Monday, December 26, 2011

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 260542
SWODY1
SPC AC 260540

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1140 PM CST SUN DEC 25 2011

VALID 261200Z - 271200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
THE PERSISTENT SOUTHERN STREAM CLOSED LOW INITIALLY OVER THE
SOUTHERN HIGH PLAINS WILL GRADUALLY OPEN/ACCELERATE EASTWARD TODAY.
AS SPLIT UPPER FLOW OVER THE CONUS STEADILY WANES...THE
AFOREMENTIONED SYSTEM IS EXPECTED TO REACH THE ARKLATEX/LOWER MS
VALLEY TONIGHT AS IT BEGINS TO COME INTO PHASE WITH A FAST MOVING
SHORTWAVE TROUGH OVER THE UPPER MIDWEST. AS A SURFACE LOW DEEPENS
AND AN INCREASINGLY MOIST AIRMASS DEVELOPS INLAND...THE PRIMARY
TSTM/SEVERE POTENTIAL FOR THE PERIOD WILL BE ACROSS THE CENTRAL GULF
COAST STATES. DRY/STABLE CONDITIONS WILL OTHERWISE PRECLUDE TSTM
POTENTIAL ACROSS THE REMAINDER OF THE CONUS.

...CENTRAL GULF COAST STATES...
AS THE PREVIOUSLY DISCUSSED UPPER SYSTEM BEGINS TO OPEN/ACCELERATE
EASTWARD OVER NORTH TX...SURFACE CYCLOGENESIS WILL GRADUALLY OCCUR
FROM THE WEST-CENTRAL GULF OF MEXICO TOWARD THE LOWER MS VALLEY/GULF
COAST STATES AND EVENTUALLY THE TN VALLEY WHILE A COLD FRONT
OTHERWISE SLOWLY ACCELERATES EASTWARD ACROSS THE REGION. A SECONDARY
SURFACE LOW WILL LIKELY BE TIED TO A MARINE WARM FRONT THAT WILL
SLOWLY NEAR THE COAST IN RESPONSE TO THE APPROACHING UPPER SYSTEM.
CURRENT EXPECTATIONS ARE FOR THIS MARINE WARM FRONT TO PRINCIPALLY
REMAIN OFFSHORE DURING THE PERIOD AS SOUTHEAST STATES
ANTICYCLONE/CONTINENTAL INFLUENCES WILL BE SLOW TO
ABATE...ESPECIALLY WITH THE POTENTIAL FOR PERSISTENT SHOWERY
CONVECTION NORTH OF THE MARINE FRONT. THAT SAID...NEAR-COASTAL
PORTIONS OF FAR SOUTHEAST LA/SOUTHERN MS COULD SEE A MARITIME
AIRMASS SPREAD INLAND TODAY AHEAD OF THE EASTWARD-ADVANCING COLD
FRONT...AND THE SAME FOR COASTAL SOUTHERN AL AND THE FL PANHANDLE
TONIGHT/EARLY TUESDAY.

WITH THE EFFECTIVE INLAND MOVEMENT OF THE MARINE FRONT SERVING AS A
DEMARCATION FOR SURFACE BASED TSTM POTENTIAL...AT LEAST SOME SEVERE
RISK WILL EXIST MAINLY TONIGHT INTO EARLY TUESDAY FOR COASTAL
PORTIONS OF MS/AL/FL PANHANDLE GIVEN THE ARRIVAL OF MORE APPRECIABLE
LARGE SCALE FORCING FOR ASCENT AND ASSOCIATED CYCLOGENESIS/POTENTIAL
MOISTENING INLAND. EVEN WHILE LAPSE RATES/BUOYANCY WILL BE MEAGER
NEAR/SOUTH OF THE MARINE FRONT...STRONG/VEERING WIND PROFILES MAY
CONTRIBUTE TO SUSTAINED STORMS/POSSIBLE SUPERCELLS. IN NEAR-COASTAL
AREAS /ROUGHLY UP TO 50-80 MILES INLAND/...THE POTENTIAL FOR A FEW
ROTATING STORMS WILL EXIST TONIGHT AHEAD OF WHAT SHOULD BE A MORE
LINEAR CONVECTIVE MODE NEAR THE EASTWARD ADVANCING COLD FRONT.
OVERALL...DAMAGING WINDS AND/OR A TORNADO MAY BE POSSIBLE...ALTHOUGH
THE SEVERE THREAT IS CURRENTLY EXPECTED TO BE ISOLATED/MARGINAL
GIVEN THE MODEST NATURE OF MOISTENING/DESTABILIZATION INLAND.

..GUYER/ROGERS.. 12/26/2011

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