Violent EF-4 tornado causes severe damage at St. Louis' airport

By: Dr. Jeff Masters , 3:25 PM GMT on April 23, 2011

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A violent EF-4 tornado ripped through St. Louis near 8pm local time Friday night, severely damaging Lambert International Airport. The airport, the world's 30th busiest, may be closed for several days. The tornado ripped off the roof from Concourse C, blew out more than half of the windows in the main terminal, and moved an aircraft that was parked at a gate twenty feet. So far, only minor injuries due to flying glass have been reported from the tornado. The tornado also passed over nearby residential areas, causing severe damage. The National Weather Service office in St. Louis has rated the damage from the St. Louis tornado EF-4, making the twister the first violent EF-4 tornado of the year. Softball-sized hail also pelted three towns in Missouri--Hermann, Big Spring, and Warrenton--during Friday night's severe weather outbreak. NOAA's Storm Prediction Center logged 24 tornado reports Friday in Oklahoma, Arkansas, Missouri, Illinois, and Kentucky. The cold front responsible for triggering last night's severe weather will remain draped over the nation's mid-section for the next three days, and a slight risk of severe weather is predicted along a swath from Texas to Ohio both Saturday and Sunday. A more substantial risk of severe weather is likely on Tuesday through Wednesday, as a new, more powerful spring storm system gathers strength over the Midwest.


Figure 1. Radar reflectivity image of the EF-4 St. Louis tornado taken near 8pm local time on Friday, April 22, 2010. This image is from the high-resolution Terminal Doppler Radar (TDR) at the St. Louis Airport, and shows very fine details of the tornado, which displays a classic hook echo here.


Figure 2. Radar Doppler velocity image of the St. Louis tornado taken near 8pm local time on Friday, April 22, 2010. This image is from the high-resolution Terminal Doppler Radar (TDR) at the St. Louis Airport, located at the "+" sign on the image. Green colors denote areas where precipitation is moving towards the radar, and red and yellow colors show where precipitation is moving away from the radar. Pink colors are bad data regions. The small couplet of greens right next to reds is where the tornado was, since the tight vortex had winds moving towards the radar and away from the radar. The area marked "RFD" shows where a Rear-Flank Downdraft (RFD) was occurring behind the tornado. The downdraft hit the ground to the west of the radar site and spread out in all directions, creating a diverging area of winds moving both towards and away from the radar. An area of air flowing into the tornado on the SE side is marked "Inflow." Thanks go to Dr. Rob Carver, wunderground's tornado expert, for annotating this image.


Figure 3.
Remarkable video from a security camera at the St. Louis airport showing the roof being torn off Concourse C.


Figure 4. Severe damage characteristic of at least a strong EF-2 tornado is apparent from this helicopter view of residential St. Louis neighborhoods taken by KMOV.

Jeff Masters

Lambert St. Louis Tornado Damage (WindyCityBob)
Taken after the good friday tornado at Lambert Field St.Louis, MO
Lambert St. Louis Tornado Damage

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Quoting beell:
Post 328, 345,Levi and Pat...
Is there that much difference in the location of the loop between the initial velocity run and IR?

Ya'll looking at apples and oranges?


It's weird Beell, a lot of the navy's model runs look very different from the initial conditions sometimes.

Compare the NLOM initialization with the (I think more accurate) HYCOM initialization:

NLOM:



HYCOM:




And then Pat's image says HYCOM on it, but there's no way it moves the loop that far west in 120 hours. That's not realistic.
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Quoting Levi32:


Yeah that's my bad. I had that wrong in my head for some reason.

That list you posted from Weather456 is the only written record I can even find of tropical wave dates. One would think it would be useful to keep a record or a seasonal count of them for climatology purposes.
I completely agree, that's why i have kept it up and running(filled out) since 2009. Going to keep track of it as much as I can... But seriously it's pretty interesting, how that "pattern" set up.
Member Since: October 3, 2010 Posts: 40 Comments: 4129
Quoting HurricaneDean07:
As of the past 6 years of tracking the first wave off of Africa, they have all occurred in Early May to Mid/Late May.
2004: May 21
2005: May 2
2006: May 11
2007: May 21
2008: May 2
2009: May 13
2010: May 2
2011: unknown

