Archive Severe threat April 26-27, 2011

[TW Archive]

mwbwhorton
Posted 26 April 2011 - 11:45 AM

ZCZC SPCPWOSPC ALL
WOUS40 KWNS 261637
ARZ000-LAZ000-MSZ000-OKZ000-TNZ000-TXZ000-270200-

PUBLIC SEVERE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1137 AM CDT TUE APR 26 2011

...AN OUTBREAK OF SEVERE THUNDERSTORMS EXPECTED OVER PARTS OF THE
SOUTHERN PLAINS AND LOWER/MIDDLE MISSISSIPPI RIVER VALLEY LATE THIS
AFTERNOON AND TONIGHT...

THE NWS STORM PREDICTION CENTER IN NORMAN OK IS FORECASTING THE
DEVELOPMENT OF A FEW STRONG/LONG-TRACK TORNADOES AND WIDESPREAD
DAMAGING WINDS OVER PARTS OF THE SOUTHERN PLAINS AND LOWER/MIDDLE
MISSISSIPPI RIVER VALLEY LATE THIS AFTERNOON AND TONIGHT.

THE AREAS MOST LIKELY TO EXPERIENCE THIS ACTIVITY INCLUDE

SOUTHERN HALF OF ARKANSAS
FAR NORTHWEST LOUISIANA
NORTHWEST MISSISSIPPI
FAR SOUTHEAST OKLAHOMA
SOUTHWEST TENNESSEE
NORTHEAST TEXAS

ELSEWHERE...SURROUNDING THE HIGH RISK AREA...SEVERE STORMS ARE ALSO
POSSIBLE FROM PORTIONS OF THE SOUTHERN PLAINS NORTHEASTWARD TO THE
OHIO VALLEY...LOWER GREAT LAKES REGION...AND APPALACHIANS.

AS AN UPPER STORM SYSTEM APPROACHES FROM THE SOUTHWEST UNITED
STATES...THUNDERSTORMS ARE EXPECTED TO DEVELOP BY LATE THIS
AFTERNOON AND EVENING ACROSS PORTIONS OF THE SOUTHERN PLAINS AND
ARKLATEX REGION. WITH A MOIST AND UNSTABLE AIR MASS IN PLACE...THE
STORMS ARE EXPECTED TO RAPIDLY BECOME SEVERE WITH THE POTENTIAL FOR
LONG-TRACK STRONG TORNADOES AND LARGE HAIL. THIS WILL ESPECIALLY BE
THE CASE ACROSS PORTIONS OF NORTHEAST TEXAS...FAR SOUTHERN
OKLAHOMA...FAR NORTHERN LOUISIANA...AS WELL AS MUCH OF ARKANSAS.
ADDITIONALLY...THE THREAT FOR SIGNIFICANT AND WIDESPREAD WIND DAMAGE
WILL ALSO INCREASE LATER TONIGHT...ESPECIALLY DURING THE LATE
EVENING AND OVERNIGHT HOURS ACROSS THE LOWER/MIDDLE MISSISSIPPI
VALLEY INTO THE TENNESSEE VALLEY.

INTO WEDNESDAY...A WIDESPREAD SEVERE WEATHER OUTBREAK...INCLUDING
STRONG TORNADOES...WILL AGAIN BE POSSIBLE. AT THIS TIME...IT APPEARS
THE GREATEST THREAT WILL EXIST ACROSS THE TENNESSEE VALLEY...OHIO
VALLEY...AND SURROUNDING PORTIONS OF THE SOUTHEASTERN U.S.

STATE AND LOCAL EMERGENCY MANAGERS ARE MONITORING THIS POTENTIALLY
VERY DANGEROUS SITUATION. THOSE IN THE THREATENED AREA ARE URGED TO
REVIEW SEVERE WEATHER SAFETY RULES AND TO LISTEN TO
RADIO...TELEVISION...AND NOAA WEATHER RADIO FOR POSSIBLE
WATCHES...WARNINGS...AND STATEMENTS LATER TODAY.

..GUYER.. 04/26/2011
Edited by andyhb, 28 December 2012 - 05:05 PM.

 

[TW Archive]

mwbwhorton
Posted 26 April 2011 - 11:47 AM

SPC AC 261627

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1127 AM CDT TUE APR 26 2011

VALID 261630Z - 271200Z

...THERE IS A HIGH RISK OF SVR TSTMS LATE THIS AFTERNOON INTO
TONIGHT FOR NE TX...FAR SE OK...EXTREME NW LA...THE SRN HALF OF
AR...SOUTHWEST TN...AND NORTHWEST MS...

...THERE IS A MDT RISK OF SVR TSTMS SURROUNDING THE HIGH RISK...FROM
NE TX/SE OK TO THE CONFLUENCE OF THE MS/OH RIVERS...

