SPC AC 121237
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0737 AM CDT SAT APR 12 2008
VALID 121300Z - 131200Z
...THERE IS A SLGT RISK OF SVR TSTMS ERN NC INTO SRN MID ATLANTIC
COAST...
...ERN CAROLINAS THROUGH MID ATLANTIC...
SSWLY LOW LEVEL JET WILL STRENGTHEN OVER THE ERN CAROLINAS WITHIN
ZONE OF HEIGHT FALLS DOWNSTREAM FROM APPROACHING UPPER TROUGH.
HOWEVER...THESE WINDS WILL MIX DOWNWARD WITH MODEST HEATING AND
ALLOW PRE-FRONTAL WINDS TO VEER TO MORE SWLY THROUGH THE DAY. AT
THE SURFACE...UPPER 50S/LOWER 60S SURFACE DEWPOINTS WILL PERSIST IN
WARM SECTOR FROM THE ERN CAROLINAS INTO ERN VA...AHEAD OF SURFACE
COLD FRONT NOW MOVING ACROSS THE APPALACHIANS. IN ADDITION...MID
LEVEL TEMPERATURES ARE FORECAST TO COOL SLIGHTLY DURING THE DAY WITH
6.5-7 C/KM 700-500 MB LAPSE RATES. AS PORTIONS OF WARM SECTOR
RECEIVE SOME HEATING...MLCAPE IS THEREFORE EXPECTED TO INCREASE TO
NEAR OR JUST ABOVE 1000 J/KG DURING THE AFTERNOON - /12Z GSO
SOUNDING SUGGESTS MLCAPE NEAR 1500 J/KG GIVEN FORECAST AFTERNOON
HIGHS NEAR 80F/.
DESPITE WEAKENING CONVERGENCE...STORMS WILL LIKELY REDEVELOP ALONG
AND AHEAD OF EWD ADVANCING COLD FRONT AS THE BOUNDARY LAYER
DESTABILIZES BY EARLY AFTERNOON. STRONG UNIDIRECTIONAL SWLY BULK
SHEAR FROM 40 TO 50 KT WILL SUPPORT STORM ORGANIZATION WITH POSSIBLE
BOWING SEGMENTS AND SUPERCELL STRUCTURES. ISOLATED DAMAGING WIND AND
HAIL WILL BE THE PRIMARY THREATS...ALTHOUGH STRONG LOW LEVEL SHEAR
MAY SUPPORT A THREAT OF A TORNADO OR TWO AS WELL...BEFORE ACTIVITY
MOVES OFFSHORE DURING THE EARLY EVENING.
...SOUTHEAST...
STRONG HEATING WITHIN MODEST GULF MOISTURE RETURN WILL LIKELY
SUSTAIN SCATTERED THUNDERSTORMS AHEAD OF SURFACE COLD FRONT EXPECTED
TO CONTINUE SEWD INTO NRN FL/COASTAL GA-SC LATER TODAY. THIS MAY
SUPPORT AN ISOLATED STRONG THUNDERSTORM TODAY. HOWEVER...WARM LAYER
AROUND 700 MB EVIDENT ON MORNING SOUNDINGS AND LIMITED LARGE SCALE
ASCENT SHOULD HINDER SEVERE THUNDERSTORM DEVELOPMENT DESPITE
STRENGTHENING SWLY MID LEVEL FLOW AND WILL MAINTAIN LOW SEVERE
PROBABILITIES ACROSS THIS REGION.
..EVANS/DIAL/CROSBIE.. 04/12/2008
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
|
