SPC AC 280532
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1232 AM CDT WED OCT 28 2009
VALID 291200Z - 301200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM TX/LA...NWD TO SRN MO...
...TX/LA...NWD TO SRN MO...
NRN PIECE OF BIFURCATING UPPER TROUGH WILL EJECT ACROSS CO INTO THE
NRN RED RIVER REGION OF NWRN MN BY THE END OF THE PERIOD WHILE A
SLOWER OPEN SHORTWAVE BEGINS TO SHIFT EWD ACROSS NM INTO FAR WEST
TX. A VERY STRONG JET CORE WILL DEVELOP ON FORWARD SIDE OF LONGWAVE
AND EXTEND FROM THE TX SOUTH PLAINS...NEWD INTO THE UPPER MS
VALLEY...DISPLACED A FEW HUNDRED MILES TO THE COOL SIDE OF FRONTAL
ZONE. EVEN SO...STRONG MID LEVEL FLOW WILL OVERSPREAD ADVANCING
COLD FRONT SUCH THAT ANY STORMS THAT MANAGE TO ROOT INTO MOISTENING
WARM SECTOR BOUNDARY LAYER WILL HAVE A PROPENSITY TO ROTATE. MODELS
CONTINUE TO SUGGEST MARITIME AIRMASS WILL INDEED RETURN ACROSS TX
LATE DAY1 INTO EARLY DAY2 WITH MID 60S SFC DEW POINTS EXPECTED AS
FAR NORTH AS CNTRL OK AHEAD OF COLD FRONT. MOISTURE PLUME WILL
GRADUALLY EXPAND AND SPREAD NWD ACROSS THE LOWER MS VALLEY AND
IMMEDIATE GULF COAST BY THE END OF THE PERIOD WITH 70+ DEW POINTS
LIKELY INTO SRN AR/MS. ALTHOUGH PRIMARY FORCING WILL SPREAD
INITIALLY TO THE NORTH OF THE CURRENT DAY2 OUTLOOK...IT APPEARS A
SQUALL LINE SHOULD DEVELOP ALONG FRONTAL ZONE AS IT INTERACTS WITH
INCREASINGLY MOIST...BUT ONLY MODESTLY UNSTABLE...ENVIRONMENT ACROSS
OK/TX. A CONSIDERABLE AMOUNT OF CONVECTION MAY ALSO TRAIL THE
LEADING WIND SHIFT AS FRONTAL ASCENT MAY BE REQUIRED FOR CONVECTIVE
INITIATION/MAINTENANCE OF LIKELY LINEAR MCS. IT/S NOT ENTIRELY
CLEAR HOW MUCH PRE-FRONTAL ACTIVITY WILL DEVELOP WITHIN STRONGLY
SHEARED AND MOIST WARM SECTOR. CURRENT THINKING IS THE MOST LIKELY
STORM MODE WILL BE A SQUALL LINE WITH EMBEDDED BOW-TYPE STRUCTURES
AND POSSIBLE SUPERCELLS. FORECAST SOUNDINGS EVEN AT 29/12Z ARE
QUITE IMPRESSIVE...SHEAR WISE...ACROSS PARTS OF NCNTRL TX INTO
SCNTRL OK...THOUGH INSTABILITY IS A BIT MEAGER. DAMAGING WINDS
APPEAR TO BE THE GREATEST RISK WITH THIS CONVECTIVE EVENT...ALONG
WITH ISOLATED TORNADOES...ESPECIALLY IF DISCRETE SUPERCELLS CAN
DEVELOP AHEAD OF MCS. ACTIVITY SHOULD PROGRESS ACROSS OK/TX INTO
THE LOWER/MID MS VALLEY DURING THE AFTERNOON/EVENING HOURS WITH
FRONTAL ZONE/MCS EXPECTED TO EXTEND FROM THE MOUTH OF THE SABINE
RIVER IN SERN TX/SWRN LA INTO WRN TN BY THE END OF THE PERIOD.
..DARROW.. 10/28/2009
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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