Friday, April 04, 2008

Slight risk in Alabama today


About to hit the road to the MSU Southeast Severe Storms Symposium. I am surprised that the SPC hasn't placed Alabama or MS under a moderate risk. Keep weather aware today. I will post when I can.
...WRN GULF COAST/LWR MS VALLEY INTO MID/SRN ATLANTIC SEABOARD...
BOUNDARY LAYER MODIFICATION MAY BEGIN TO OCCUR IN THE WAKE OF THE
RECENT COLD INTRUSION TO THE LEE OF THE CENTRAL/SOUTHERN
APPALACHIANS. BUT...THE REMNANTS OF ONGOING CONVECTION OVER THE
OHIO VALLEY ARE EXPECTED TO SPREAD AHEAD OF THE COLD FRONT AND
PROVIDE A STABILIZING INFLUENCE ACROSS THE MID ATLANTIC STATES
TODAY. MODELS ARE SUGGESTIVE THAT THE MOST SIGNIFICANT WARM SECTOR
DESTABILIZATION WILL BECOME FOCUSED ACROSS PARTS OF THE LOWER
MISSISSIPPI VALLEY/CENTRAL GULF STATES...WHERE HEATING OF A MOIST
BOUNDARY LAYER COUPLED WITH MODEST LAPSE RATES MAY YIELD CAPE IN
EXCESS OF 2000 J/KG.

INSTABILITY IS EXPECTED TO CONTRIBUTE TO VIGOROUS NEW CONVECTIVE
DEVELOPMENT...OR REINTENSIFICATION OF EARLY MORNING CONVECTIVE
ACTIVITY...SUPPORTED BY FORCING ASSOCIATED WITH THE SOUTHERN BRANCH
TROUGH...AS IT SPREADS INTO THE LOWER MISSISSIPPI VALLEY. THIS
COULD OCCUR AS EARLY AS 16-18Z...FROM PARTS OF EASTERN TEXAS INTO
NORTHERN MISSISSIPPI. AND...AS FORCING CONTINUES EASTWARD...THE
EVOLUTION OF A QUASI-LINEAR MESOSCALE CONVECTIVE SYSTEM APPEARS
POSSIBLE...PERHAPS PRECEDED BY A FEW MORE ISOLATED OR DISCRETE
STORMS.

GIVEN THE MAGNITUDE OF THE ANTICIPATED INSTABILITY...MODERATE DEEP
LAYER SHEAR...AND MOMENTUM ASSOCIATED WITH A 30-50 KT SOUTHWESTERLY
PRE-FRONTAL 850 JET...SHOULD CONTRIBUTE TO THE POTENTIAL FOR
DAMAGING WIND GUSTS...AND LARGE HAIL. AND...LOW- LEVEL SHEAR WILL
BE FAVORABLE FOR TORNADIC DEVELOPMENT... PARTICULARLY IN ANY
SUSTAINED DISCRETE STORMS.

A SEVERE THREAT IS EXPECTED TO PERSIST WITH ACTIVITY INTO EARLY
EVENING AS IT SPREADS THROUGH MUCH OF THE REMAINDER OF CENTRAL/
SOUTHERN MISSISSIPPI AND ALABAMA. BUT...THIS THREAT IS EXPECTED TO
WANE IN A MORE STABLE/STABILIZING ENVIRONMENT ACROSS THE EASTERN
GULF/SOUTH ATLANTIC COAST STATES DURING THE LATE EVENING/OVERNIGHT
HOURS.

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