DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 140719
SWODY3
SPC AC 140717

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0217 AM CDT THU APR 14 2011

VALID 161200Z - 171200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE
MID-ATLANTIC...CAROLINAS AND ERN GA...

...MID-ATLANTIC/CAROLINAS/SE GA/NRN FL...
AN UPPER-LEVEL TROUGH WILL MOVE INTO THE OH AND TN VALLEYS SATURDAY
AS A MID-LEVEL JET NOSES INTO THE CAROLINAS. A LINE OF STRONG
THUNDERSTORMS MAY BE ONGOING SATURDAY MORNING ACROSS THE SRN
APPALACHIAN MTNS ON THE WRN EDGE OF THE LOW-LEVEL JET. AS SFC TEMPS
WARM AHEAD OF THE LINE...INTENSIFICATION SHOULD OCCUR FROM CNTRL VA
SSWWD ACROSS ECNTRL NC INTO ERN SC AND SE GA SATURDAY AFTERNOON.
FORECAST SOUNDINGS AT 21Z SATURDAY ALONG THIS CORRIDOR SHOW MLCAPE
VALUES OF 1000 TO 1500 J/KG WITH 50 TO 55 KT OF DEEP LAYER SHEAR.
THIS COMBINED WITH STRONG LOW-LEVEL SHEAR SHOULD BE SUFFICIENT FOR
ROTATING STORMS AND BOWING-LINE SEGMENTS ALONG THE LEADING EDGE OF
VERY FOCUSED LARGE-SCALE ASCENT. 40 TO 50 KT OF FLOW JUST ABOVE THE
SFC COULD FAVOR WIND DAMAGE AS THE MAIN THREAT IF A SOLID LINE MOVES
EWD ACROSS THE REGION. HOWEVER...LOW-LEVEL SHEAR WILL BE QUITE
STRONG DUE TO A WELL-DEVELOPED LOW-LEVEL JET. THIS WILL MAKE
TORNADOES A POSSIBILITY ESPECIALLY IF THE STORMS CAN REMAIN DISCRETE
OR IF THERE ARE BREAKS WITHIN THE LINE FOR ANY LENGTH OF TIME DURING
THE AFTERNOON. AN ENHANCED WIND DAMAGE THREAT OR TORNADO THREAT
COULD EXIST BUT TOO MUCH UNCERTAINTY EXISTS TO FORECAST AN ENHANCED
THREAT AREA. THE SEVERE THREAT SHOULD END DURING THE OVERNIGHT
PERIOD AS THE LINE MOVES OFF THE COAST.

FURTHER SOUTH ACROSS NRN FL...MODERATE INSTABILITY SHOULD BE IN
PLACE AHEAD OF A COLD FRONT ADVANCING SEWD ACROSS THE REGION.
ALTHOUGH CONVECTION MAY DEVELOP ALONG THE BOUNDARY AS SFC TEMPS WARM
SATURDAY...LIMITED LARGE-SCALE ASCENT WILL KEEP THE STORMS ISOLATED.
IF A STORM OR TWO CAN INITIATE...THEN A MARGINAL WIND DAMAGE OR HAIL
THREAT COULD EXIST DUE TO THE INSTABILITY AND MODERATE DEEP LAYER
SHEAR EVIDENT ON FORECAST SOUNDINGS.

..BROYLES.. 04/14/2011

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