So as of what you can see here the first active year has a later Wave date than the 2nd active year from the active seasons of(2004 to 2005; 2007 to 2008) What i think has happend from recording and observing the activities of the 2 active years that come back to back when they occur, is that the 1st active season is like the primer(it has less storms, and less or the same amount of US landfalls. The 2nd year tend to have many more storms and hurricanes, but i believe 2010 has reversed the pattern and 2011 will be more active US activity wise, like it should be in the 2nd active year, but the 2011 season will be less active. in addition, from how its going right now, I'm going to go ahead and throw this out there, if my pattern observation is true, 2011's first wave will come off of Africa May 21 or 2, depending on how this pattern plays out. If the 1st wave comes off on the 2nd, I would be concerned that 2011 could continue the pattern and pull out to be the 2nd most active hurricane season on record... or 1st... no tellin...


Just asking a question? But, the above dates are waves that came off Africa and developed into something. Otherwise i could find a Wave coming off Africa today and say that is the first wave. I don't mean to come across combative but, asking a question as to what a first wave off Africa really means and when one can say this is the first wave. Hope you understand what i saying and asking!
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Quoting TampaSpin:



I don't think many developing systems roll off Africa that has much meaning! Most development of anything meaningful is local bread stuff near the GOM or SW Caribbean. Am i wrong?


I think that is a given, but he said nothing about development. He said we should be watching for our first tropical wave, which does not imply development.
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Quoting HurricaneDean07:
As of the past 6 years of tracking the first wave off of Africa, they have all occurred in Early May to Mid/Late May.
2004: May 21
2005: May 2
2006: May 11
2007: May 21
2008: May 2
2009: May 13
2010: May 2
2011: unknown

So as of what you can see here the first active year has a later Wave date than the 2nd active year from the active seasons of(2004 to 2005; 2007 to 2008) What i think has happend from recording and observing the activities of the 2 active years that come back to back when they occur, is that the 1st active season is like the primer(it has less storms, and less or the same amount of US landfalls. The 2nd year tend to have many more storms and hurricanes, but i believe 2010 has reversed the pattern and 2011 will be more active US activity wise, like it should be in the 2nd active year, but the 2011 season will be less active. in addition, from how its going right now, I'm going to go ahead and throw this out there, if my pattern observation is true, 2011's first wave will come off of Africa May 21 or 2, depending on how this pattern plays out. If the 1st wave comes off on the 2nd, I would be concerned that 2011 could continue the pattern and pull out to be the 2nd most active hurricane season on record... or 1st... no tellin...


Yeah that's my bad. I had that wrong in my head for some reason.

That list you posted from Weather456 is the only written record I can even find of tropical wave dates. One would think it would be useful to keep a record or a seasonal count of them for climatology purposes.
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Quoting Patrap:
If something spins up soon in the BOC and drifts Nne ,,lotsa phunny tings could get interesting.
real phunny tings yep
Member Since: July 15, 2006 Posts: 178 Comments: 56141
358. JRRP
Link
700hpa relative vorticity
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357. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15684
355. beell
Quoting TampaSpin:



I don't think many developing systems roll off Africa that has much meaning! Most development of anything meaningful is local bread stuff near the GOM or SW Caribbean. Am i wrong?


The assertion was: It is time to start looking for tropical waves off Africa in a few weeks.

Development is another issue.
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Remains of Invest 91L... not to worry


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Quoting Levi32:


No. Our first tropical wave usually comes off in late April or early May.
As of the past 6 years of tracking the first wave off of Africa, they have all occurred in Early May to Mid/Late May.
2004: May 21
2005: May 2
2006: May 11
2007: May 21
2008: May 2
2009: May 13
2010: May 2
2011: unknown

So as of what you can see here the first active year has a later Wave date than the 2nd active year from the active seasons of(2004 to 2005; 2007 to 2008) What i think has happend from recording and observing the activities of the 2 active years that come back to back when they occur, is that the 1st active season is like the primer(it has less storms, and less or the same amount of US landfalls. The 2nd year tend to have many more storms and hurricanes, but i believe 2010 has reversed the pattern and 2011 will be more active US activity wise, like it should be in the 2nd active year, but the 2011 season will be less active. in addition, from how its going right now, I'm going to go ahead and throw this out there, if my pattern observation is true, 2011's first wave will come off of Africa May 21 or 2, depending on how this pattern plays out. If the 1st wave comes off on the 2nd, I would be concerned that 2011 could continue the pattern and pull out to be the 2nd most active hurricane season on record... or 1st... no tellin...
Member Since: October 3, 2010 Posts: 40 Comments: 4129
Quoting Thundercloud01221991:


although 1000 of them is out of reach ... the 543 is getting close...we are at 434 confirmed tornadoes so far
434 confirmed? do you have a link?
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Quoting sunlinepr:
cool pics

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Quoting Levi32:


No. Our first tropical wave usually comes off in late April or early May.



