SWODY2
SPC AC 311727
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1127 AM CST TUE JAN 31 2012
VALID 011200Z - 021200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
A SPLIT FLOW REGIME IS EXPECTED TO BE MAINTAINED THROUGH MUCH OF DAY
2 AS A NRN STREAM TROUGH TRACKS FROM THE GREAT LAKES THROUGH NEW
ENGLAND...AND A SRN STREAM SYSTEM...CURRENTLY MOVING INTO THE SWRN
STATES REMAINS PROGRESSIVE REACHING THE MID ATLANTIC REGION BY 12Z
THU. MODELS ARE IN AGREEMENT SHOWING THE LATTER TROUGH DEAMPLIFYING
ON WEDNESDAY AS IT MOVES INTO A CONFLUENT FLOW REGIME ACROSS THE
LOWER MS/TN VALLEYS...BUT SHOULD PHASE WITH A SECOND NRN STREAM
TROUGH ACROSS THE UPPER/MID MS VALLEY INTO THE OH VALLEY.
MEANWHILE...A LONGWAVE TROUGH IS EXPECTED TO AMPLIFY ACROSS THE WRN
STATES TO THE ROCKIES...RESULTING IN DOWNSTREAM RIDGING OVER THE
CENTRAL STATES WEDNESDAY NIGHT.
AT THE SURFACE...A COLD FRONT ATTENDANT TO THE LEAD NRN STREAM
TROUGH WILL ADVANCE THROUGH THE NERN STATES...WHILE THE OH VALLEY
SEGMENT MOVES SWD INTO THE TN VALLEY. THE WRN PART OF THIS BOUNDARY
EXTENDING WSWWD FROM AR INTO N TX AT 12Z WED SHOULD WEAKEN AS IT
MOVES SLOWLY SWD THROUGH THE LOWER MS VALLEY AND TX.
...PARTS OF E TX INTO SRN AR AND NWRN LA...
NWD MOISTURE RETURN EXPECTED THROUGH DAY 1 WILL CONTINUE AT LEAST
INTO THE EARLY PART OF DAY 2...PRIOR TO THE FORECAST OF VEERING LOW
LEVEL WINDS. SURFACE DEWPOINTS AROUND 60 F SHOULD MOVE INTO NERN TX
AND SRN AR BY LATE WED MORNING...WITH VALUES IN THE MID-UPPER 60S
CONFINED TO PRIMARILY THE TX/LA COASTS. STEEP MIDLEVEL LAPSE RATES
/7-8 C PER KM/ SPREADING EWD WITH THE SRN STREAM TROUGH AND ATOP THE
MOISTURE RETURN SHOULD SUPPORT WEAK DESTABILIZATION /MUCAPE 500-1000
J PER KG/. ALTHOUGH LAPSE RATES WILL BE MUCH WEAKER WITH SWD
EXTENT...HIGHER SURFACE DEWPOINTS/MOISTURE CONTENT SHOULD COMPENSATE
AND RESULT IN SIMILAR VALUES OF INSTABILITY TOWARD THE NWRN GULF
COAST WED AFTERNOON.
DESPITE GENERALLY WEAK BOUNDARY LAYER WINDS...STRENGTHENING MIDLEVEL
WINDS /50+ KT AT 500 MB/ ACCOMPANYING THE SRN STREAM SHORTWAVE
TROUGH WILL SUPPORT EFFECTIVE BULK SHEAR OF 40-50 KT FROM SRN AR TO
E TX...WHICH IS SUFFICIENT FOR ORGANIZED STORMS. DESPITE THIS
FACTOR AND STEEP MIDLEVEL LAPSE RATES INTO THE ARKLATEX REGION WED
AFTERNOON/EARLY EVENING...WEAK LOW LEVEL CONVERGENCE ALONG WEAKENING
SURFACE FRONT AND WEAK LOW LEVEL WAA ARE EXPECTED TO LIMIT THE
OVERALL DEVELOPMENT FOR MORE ROBUST UPDRAFTS.
MODELS DO AGREE THAT THERE IS LESS OF CHANCE FOR TSTMS AND ISOLATED
SEVERE THREAT OVER SERN OK...AND THIS AREA HAS BEEN REMOVED FROM THE
OUTLOOK. THE LOW SEVERE PROBABILITY HAS BEEN EXPANDED SWD SOME
ACROSS MORE OF E TX AND SRN AR WHERE DESPITE WEAK INSTABILITY...
SUFFICIENT BULK SHEAR MAY SUPPORT A LIMITED SEVERE WEATHER THREAT.
..PETERS.. 01/31/2012
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