SWODY2
SPC AC 071721
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1121 AM CST MON NOV 07 2011
VALID 081200Z - 091200Z
...THERE IS A SLGT RISK OF SVR TSTMS MID MS RIVER VALLEY INTO THE
ARKLATEX...
A POTENT UPPER TROUGH WILL MOVE FROM THE SRN HIGH PLAINS AT THE
START OF THE PERIOD TO THE MID MS RIVER VALLEY BY DAYBREAK
WEDNESDAY. A SURFACE LOW OVER NRN OK WILL MIGRATE NEWD TO NEAR SRN
LAKE MICH ALONG A BAROCLINIC ZONE EXTENDING FROM THE SRN PLAINS INTO
THE GREAT LAKES. AS THE UPPER TROUGH LIFTS AWAY FROM THE SRN PLAINS
STATES...A COLD FRONT WILL ACCELERATE EWD ACROSS ERN OK AND NERN TX
DURING THE AFTERNOON. STRONG TROPOSPHERIC SHEAR AND FORCING FOR
ASCENT WILL COMBINE WITH A SLY FETCH OF INCREASING MOIST/UNSTABLE
AIRMASS FROM THE WRN GULF AND SUPPORT SCATTERED TO NUMEROUS
THUNDERSTORMS /SOME SEVERE/ AS THE FRONT PUSHES EWD.
...OZARKS SWD INTO ERN TX...
A BAND OF MARGINALLY SEVERE STORMS ONGOING ACROSS OK/KS DURING THE
MORNING WILL WEAKEN INTO A BROKEN BAND OF STORMS BEFORE
REINVIGORATING BY AFTERNOON AS THE BOUNDARY LAYER DESTABILIZES AHEAD
OF THE CONVECTION/COLD FRONT. HERE...UPWARDS OF 500-1000 J/KG
MLCAPE AND 50 KTS DEEP LAYER SHEAR AHEAD OF THE ADVANCING SQUALL
LINE WILL FAVOR PRIMARILY WIND DAMAGE WITH ISOLD EMBEDDED ROTATING
UPDRAFTS POSSIBLE AS WELL. SEVERE COVERAGE IS EXPECTED TO DIMINISH
WITH SWD EXTENT...NAMELY ACROSS ERN TX AND THE LOWER SABINE RIVER
VALLEY AS THE STRONGEST FORCING FOR ASCENT LIFTS AWAY FROM THE
REGION INTO THE MIDWEST. DESPITE DECREASING BACKGROUND LARGE SCALE
SUPPORT AND MODEST LAPSE RATES...A MOIST BOUNDARY LAYER
CHARACTERIZED BY DEWPOINTS WELL INTO THE 60S...STRONG MID-HIGH LEVEL
FLOW...AND SUFFICIENT LOW LEVEL CONVERGENCE ALONG THE FRONT WILL
SEEMINGLY CONTRIBUTE TO ISOLD SEVERE INTO ERN TX.
...MID MS RIVER VALLEY...
ONGOING ELEVATED STORMS DUE TO A STRONG WARM CONVEYOR ON THE NOSE OF
A 50 KT LLJ AT 12Z TUE WILL WANE AND SPREAD NWD WITH A LULL IN STORM
ACTIVITY EXPECTED DURING THE LATE MORNING/EARLY AFTERNOON HOURS.
STRONG MASS TRANSPORT INTO THE REGION COINCIDENT WITH DIURNAL
DESTABILIZATION WILL PROBABLY LEAD TO WEAK SURFACE-BASED BUOYANCY BY
MID AFTERNOON ALONG AND AHEAD OF THE SURFACE LOW AS IT DEVELOPS NEWD
INTO N-CNTRL MO BY WED. EVENING. MODEL FORECAST SOUNDINGS VARY
REGARDING THE DEGREE OF DESTABILIZATION BUT GENERALLY SHOW A FEW
HUNDRED J/KG SBCAPE WITH A WIND PROFILE STRONGLY SUPPORTIVE OF
ORGANIZED STORMS. WIND DAMAGE APPEARS TO BE THE MAIN
THREAT...ALTHOUGH AN ISOLD TORNADO RISK MAY DEVELOP NEAR AND SE OF
THE SURFACE LOW--CONTINGENT UPON AIRMASS DESTABILIZATION. AFTER
SUNSET...MEAGER POTENTIAL INSTABILITY WITHIN A LLJ EXIT REGION WILL
LIKELY MAINTAIN AN EWD MOVING FORCED SQUALL LINE.
..SMITH/DARROW.. 11/07/2011
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