2006 Posts: 6 Comments: 1367
525. MTJax
11:29 PM GMT on May 06, 2007
Relax JP. I dont remember you getting so wound up last year.
BUT I will give you 1008 on Thursday.
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524. V26R
11:31 PM GMT on May 06, 2007
FCast Geez Its just a Broad area of LP forming, Calm down
Member Since: July 20, 2006 Posts: 0 Comments: 1762
523. Drakoen
11:31 PM GMT on May 06, 2007
Posted By: HurricaneFCast at 11:27 PM GMT on May 06, 2007.

Obviously, if the Weather Channel is acknowledging its existence along with the NWS and NHC, then it's something to watch. They are about label it an invest and send a plane. We're startin' early this year folks. Buckle your seatbelts


thats what they said lol? I hope they have something on it at fifty minutes past the hour.
Member Since: October 28, 2006 Posts: 57 Comments: 30825
522. weatherguy03
7:31 PM EDT on May 06, 2007
SST's support Subtropical formation, not tropical development.
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521. StormJunkie
11:30 PM GMT on May 06, 2007
Easy jp, I am not sure SSTs are fine. They are borderline at best imho
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520. Drakoen
11:28 PM GMT on May 06, 2007
Posted By: HurricaneFCast at 11:24 PM GMT on May 06, 2007.

V26R- The weather channel is talking about it right now, They said it's going to form, they are talking to hurricane experts right now, and they are pondering whether it will be tropical or subtropical. It's already warm-core, as Micheal stated, so i believe it will be tropical. It's not the air temp that matters either... it's the water temp(warm enough where it is), moisture content(plenty), low vertical wind shear(it's weakening), and of course, the front itself has formed the low, which is in an environment that has the ability for tropical cyclogenesis. There ya go. Keep an eye on this one for all of you in Florida, Georgia or the Carolinas. I myself am in Florida, Near the Georgia border, we need this rain, the fire in Ware County fire is horrible, we need rain now.

yes thanks for making this post. And its gonna be an invest soon. EVerything is happening so fast and getting really exciting as predicitions about an active 2007 storm season are following thorough. I shoudl have watched the WTC i would have really like what they had to say personally for my self.
Member Since: October 28, 2006 Posts: 57 Comments: 30825
519. weatherguy03
7:28 PM EDT on May 06, 2007
An Invest, Planes?? Take it easy!..LOL The most we will get out of this is a Hybrid type storm, maybe Subtropical in nature. Think of it more like a winter Gale. Gonna be bad for Marine interests along the Southeast coast. Now will we see an Invest out of this, possibly.
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518. HurricaneFCast
11:28 PM GMT on May 06, 2007
V26R- It's not forming off the Carolinas.. it's off the coast of Florida right now.... The environment is definitely more conducive for development near Florida than the Carolinas, so your ideology concerning the theory of a Carolina T-Storm is correct. However, it's located much further south than that.
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517. Bamatracker
11:28 PM GMT on May 06, 2007
Alright who is going to monitor TWC to see when Abrams and Cantore get deployed. We know its the real deal then LOL!!!
Member Since: May 17, 2006 Posts: 6 Comments: 1367
516. V26R
11:28 PM GMT on May 06, 2007
Oh MT Leave Poor Jim to his Baldness Misery
Member Since: July 20, 2006 Posts: 0 Comments: 1762
514. MTJax
11:27 PM GMT on May 06, 2007
Sorry HurricaneFCast, as you see, we have lost faith in TWC a loooong time ago. About the same time Cantore lost his hair.
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513. HurricaneFCast
11:27 PM GMT on May 06, 2007
I've got a link to the latest GFS run.. take a look, it shows a semi-strong Low Pressure System forming. Link
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512. RL3AO
6:27 PM CDT on May 06, 2007
Dont mention the T word (tropical). We wouldnt want CNN to break in talking about possible evacuations after TD1 forms. :)
511. V26R
11:27 PM GMT on May 06, 2007
Ahh Next Time Roman!!!
Member Since: July 20, 2006 Posts: 0 Comments: 1762
510. HIEXPRESS
11:27 PM GMT on May 06, 2007
Statement as of 7:22 PM EDT on May 06, 2007

The National Weather Service in Miami has issued a

* Tornado Warning for...
western Broward County in South Florida.
Extreme southwestern Palm Beach County in South Florida.
Southeastern Hendry County in South Florida.
East central Collier County in South Florida.

* Until 815 PM EDT

* at 716 PM EDT... National Weather Service Doppler continue to
radar indicated a severe thunderstorm capable of producing a
tornado near Big Cypress Seminole Indian reservation... moving
southeast at 30 to 35 mph.

This storm is also capable of producing Golf Ball size hail... and
damaging winds in excess of 60 mph.

* The tornado will be near...

Miccosukee service Plaza by 740 PM EDT
intersection Alligator alley and Miami canal by 755 PM EDT

When a Tornado Warning is issued based on Doppler radar... it means
that strong rotation has been detected in the storm. A tornado may
already be on the ground... or could possibly develop anytime. If you
are in the path of this dangerous storm... move indoors and to the
lowest level of the building. Stay away from windows. If driving... do
not seek shelter under a Highway overpass.

Report severe weather or damage to the nearest law enforcement agency
or your County emergency management. They will relay your report to
the National Weather Service forecast office in Miami. Or you can
also call the National Weather Service in Miami directly at
305.229.4528 to report severe weather.

