SWODY1
SPC AC 021243
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0643 AM CST WED DEC 02 2009
VALID 021300Z - 031200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF SRN AL/NRN FL
INTO THE CAROLINAS/SERN VA...
...NERN GULF COAST INTO THE CAROLINAS/SERN VA...
BOUNDARY LAYER MOISTURE RETURN OUT OF THE ERN GOM AND OFF THE
ATLANTIC AHEAD OF INTENSE MID/UPPER LEVEL SHORTWAVE TROUGH EJECTING
NEWD ACROSS THE DEEP SOUTH WILL REMAIN PRIMARY FOCUS FOR SEVERE TSTM
FORECAST. THIS AREA WILL BE OVERSPREAD BY A BROAD AREA OF ENHANCED
WIND FIELDS AHEAD OF COMPACT SYSTEM. IF SUFFICIENT
MOISTENING/HEATING CAN DEVELOP WITHIN MODEST WARM SECTOR EVOLVING
FROM NWRN FL/SRN GA INTO THE ERN CAROLINAS...THEN ENVIRONMENT WILL
BECOME VERY FAVORABLE FOR TORNADIC SUPERCELLS AND LEWP STRUCTURES
WITHIN A BROKEN SQUALL LINE FORECAST TO ADVANCE ENEWD ACROSS THE
REGION. PERSISTENT QUESTIONS ABOUT INSTABILITY PRECLUDES MDT RISK
ATTM...BUT OUTLOOK COULD BE UPGRADED LATER TODAY.
12Z SURFACE ANALYSIS INDICATED LARGE AREA OF COOL/STABLE CONTINENTAL
AIR REMAINED ACROSS THE MID ATLANTIC/CAROLINAS INTO CENTRAL/NRN
GA...WITH MARINE/WARM FRONTS EXTENDING JUST OFF THE FL PANHANDLE AND
ERN CAROLINAS. STRONG PRESSURE FALLS SHOULD CONTINUE TO SUPPORT NWD
RECOVERY OF 60+F SFC DEW POINTS INTO MORE CENTRAL-SRN GA AND THE FL
PENINSULA...WITH GRADUAL INLAND RECOVERY OFF THE ATLANTIC EXPECTED
INTO ERN AND PART OF THE CENTRAL CAROLINAS. BROKEN SQUALL LINE
ALREADY DEVELOPING OVER FAR SWRN AL/WRN FL PANHANDLE AT DAYBREAK
WILL LIKELY CONTINUE ADVANCING ENEWD ACROSS SRN GA/NRN FL...AND
EVENTUALLY BUILD SEWD INTO CENTRAL FL THIS AFTERNOON. DEPENDING ON
QUALITY OF PRECEDING INSTABILITY...POTENTIAL FOR DAMAGING WINDS AND
TORNADOES WILL LIKEWISE INCREASE BOTH WITH THE LINE AND WITH ANY
PRECEDING DISCRETE DEVELOPMENT. ATTM...MODEL FORECAST SOUNDINGS
INDICATE THREAT WILL RAMP-UP BY THE MID MORNING WITH ANY ENSUING
TORNADO POTENTIALLY BECOMING QUITE STRONG/DAMAGING GIVEN SFC-1 KM
SRH IN EXCESS OF 350 M2/S2 AND SFC-6 KM BULK SHEAR GREATER THAN 50
KT. NWD EXTENT OF SEVERE THREAT WITH THIS ACTIVITY WILL BE MORE
PROBLEMATIC BUT AT LEAST AN ISOLATED DAMAGING WIND THREAT WILL
LIKELY DEVELOP INTO THE SRN APPALACHIANS THROUGH THE DAY.
THREAT SHOULD INCREASE DURING THE MID TO LATE AFTERNOON INTO PARTS
OF ERN GA/SC AS MARINE AIR ADVANCES INLAND FROM INCREASING SSELY LOW
LEVEL WINDS...DESPITE PERSISTENT MOIST CONVECTION THROUGH THE
MORNING. THIS AREA MAY EVOLVE SEPARATELY OR ALONG NRN FRINGE OF
BROKEN SQUALL LINE ADVANCING ACROSS SRN GA/NRN FL...BUT SHOULD ALSO
ADVANCE QUICKLY NEWD IN THE FORM OF FAST MOVING LINES AND/OR
SUPERCELLS ACROSS PARTS OF THE CAROLINAS AND SERN VA. GIVEN EXTREME
WIND FIELDS...WIND DAMAGE AND TORNADO THREAT IS EXPECTED TO INCREASE
LATE TODAY/THIS EVENING BEFORE ACTIVITY MOVES OFFSHORE LATER THIS
EVENING/TONIGHT. SHOULD AIR MASS RECOVER AS FORECAST...THE
POTENTIAL FOR A SIGNIFICANT TORNADO OR TWO WILL ALSO EXIST ACROSS
THIS REGION.
...NRN AL TO ERN KY...
ALTHOUGH MOISTURE RETURN WILL BE MUCH LESS THAN FARTHER S...WITH
SURFACE DEWPOINTS INTO THE UPPER 40S POSSIBLE...STEEPER MID LEVEL
LAPSE RATES ACCOMPANYING THE SHORTWAVE TROUGH SHOULD RESULT IN
WEAK...ELEVATED INSTABILITY. THIS COMBINED WITH EFFECTIVE BULK
SHEAR OF 25-30 KT SUGGESTS A FEW ELEVATED STORMS MAY BE CAPABLE OF
HAIL.
..EVANS.. 12/02/2009
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