DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 010516
SWODY1
SPC AC 010513

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1113 PM CST SAT JAN 31 2009

VALID 011200Z - 021200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...

POLAR BRANCH OF SPLIT FLOW REGIME WILL UNDERGO CONSIDERABLE
AMPLIFICATION THIS PERIOD AS MIDLEVEL TROUGH INTENSIFIES FROM THE
NRN PLAINS AND UPPER GREAT LAKES INTO MID MS VALLEY. FARTHER S...A
SERIES OF WEAK IMPULSES WILL BE EMBEDDED IN SUBTROPICAL BRANCH OF
WESTERLIES FROM NRN MEXICO EWD ACROSS THE GULF COAST REGION. IN THE
LOW LEVELS...COLD FRONT ATTENDANT TO POLAR BRANCH TROUGH WILL SURGE
SEWD...EXTENDING FROM THE LOWER GREAT LAKES INTO THE LOWER MS VALLEY
AND CNTRL TX BY EARLY EVENING. THIS FRONT WILL CONTINUE SEWD INTO
THE NWRN GULF OF MEXICO OVERNIGHT.

...ERN TX INTO LOWER MS VALLEY...

SRN EXTENSION OF MODEST /20-30 KT/ LLJ WILL GRADUALLY DEVELOP NEWD
AWAY FROM THE REGION TODAY IN RESPONSE TO STRONGER HEIGHT FALLS
OCCURRING OVER THE MIDWEST INTO LOWER GREAT LAKES. NONETHELESS...
PERSISTENT SLY/SWLY FLOW IN PRE-FRONTAL AIR MASS WILL SUPPORT A
GRADUAL INCREASE IN BOUNDARY LAYER MOISTURE WITH DEWPOINTS
INCREASING INTO THE LOWER/MID 50S. THIS MOISTURE WILL COMBINE WITH
MODEST MIDLEVEL LAPSE RATES AROUND 7 C/KM AND DAYTIME HEATING TO
SUPPORT A WEAKLY UNSTABLE AIR MASS WITH MLCAPE GENERALLY LESS THAN
500 J/KG.

SHOWERS AND TSTMS ARE EXPECTED TO SLOWLY INCREASE IN AREAL COVERAGE
TODAY WITHIN THE OPEN WARM SECTOR FROM SERN TX INTO PORTIONS OF
SRN/CNTRL LA AS BOUNDARY LAYER DESTABILIZES. A FEW ORGANIZED
MULTICELLS OR MARGINAL SUPERCELL STRUCTURES ARE POSSIBLE GIVEN A
KINEMATIC ENVIRONMENT CHARACTERIZED BY MODEST LOW-LEVEL HODOGRAPH
CURVATURE AND DEEP LAYER SHEAR APPROACHING 30-35 KT. THE MARGINAL
INSTABILITY IS EXPECTED TO LIMIT A MORE SUBSTANTIAL SEVERE WEATHER
THREAT...THOUGH THE MOST INTENSE STORMS WILL BE CAPABLE OF SOME
HAIL...LOCALLY STRONG WIND GUSTS AND PERHAPS A BRIEF TORNADO.

ADDITIONAL TSTMS APPEAR LIKELY ALONG COLD FRONT LATER THIS AFTERNOON
INTO EVENING FROM NERN TX INTO SRN AR/NRN LA. THIS ACTIVITY MAY
GROW UPSCALE INTO A SMALL MCS TONIGHT ALONG SEWD-MOVING COLD FRONT.
HERE TOO...THE STRONGER STORMS WILL BE CAPABLE OF SOME HAIL AND
LOCALLY STRONG WIND GUSTS.

..MEAD.. 02/01/2009

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