I don't think many developing systems roll off Africa that has much meaning! Most development of anything meaningful is local bread stuff near the GOM or SW Caribbean. Am i wrong?
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347. beell
Post 328, 345,Levi and Pat...
Is there that much difference in the location of the loop between the initial velocity run and IR?

Ya'll looking at apples and oranges?
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Quoting TampaSpin:



WAY to early to look off the coast of Africa!


No. Our first tropical wave usually comes off in late April or early May.
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Quoting HurricaneDean07:
We also have to watch for our first wave to emerge off of Africa in the few weeks...



WAY to early to look off the coast of Africa!
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340. beell
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0350 AM CDT SAT APR 23 2011

VALID 261200Z - 011200Z

...DISCUSSION...
SUBSTANTIAL SEVERE WEATHER POTENTIAL IS EXPECTED TO SHIFT SLOWLY EWD
ACROSS THE ERN U.S. DAYS 4-6 /TUE. 4-26 THROUGH THU. 4-28/...AS A
LARGE UPPER TROUGH PROGRESSES FROM THE CENTRAL U.S. DAY 4 ACROSS THE
MS VALLEY DAY 5...AND THEN ON EWD THROUGH DAYS 6/7. MODEL
DIFFERENCES WITH RESPECT TO TIMING OF THIS FEATURE BEGIN TO EMERGE
DAY 5...BUT BECOME INCREASINGLY PRONOUNCED THROUGH DAYS 6 AND 7 AS
THE TROUGH APPROACHES THE E COAST STATES/ERN ATLANTIC.

THE PRIMARY SEVERE THREAT DAY 4 IS PROGGED FROM E TX NEWD ACROSS THE
ARKLATEX INTO THE MID MS VALLEY
...AS A SHORT-WAVE TROUGH DIGS ESEWD
INTO THIS REGION...WITHIN THE LARGER-SCALE TROUGH. UNSTABLE AIRMASS
COMBINED WITH THE ENERGETIC SHORT-WAVE FEATURE AND ASSOCIATED/STRONG
FLOW FIELD SUGGESTS WIDESPREAD SEVERE WEATHER POTENTIAL -- INCLUDING
RISKS FOR LARGE HAIL...DAMAGING WINDS...AND ISOLATED TORNADOES.


THE THREAT SHOULD SHIFT E OF THE MS VALLEY INTO THE MID
SOUTH/SOUTHEAST DAY 5
...AS THE SHORT-WAVE FEATURE TAKES ON A NEUTRAL
TO EVEN NEGATIVE TILT AS IT CROSSES THIS REGION. AGAIN -- AMPLY
UNSTABLE AIRMASS COMBINED WITH THE STRENGTH OF THE UPPER SYSTEM AND
ASSOCIATED FLOW FIELD SUGGESTS WIDESPREAD SEVERE WEATHER CAN BE
EXPECTED...INCLUDING THE POTENTIAL FOR TORNADOES.


AS MODELS BEGIN DIVERGING SOMEWHAT WITH RESPECT TO TIMING AND
SMALLER-SCALE DETAILS...DEGREE OF THREAT SHIFTING ACROSS THE
APPALACHIANS LATE DAY 5 AND INTO DAY 6 BECOMES LESS CERTAIN.
WHILE
SEVERE WEATHER WILL BE LIKELY WITH THE FRONT EXPECTED TO REACH THE
ATLANTIC COAST BY THE END OF THE PERIOD...WILL REFRAIN FROM
HIGHLIGHTING A THREAT AREA THIS FORECAST
.

