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4/4/11 Deep South Outbreak
03-31-2011, 06:49 AM
Post: #1
4/4/11 Deep South Outbreak
Lot of talk about next weeks possible biggest outbreak in years


Quote:Day 4-8 Convective Outlook Issued on Mar 31, 2011
Updated: Thu Mar 31 09:10:03 UTC 2011
[Image: day48prob.gif]
D4Sun, Apr 03, 2011 - Mon, Apr 04, 2011 D7Wed, Apr 06, 2011 - Thu, Apr 07, 2011
D5Mon, Apr 04, 2011 - Tue, Apr 05, 2011 D8Thu, Apr 07, 2011 - Fri, Apr 08, 2011
D6Tue, Apr 05, 2011 - Wed, Apr 06, 2011 (All days are valid from 12 UTC - 12 UTC)
Note: A severe weather area depicted in the Day 4-8 period indicates a 30% or higher probability for severe thunderstorms within 25 miles of any point.

PREDICTABILITY TOO LOW is used to indicate severe storms may be possible based on some model scenarios. However, the location or occurrence of severe storms are in doubt due to: 1) large differences in the deterministic model solutions, 2) large spread in the ensemble guidance, and/or 3) minimal run-to-run continuity.
POTENTIAL TOO LOW means the threat for a regional area of organized severe storms appears highly unlikely during the entire period (e.g. less than a 30% probability for a regional severe storm area across the CONUS through the entire Day 4-8 period).

Forecast Discussion
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 310909
SPC AC 310909

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0409 AM CDT THU MAR 31 2011

VALID 031200Z - 081200Z

...DISCUSSION...

SOME TIMING AND AMPLITUDE DIFFERENCES PERSIST AMONG GFS...ECMWF AND
ENSEMBLE MEMBERS. HOWEVER...MODELS HAVE GENERALLY CONVERGED TOWARD A
SIMILAR SOLUTION REGARDING UPPER TROUGH FORECAST TO AMPLIFY AND MOVE
INTO THE PLAINS LATE DAY 4...THEN MS/OH VALLEYS AND SERN STATES DAY
5 AND FINALLY ATLANTIC COASTAL REGION DAY 6. IT APPEARS THIS FEATURE
WILL REMAIN A PROGRESSIVE UPPER WAVE AS IT ADVANCES THROUGH THE ERN
2/3 OF THE COUNTRY.

...DAY 4...

LLJ ASSOCIATED WITH CNTRL PLAINS LEE CYCLONE WILL CONTINUE ADVECTING
RICHER GULF MOISTURE THROUGH WARM SECTOR ACROSS THE SRN-CNTRL PLAINS
AND LOWER-MID MS VALLEY. EML WILL EXPAND EWD AND EFFECTIVELY CAP
WARM SECTOR EAST OF DRYLINE OVER THE PLAINS. HOWEVER...POTENTIAL
WILL EXIST FOR IMPULSE TO EJECT EWD AHEAD OF MAIN UPPER TROUGH.
DIABATIC WARMING OF THE BOUNDARY LAYER AND DRYLINE CONVERGENCE MIGHT
BECOME SUFFICIENT FOR ISOLATED SUPERCELLS FROM KS SWD INTO OK AND
NRN TX. ADDITIONAL STORMS WILL BE MORE LIKELY AS THE COLD FRONT
ADVANCES SEWD AND INTERCEPTS THE DRYLINE FROM THE CNTRL PLAINS INTO
THE MID MS VALLEY AREA.

...DAY 5...

WIDESPREAD SEVERE STORMS ARE BECOMING INCREASINGLY PROBABLE DAY 5.
GULF MOISTURE WILL ADVECT NWD THROUGH LOWER-MID MS VALLEY...SERN
STATES AND OH VALLEY IN ASSOCIATION WITH VERY STRONG EWD MIGRATING
LLJ. MORE WIDESPREAD THUNDERSTORM DEVELOPMENT WILL BECOME PROBABLE
AS FORCING FOR DEEP ASCENT ATTENDING THE UPPER TROUGH SHIFTS EAST OF
STRONGER EML. THREAT WILL EXIST FOR SUPERCELLS AND LINE SEGMENTS
WITH TORNADOES...LARGE HAIL AND DAMAGING WIND.

...DAY 6...

SEVERE THREAT SHOULD CONTINUE THROUGH THE REMAINDER OF THE SERN
STATES AND THE MID ATLANTIC SEABOARD.

..DIAL.. 03/31/2011

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03-31-2011, 07:29 AM
Post: #2
4/4/11 Deep South Outbreak
....

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03-31-2011, 08:56 AM
Post: #3
4/4/11 Deep South Outbreak
[Image: image3.gif]

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03-31-2011, 09:04 AM
Post: #4
4/4/11 Deep South Outbreak
So will we see the DOW w/Josh or the TIV2 or the Dominator 1 & 2 in the deep south?

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03-31-2011, 09:37 AM
Post: #5
4/4/11 Deep South Outbreak
Joe-Nathan Wrote:So will we see the DOE w/Josh or the TIV2 or the Dominator 1 & 2 in the deep south?