...THERE IS A SLGT RISK OF SVR TSTMS FROM SRN OK/EAST TX INTO MUCH
OF THE LOWER/MID MS VALLEY...TN AND OH VALLEYS...AND INTO PA/NY...

...AN OUTBREAK OF SEVERE THUNDERSTORMS INCLUDING STRONG TORNADOES
AND WIDESPREAD DAMAGING WINDS IS FORECAST TO OCCUR LATER TODAY AND
TONIGHT...

MORNING WATER VAPOR LOOPS SHOW A BROAD UPPER TROUGH OVER MUCH OF THE
UNITED STATES...WITH TWO SIGNIFICANT SHORTWAVE FEATURES TRACKING
ACROSS THE NATION. THE FIRST TROUGH IS CURRENTLY OVER THE MID MS
AND OH VALLEY AND WILL EJECT NORTHEASTWARD TODAY INTO THE NORTHEAST
STATES. THIS WILL LEAD TO A RELATIVELY LARGE AREA OF POTENTIAL FOR
ISOLATED SEVERE THUNDERSTORMS AS FAR NORTHEAST AS PORTIONS OF NY/PA.
ANOTHER SHORTWAVE TROUGH IS OVER CO/NM AND WILL QUICKLY TRANSLATE
INTO OK/TX BY EVENING. THIS FEATURE IS EXPECTED TO RESULT IN
SIGNIFICANT SEVERE WEATHER OVER THE ARKLATEX AND LOWER/MID MS
VALLEY.

...OK/TX INTO THE LOWER/MID MS VALLEY...
LOW LEVEL MOISTURE IS RAPIDLY RETURNING NORTHWARD THIS MORNING
ACROSS THIS REGION...WITH MID/UPPER 60S DEWPOINTS NOW AS FAR NORTH
AS SOUTHERN AR. THE 12Z FWD RAOB SHOWED A PRONOUNCED CAPPING
INVERSION...WHICH SHOULD INHIBIT STRONG CONVECTIVE DEVELOPMENT UNTIL
MID AFTERNOON. BY THAT TIME...STRONG DAYTIME HEATING AND CONTINUED
MOISTENING OF THE BOUNDARY LAYER WILL YIELD MLCAPE VALUES OF
3000-4000 J/KG AND A WEAKENED CAP OVER NORTHEAST TX/NORTHWEST
LA/SOUTHWEST AR. ISOLATED DISCRETE SUPERCELL THUNDERSTORMS ARE
EXPECTED TO FORM IN THIS REGION...WHICH SHOULD TRACK NORTHEASTWARD
ACROSS SOUTHERN AR/NORTHERN LA DURING THE EVENING. LOW LEVEL WINDS
WILL BE STRENGTHENING DURING THIS PERIOD AS SURFACE CYCLOGENESIS
OCCURS OVER TX...LEADING TO INCREASINGLY FAVORABLE SHEAR PROFILES
FOR TORNADIC ACTIVITY.

MOST MODEL SOLUTIONS SUGGEST A SECOND ROUND OF INTENSE SUPERCELLS
DEVELOP NEAR THE DRYLINE ACROSS NORTH TX AND SOUTHEAST OK BY EARLY
EVENING. THESE STORMS WILL ALSO TRACK EAST-NORTHEASTWARD INTO AR/LA
/ROUGHLY THE SAME AXIS AS THE FIRST WAVE OF STORMS/ AND WILL BE IN A
MUCH MORE FAVORABLE VERTICAL SHEAR PROFILE FOR RISKS OF
STRONG/DAMAGING TORNADOES.

TONIGHT...VERY STRONG LOW LEVEL WINDS ARE FORECAST TO DEVELOP OVER
EASTERN AR/NORTHWEST MS/WEST TN NORTHWARD INTO IL/IND. THERE IS
CONSIDERABLE UNCERTAINTY REGARDING THE EVOLUTION OF STORMS AS THEY
PROGRESS INTO THIS ENVIRONMENT. THE STORMS MAY REMAIN DISCRETE
ACROSS AR WITH A RISK OF STRONG/VIOLENT TORNADOES...OR THEY MAY GROW
UPSCALE INTO A FAST-MOVING BOW ECHO WITH THE RISK OF WIDESPREAD
SIGNIFICANT WIND DAMAGE AND ISOLATED TORNADOES. IN EITHER
CASE...CONDITIONS ARE CLEARLY FAVORABLE A HIGH-END SEVERE WEATHER
EVENT WELL INTO THE NIGHT. FOR THESE REASONS...HAVE EXTENDED THE
HIGH RISK FARTHER EAST.

