SWODY2
SPC AC 210700
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CST THU FEB 21 2008
VALID 221200Z - 231200Z
..THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE GULF
COASTAL STATES INTO NRN FL...
..SYNOPSIS...
OVERALL CONSENSUS IS THAT SWRN U.S. SHORTWAVE TROUGH WILL EJECT
ENEWD INTO THE TN AND OH VALLEYS...SHEAR NEWD AND DEAMPLIFY AS IT
TRIES TO PHASE WITH NRN STREAM UPPER TROUGH. A STRONG 80 KT MID
LEVEL JET WILL ROTATE THROUGH THE SRN PERIPHERY OF THIS FEATURE.
WEAK SURFACE LOW EXPECTED TO BE NEAR THE TN VALLEY EARLY FRIDAY WILL
DEVELOP NEWD INTO THE OH VALLEY...WHILE SECONDARY WEAK CYCLOGENESIS
COMMENCES ALONG BAROCLINIC ZONE OFF THE NC COAST. AS THE INITIAL
SURFACE LOW LIFTS NEWD...A COLD FRONT WILL SHIFT SEWD THROUGH THE
SERN U.S. AND LIKELY EXTEND FROM NEAR THE CAROLINA COASTAL REGIONS
SWWD THROUGH THE FL PANHANDLE BY THE END OF THIS PERIOD. COASTAL
BOUNDARY WILL LIKELY LIFT INLAND INTO THE SRN PORTIONS OF THE GULF
COASTAL STATES.
..SRN PORTIONS OF THE GULF COASTAL STATES THROUGH NRN FL...
NWD ADVANCE OF MOIST WARM SECTOR MAY BE SOMEWHAT LIMITED BY THE COOL
AIR IN PLACE LEFTOVER FROM RETREATING OH VALLEY SURFACE RIDGE AND
TENDENCY FOR THE LOW LEVEL JET TO VEER AND SHIFT EWD WITH TIME.
CURRENT THINKING IS THAT MID TO UPPER 60S DEWPOINTS WILL ADVANCE
INTO THE SRN PARTS OF THE GULF COASTAL STATES. WSWLY MID LEVEL FLOW
MAY ADVECT STEEPER 6-6.5 C/KM MID LEVEL LAPSE RATES OVER A PORTION
OF THE WARM SECTOR WITH TIME...AND THIS WILL CONTRIBUTE TO
DESTABILIZATION. HOWEVER...POTENTIAL FOR WIDESPREAD CLOUDS MAY LIMIT
OVERALL MAGNITUDE OF INSTABILITY TO AOB 1200 J/KG. SCATTERED STORMS
WILL LIKELY BE ONGOING EARLY FRIDAY FROM THE MS VALLEY NEWD INTO THE
TN VALLEY. ACTIVITY OVER THE TN VALLEY WILL BE ELEVATED.
HOWEVER...ANY STORMS FARTHER SW OVER SRN PARTS OF THE LOWER MS
VALLEY MAY BE CLOSE ENOUGH TO SURFACE BASED TO SUPPORT AN ONGOING
SEVERE THREAT. THE LOW LEVEL JET IS FORECAST TO VEER AND SHIFT EWD
DURING THE DAY AS THE UPPER TROUGH SHEARS ENEWD.
ADDITIONAL STORMS MAY DEVELOP IN WARM SECTOR OVER SRN PARTS OF THE
GULF COASTAL STATES WITHIN THE LOW LEVEL CONFLUENT REGIME ALONG THE
WARM CONVEYOR BELT AS THE BOUNDARY LAYER DESTABILIZES. THE STRONG 80
KT MID LEVEL JET WILL CONTRIBUTE TO DEEP SHEAR OF 60+ KT.
HOWEVER...TENDENCY FOR THE LOW LEVEL JET TO VEER WITH TIME SUGGESTS
WIND PROFILES IN WARM SECTOR WILL BECOME LARGELY UNIDIRECTIONAL.
STORMS MAY EVOLVE INTO SUPERCELLS AND BOWING SEGMENTS WITH DAMAGING
WIND EXPECTED THE MAIN THREAT...THOUGH HAIL MAY ALSO BE POSSIBLE
DEPENDING ON MID LEVEL LAPSE RATES AND DEGREE OF DESTABILIZATION.
ANY TORNADO THREAT APPEARS CONDITIONAL UPON HOW QUICKLY THE LOW
LEVEL JET VEERS AND SHIFTS EWD AWAY FROM THE DESTABILIZING WARM
SECTOR.
.DIAL.. 02/21/2008
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