WITH THE FRONT LIKELY OFFSHORE BY THE START OF DAY 7... SEVERE
WEATHER POTENTIAL ACROSS THE U.S. APPEARS LESS
WIDESPREAD/SIGNIFICANT AND MUCH MORE UNCERTAIN THROUGH THE END OF
THE PERIOD.
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Quoting Levi32:


A ghost, but precipitation will be picking up in the Caribbean in early May as the MJO looks likely to enter a strong phase over that part of the world.
We also have to watch for our first wave to emerge off of Africa in the few weeks...
Member Since: October 3, 2010 Posts: 40 Comments: 4129
Quoting HurricaneDean07:
we gotta move on now buddy... its dead... very sorry. know you want rain and all, but it wouldn't of made it anyway...
When it gets west or north of here I'll give up hope.... still holding on for some rain showers on Monday!

Member Since: October 25, 2005 Posts: 19 Comments: 22736
Quoting KoritheMan:


I recall a lot of people claiming we'd experience a quick transition to El Nino in the late spring/early summer of 2008, and that obviously never materialized.


May never make it to El Nino. May make it to Neutral and then back to La Nina very possibly! Either way, it does not bold well for this years Hurricane season!
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Wishing all the WUnder bloggers, a most Happy Easter Sunday!
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Quoting RandomText:
Can anyone verify that with an actual rain gauge reading?


Try this list of personal weather stations (PWSes) in Texas. Such stations usually include observed rainfall totals.
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Member Since: August 7, 2010 Posts: 0 Comments: 1957
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Quoting CybrTeddy:


No way we're going to El Nino anytime soon.


I recall a lot of people claiming we'd experience a quick transition to El Nino in the late spring/early summer of 2008, and that obviously never materialized.
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Quoting Levi32:
The insanity continues...



No way we're going to El Nino anytime soon.
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Quoting Patrap:
ESL GOM 120 Hour Surface Current Forecast Model

A Warm water ring has broken off from the Loop


That ring is initialized way too far west, but it does look like it is ready to break off:

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Quoting beell:
Interesting read @ 310, emcf30. Thanks.

I did notice one glaring error.

Tornadoes are measured using the Enhanced Fujita (EF) scale, which is a measure of the maximum winds observed.


Yea I think they left something off the end of that statement.
Member Since: August 7, 2010 Posts: 0 Comments: 1957
Quoting HurricaneDean07:
we gotta move on now buddy... its dead... very sorry. know you want rain and all, but it wouldn't of made it anyway...



Never said it was alive and never gave it a chance at anything....i only had a small window 2 days ago and that was slim!
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Quoting HurricaneDean07:
Hey Levi, What are your thoughts on the GFS already showing another possible formation in the Caribbean on May 2.


A ghost, but precipitation will be picking up in the Caribbean in early May as the MJO looks likely to enter a strong phase over that part of the world.
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If something spins up soon in the BOC and drifts Nne ,,lotsa phunny tings could get interesting.
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What an Incredible active SubTropical Jet this is becoming!
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ESL GOM 120 Hour Surface Current Forecast Model

A Warm water ring has broken off from the Loop
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Quoting TampaSpin:



Wow! This was very well defined!
we gotta move on now buddy... its dead... very sorry. know you want rain and all, but it wouldn't of made it anyway...
Member Since: October 3, 2010 Posts: 40 Comments: 4129
319. beell
Interesting read @ 310, emcf30. Thanks.

I did notice one glaring error.

Tornadoes are measured using the Enhanced Fujita (EF) scale, which is a measure of the maximum winds observed.
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Wow! This was very well defined!
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Quoting HurricaneDean07:
the SOI is extremely high, even though it should be dropping because the equatorial waters of the Pacific have warmed(meaning weaker La nina, more neutral/El nino) So the pattern due to the high SOI will be a la nina pattern, but we will have more of an active pacific year(warmer pacific waters, less shear)
of coarse if you compare it to last year that is...
Member Since: October 3, 2010 Posts: 40 Comments: 4129
Quoting Gearsts:
What do you mean? Insanity??
the SOI is extremely high, even though it should be dropping because the equatorial waters of the Pacific have warmed(meaning weaker La nina, more neutral/El nino) So the pattern due to the high SOI will be a la nina pattern, but we will have more of an active pacific year(warmer pacific waters, less shear)
Member Since: October 3, 2010 Posts: 40 Comments: 4129

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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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