...TN/OH VALLEY INTO THE NORTHEAST STATES...
THE LEAD SHORTWAVE TROUGH EXTENDS FROM IL/IND INTO MS/AL. A BAND OF
THUNDERSTORMS ASSOCIATED WITH THIS TROUGH HAS BEEN SLOWLY
DIMINISHING THIS MORNING...BUT IS LIKELY TO REJUVENATE BY EARLY
AFTERNOON. WIDESPREAD STRONG MID LEVEL WINDS AND MODERATE CAPE WILL
LEAD TO A RISK OF HAIL AND LOCALLY DAMAGING WINDS OVER A RELATIVELY
BROAD AREA FROM AL/GA NORTHEASTWARD INTO PA/NY. DETAILS ON SPECIFIC
AREAS OF THIS THREAT WILL BE ADDRESSED THROUGH THE DAY IN
FORTHCOMING MESOSCALE DISCUSSIONS.

..HART/GRAMS.. 04/26/2011

CLICK TO GET WUUS01 PTSDY1 PRODUCT

NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
CURRENT UTC TIME: 1646Z (11:46AM), RELOAD THIS PAGE TO UPDATE THE TIME
Edited by andyhb, 28 December 2012 - 05:06 PM.

 

[TW Archive]

pscampbe
Posted 26 April 2011 - 11:56 AM

mwbwhorton, on 26 April 2011 - 11:51 AM, said:

Already posted see my post above...

Sorry. I was editing when you posted yours.

BTW, a new Day 2 is expected in about a half hour. Should be interesting to see how it changes.

 

[TW Archive]

WxFreak
Posted 26 April 2011 - 11:59 AM

That's a pretty good chuck of a high risk....

 

[TW Archive]

trency911
Posted 26 April 2011 - 12:00 PM

p

scampbe, on 26 April 2011 - 11:56 AM, said:

Sorry. I was editing when you posted yours.

BTW, a new Day 2 is expected in about a half hour. Should be interesting to see how it changes.

It will be, should see the Mod get pushed further to the south.

 

[TW Archive]

mwbwhorton
Posted 26 April 2011 - 12:00 PM

noon temp here in Bastrop 82 degrees 72 dewpoint....

 

[TW Archive]

pscampbe
Posted 26 April 2011 - 12:08 PM

Dr. Tim Coleman has an analysis for tomorrow up on the 33/40 blog. Take a look at the model predicted STP for tomorrow at 1 pm.

http://www.alabamawx.com/?p=46153

 

[TW Archive]

brax
Posted 26 April 2011 - 12:12 PM

FFC:

Quote

.UPDATE...
QUICK UPDATE TO TWEAK CURRENT TRENDS AND UPDATE FCST TIMING FOR
TONIGHT THRU THURSDAY. 12Z MODEL RUNS STILL INDICATE SIGNIFICANT
SEVERE WEATHER MOSTLY FOR WED NIGHT. SIG TOR PARAMETER /STP/
VALUES ARE THE HIGHEST I PERSONALLY HAVE EVER SEEN FROM THE GFS OR
NAM WITH VALUES OF 15 TO 20 PROGGED FOR ERN MS/NRN AL/CENTRAL TN 18
TO 21Z WED. RECALL THAT STP COMBINES MLCAPE..0 TO 1 KM SHEAR AND
LCL. VALUES GREATER THAN 1.0 INDICATE TORNADOES ARE POSSIBLE AND
VALUES GREATER THAN 3.0 INDICATE TORNADOES LIKELY. THESE ARE OFF
THE CHART GUYS. THE HIGHEST OBSERVED VALUES OF STP I HAVE SEEN ARE
14 FOR THE APR 2010 YAZOO CITY OUTBREAK AND 16 FOR THE MAY 10 2010
CENTRAL OK OUTBREAK. WE CAN TAKE SOME COMFORT FOR GA THAT STP IS
PROGGED TO DROP SOME BY THE TIME THE STORMS GET TO NW GA AROUND
00Z BUT...UNFORTUNATELY... WERE STILL TALKING ABOUT VALUES OF 8 TO
11 IN NORTH GA AND EVEN 6 TO 10 IN MIDDLE GEORGIA AFTER MIDNIGHT.
WE REALLY NEED TO BE PREPARED FOR THIS. MORE ON THE REST OF THE
FCST AROUND 4PM.

SNELSON

Edited by brax, 26 April 2011 - 12:14 PM.

 

[TW Archive]

SWL
Posted 26 April 2011 - 12:18 PM

brax, on 26 April 2011 - 12:12 PM, said:

FFC:

Uh. wow.

 

[TW Archive]

trency911
Posted 26 April 2011 - 12:19 PM

brax, on 26 April 2011 - 12:12 PM, said:

FFC:

Wow. Very ominous from FFC.