TIV and Sean Casey will be in Atlanta Sunday showing the IMAX film ..... Does that count ?

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03-31-2011, 11:01 AM
Post: #6
4/4/11 Deep South Outbreak
ROLLTIDE Wrote:TIV and Sean Casey will be in Atlanta Sunday showing the IMAX film ..... Does that count ?

I wonder how many times the TIV broke down along the trip.

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03-31-2011, 11:34 AM
Post: #7
4/4/11 Deep South Outbreak
From NWSChat: In coordination with the Florida State Watch Office - approximately 70 people are trapped in a collapsed building at the Sun n Fun aviation fair from the severe winds associated with the storm that recently impacted the area.

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03-31-2011, 11:52 AM
Post: #8
4/4/11 Deep South Outbreak
WTSP-TV (Tampa, FL) is streaming LIVE following the passage of severe storms http://goo.gl/kwI0U

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03-31-2011, 05:28 PM
Post: #9
4/4/11 Deep South Outbreak
James Spann

Quote:SEVERE WEATHER THREAT EARLY NEXT WEEK: No doubt much of the Deep South will have a significant severe weather threat, but no way of nailing down the details this early. The 12Z GFS is slower, suggesting the main threat will come Tuesday, perhaps during the afternoon and evening hours when the air is most unstable. However, the 12Z ECMWF is faster, with the main batch of rain and storms in here Monday night. Gut feeling says the slower GFS is correct, but again it is simply too early to get the timing down. We will be able to be much more specific over the weekend.

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04-01-2011, 05:51 AM
Post: #10
4/4/11 Deep South Outbreak
....

Quote:Day 4-8 Convective Outlook Issued on Apr 1, 2011
Updated: Fri Apr 1 08:58:02 UTC 2011
[Image: day48prob.gif]
D4Mon, Apr 04, 2011 - Tue, Apr 05, 2011 D7Thu, Apr 07, 2011 - Fri, Apr 08, 2011
D5Tue, Apr 05, 2011 - Wed, Apr 06, 2011 D8Fri, Apr 08, 2011 - Sat, Apr 09, 2011
D6Wed, Apr 06, 2011 - Thu, Apr 07, 2011 (All days are valid from 12 UTC - 12 UTC)
Note: A severe weather area depicted in the Day 4-8 period indicates a 30% or higher probability for severe thunderstorms within 25 miles of any point.

PREDICTABILITY TOO LOW is used to indicate severe storms may be possible based on some model scenarios. However, the location or occurrence of severe storms are in doubt due to: 1) large differences in the deterministic model solutions, 2) large spread in the ensemble guidance, and/or 3) minimal run-to-run continuity.
POTENTIAL TOO LOW means the threat for a regional area of organized severe storms appears highly unlikely during the entire period (e.g. less than a 30% probability for a regional severe storm area across the CONUS through the entire Day 4-8 period).

Forecast Discussion
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 010857
SPC AC 010857

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0357 AM CDT FRI APR 01 2011

VALID 041200Z - 091200Z

...DISCUSSION...
00Z GFS/ECMWF REMAIN SIMILAR IN MAINTAINING AN AMPLIFIED FULL
LATITUDE TROUGH MOVING EWD ACROSS THE PLAINS AND MS/LOWER OH VALLEYS
ON DAY 4 /MON/...AND THEN ACROSS THE ERN STATES ON DAY 5 /TUE/ AS A
MORE NEGATIVELY-TILTED SYSTEM. THESE MODELS DO DIFFER IN THE TIMING
OF THIS TROUGH WITH THE ECMWF FASTER...ESPECIALLY ON DAY 5
ACCELERATING THIS TROUGH OFF THE ERN SEABOARD BY 12Z WEDNESDAY.

...DAY 4 /MON APR 4/...
MODELS MAINTAIN LIKELIHOOD FOR WIDESPREAD SEVERE STORMS FROM THE
MID-LOWER MS VALLEY INTO THE OH/TN VALLEYS AND CENTRAL GULF COAST
STATES ON DAY 4. GULF MOISTURE WILL ADVECT NWD ACROSS THIS REGION
IN ASSOCIATION WITH VERY STRONG EWD MIGRATING SLY LLJ. TSTM
ACTIVITY WILL BE SUPPORTED AS FORCING FOR DEEP ASCENT ATTENDING THE
UPPER TROUGH SHIFTS EAST OF STRONGER EML. THIS AND STRONG WIND
FIELDS WILL SUPPORT A THREAT FOR SUPERCELLS AND LINE SEGMENTS
WITH TORNADOES...LARGE HAIL AND DAMAGING WINDS.

...DAY 5 /TUE APR 5/...
DESPITE THE TIMING DIFFERENCES OF THE GFS/ECMWF...A SEVERE THREAT
SHOULD CONTINUE THROUGH THE REMAINDER OF THE SERN STATES AND THE MID
ATLANTIC SEABOARD ON TUESDAY.

..PETERS.. 04/01/2011


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