A Severe Thunderstorm Watch remains in effect until 800 PM EDT Sunday
evening for southern Florida.

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509. V26R
11:24 PM GMT on May 06, 2007
Well if you will look at the Bouys near the COC
you'll notice that the pressure has steadied off
And we all know how Accurate the Weather Channel is with their forecasts, Its just too early for something to form off the Carolinas
It'll be a Noreaster for Georges Bank and Nova Scotia!
Member Since: July 20, 2006 Posts: 0 Comments: 1762
508. StormJunkie
11:24 PM GMT on May 06, 2007
Evening Jax

So you are saying that there is no chance that a subtropical storm forms? If so then why not?

Aren't the upper air conditions supposed to get better in the next 48hrs or so?
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507. Bamatracker
11:26 PM GMT on May 06, 2007
TWC is showing it...uh oh. We are about to go into panic mode
Member Since: May 17, 2006 Posts: 6 Comments: 1367
506. HurricaneFCast
11:25 PM GMT on May 06, 2007
Obviously, if the Weather Channel is acknowledging its existence along with the NWS and NHC, then it's something to watch. They are about label it an invest and send a plane. We're startin' early this year folks. Buckle your seatbelts.
Member Since: Posts: Comments:
505. weatherguy03
7:25 PM EDT on May 06, 2007
Dang, TWC is talking about it. There goes the chances of this thing forming!..LOL
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504. MTJax
11:24 PM GMT on May 06, 2007
And Hi again, Pap, Junkie, JP, Taz, Doc, Bama,23 and others!!
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503. HurricaneRoman
11:23 PM GMT on May 06, 2007
too late for pictures.... rain started and the warning was allowed to expire anywayz
Member Since: February 25, 2006 Posts: 2 Comments: 959
502. HurricaneFCast
11:24 PM GMT on May 06, 2007
MTJax.. read my post i just posted. Please.
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501. HurricaneFCast
11:15 PM GMT on May 06, 2007
V26R- The weather channel is talking about it right now, They said it's going to form, they are talking to hurricane experts right now, and they are pondering whether it will be tropical or subtropical. It's already warm-core, as Micheal stated, so i believe it will be tropical. It's not the air temp that matters either... it's the water temp(warm enough where it is), moisture content(plenty), low vertical wind shear(it's weakening), and of course, the front itself has formed the low, which is in an environment that has the ability for tropical cyclogenesis. There ya go. Keep an eye on this one for all of you in Florida, Georgia or the Carolinas. I myself am in Florida, Near the Georgia border, we need this rain, the fire in Ware County fire is horrible, we need rain now.
Member Since: Posts: Comments:
500. MTJax
11:20 PM GMT on May 06, 2007
Greetings fellow bloggers.
You guys are killin me. :)
There are no tropical storms/hurricanes forming off the South East. The air, water, winds, pressure, and temperatures do not support any theory in these areas. The storms will come soon enough.
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499. melwerle
11:20 PM GMT on May 06, 2007
ok - that's not good...i keep looking at the different scenarios and a bunch of them keep showing it hitting georgia dead on. hmmm...keep it to RAIN only. I am not at all ready for anything other than a bit of rain and wind right now!

Time to rig the sailboat perhaps and be like Gary Sinese in Forest Gump...
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498. StormJunkie
11:22 PM GMT on May 06, 2007
RL, you can find it under the model pages listed here. Lots of other good links there too.
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497. RL3AO
6:21 PM CDT on May 06, 2007
Wheres the cyclone genesis probabilty page located?
496. V26R
11:18 PM GMT on May 06, 2007
Thats gotta be a record JP
Member Since: July 20, 2006 Posts: 0 Comments: 1762
495. Patrap
6:09 PM CDT on May 06, 2007
0
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493. Tazmanian
4:16 PM PDT on May 06, 2007
TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN MAY 06 2007

FROM A 1012 MB SFC LOW NEAR
THE OUTER BANK TO SOUTH GEORGIA
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492. StormJunkie
11:15 PM GMT on May 06, 2007
mel it is a cyclone genesis map. I think blue is like .6% chance of something forming...lol
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491. Bamatracker
11:15 PM GMT on May 06, 2007
meaning .4 to .7% chance of tropical development in that area
Member Since: May 17, 2006 Posts: 6 Comments: 1367
490. Bamatracker
11:14 PM GMT on May 06, 2007
nooooooooo........boooooooooooo!!! Blue squares bad!!!
Member Since: May 17, 2006 Posts: 6 Comments: 1367
489. melwerle
11:12 PM GMT on May 06, 2007
ok - i'm not educated with the blue square - meaning please? Sorry - trying to catch up with the learning curve....
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488. StormJunkie
11:12 PM GMT on May 06, 2007
Good to see ya skye and stl

I have been checking that on and off, but that is the first I saw of the blue square....
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487. RL3AO
6:13 PM CDT on May 06, 2007
Woohoo! Blue square!
486. V26R
11:12 PM GMT on May 06, 2007
Think you guys are jumping the gun on this one
Air temps are still too cool out that way for anything to blow up
Member Since: July 20, 2006 Posts: 0 Comments: 1762
485. Skyepony (Mod)
11:10 PM GMT on May 06, 2007
STL~ Looked at that not 10 mins ago, they just added that blue square.
Member Since: August 10, 2005 Posts: 225 Comments: 39381

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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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