 

[TW Archive]

trency911
Posted 26 April 2011 - 12:21 PM

 

[TW Archive]

N2tropicAL
Posted 26 April 2011 - 12:25 PM

mwbwhorton, on 26 April 2011 - 11:02 AM, said:

Not sure ive seen 9/10 Tor con on twc since they started that....

i recall seeing a 9 in the past for alabama.....but not sure exactly when.

 

[TW Archive]

FlorenceWx
Posted 26 April 2011 - 12:26 PM

Living where I do, the combination of the FFC discussion and Dr. Tim's analysis on the 33/40 blog has me pretty spooked. Those STP values are flat scary folks. The sun's out here, current temp of 76.3, DP 67.

 

[TW Archive]

hurricaneguy
Posted 26 April 2011 - 12:30 PM

N2tropicAL, on 26 April 2011 - 12:25 PM, said:

i recall seeing a 9 in the past for alabama.....but not sure exactly when.

There was a 9 for Tuscaloosa during the Yazoo City tornado outbreak.

 

[TW Archive]

Tyler Penland
Posted 26 April 2011 - 12:32 PM

brax, on 26 April 2011 - 12:12 PM, said:

FFC:

That gives me chills... scary stuff.

 

[TW Archive]

Ghost
Posted 26 April 2011 - 12:32 PM

mwbwhorton, on 26 April 2011 - 11:51 AM, said:

Already posted see my post above...

Good grief... he was only a minute behind you

 

[TW Archive]

Stormnow
Posted 26 April 2011 - 12:33 PM

I haven't commented on this during past severe weather events. I just feel I can't hold my peace any longer.There is a particular met who I will not name that bothers me when forcasting severe wx. Today after hearing all of the news from other mets and NWS's about the threat of a major severe weather/ tornado outbreak I heard a met make a comment. " Tommorow we will be watching for STRONGER thunderstorms some which possibly could become severe". I am not an a alarmist by any means but this met often seems severe is not in his vocabulary.I certainly don't think you over hype thats dangerous because it leads to complacency if things don't pan out in marginal situations.However it is just as dangerous in my opinion to be to conservative. In situations like were currently facing I think it would be wise to be more urgent with your presentation. Certainly if your facing a system as we are. If I wasn't a weather nut I would come away from hearing this particular met thinking that its another standard marginal situation. Stay safe and God Bless. P.S This is just my opinion and nothing more.

 

[TW Archive]

South AL Wx
Posted 26 April 2011 - 12:34 PM

New Day 2 Outlook:

 

[TW Archive]

MichelleH
Posted 26 April 2011 - 12:36 PM

Stormnow, on 26 April 2011 - 12:33 PM, said:

I haven't commented on this during past severe weather events. I just feel I can't hold my peace any longer.There is a particular met who I will not name that bothers me when forcasting severe wx. Today after hearing all of the news from other mets and NWS's about the threat of a major severe weather/ tornado outbreak I heard a met make a comment. " Tommorow we will be watching for STRONGER thunderstorms some which possibly could become severe". I am not an a alarmist by any means but this met often seems severe is not in his vocabulary.I certainly don't think you over hype thats dangerous because it leads to complacency if things don't pan out in marginal situations.However it is just as dangerous in my opinion to be to conservative. In situations like were currently facing I think it would be wise to be more urgent with your presentation. Certainly if your facing a system as we are. If I wasn't a weather nut I would come away from hearing this particular met thinking that its another standard marginal situation. Stay safe and God Bless. P.S This is just my opinion and nothing more.

I know exactly how you feel! There is a met that I won't name either who I know does the very same! Could be the same one! LOL It drives me crazy because I believe he is putting people in danger.

 

[TW Archive]

Ghost
Posted 26 April 2011 - 12:37 PM

Stormnow, on 26 April 2011 - 12:33 PM, said:

I haven't commented on this during past severe weather events. I just feel I can't hold my peace any longer.There is a particular met who I will not name that bothers me when forcasting severe wx. Today after hearing all of the news from other mets and NWS's about the threat of a major severe weather/ tornado outbreak I heard a met make a comment. " Tommorow we will be watching for STRONGER thunderstorms some which possibly could become severe". I am not an a alarmist by any means but this met often seems severe is not in his vocabulary.I certainly don't think you over hype thats dangerous because it leads to complacency if things don't pan out in marginal situations.However it is just as dangerous in my opinion to be to conservative. In situations like were currently facing I think it would be wise to be more urgent with your presentation. Certainly if your facing a system as we are. If I wasn't a weather nut I would come away from hearing this particular met thinking that its another standard marginal situation. Stay safe and God Bless. P.S This is just my opinion and nothing more.

You need to name names...