SWODY1
SPC AC 131255
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0655 AM CST SUN DEC 13 2009
VALID 131300Z - 141200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
BROAD WSWLY FLOW WILL DOMINATE MUCH OF THE NATION THIS
PERIOD...BETWEEN RIDGE OVER THE SERN GULF OF MEXICO/WRN ATLANTIC AND
ELONGATED VORTEX PAIR OVER CANADA. TWO SHORTWAVE IMPULSES...ONE NOW
OVER SRN IL AND THE OTHER OVER SRN NV...WILL INFLUENCE TSTM
POTENTIAL. THE IL TROUGH SHOULD CONTINUE ENE...REACHING PA/NY THIS
EVE...WHILE THE NV DISTURBANCE CONTINUES ENE TO THE CNTRL RCKYS THIS
EVE...AND INTO THE CNTRL PLNS/LWR MO VLY BY 12Z MON.
AT THE SFC...WEAK FRONT SHOULD CONTINUE TO EDGE SLOWLY N/NE ACROSS
THE CNTRL/ERN GULF CST REGION IN RESPONSE TO IL TROUGH. THE ERN
PART OF THIS SAME BOUNDARY SHOULD REDEVELOP NW ACROSS THE SC/NC CSTL
PLN TODAY...BEFORE WEAK WAVE NOW FORMING ALONG THE BOUNDARY MOVES
OFF THE DELMARVA CST THIS EVE...TAKING THE FRONT WITH IT.
...SERN STATES...
SCTD TSTMS LIKELY WILL PERSIST ALONG AND N OF WARM/STNRY FRONT FROM
THE N CNTRL GULF OF MEXICO NEWD INTO PARTS OF AL/GA AND THE FL
PANHANDLE. SFC WINDS NEAR THE FRONT SHOULD VEER AND WEAKEN SLIGHTLY
THROUGH THE DAY...REDUCING BOTH LOW-LVL SHEAR AND CONVERGENCE. THE
RICHEST BOUNDARY LAYER MOISTURE WILL REMAIN OVER THE GULF...AND MID
LVL LAPSE RATES WILL BE WEAK. BUT DIURNAL HEATING OF AIR MASS WITH
SFC DEWPOINTS IN THE MID-UPR 60S F COULD BOOST MLCAPE TO NEAR 1000
J/KG OVER THE FL PANHANDLE...SRN AL...AND SRN GA. WHILE THIS SETUP
COULD YIELD A FEW STRONG STORMS...COMBINATION OF MODEST SHEAR AND
WEAK LAPSE RATES SUGGEST THAT SVR POTENTIAL WILL REMAIN MINIMAL.
MOST OF THE INLAND CONVECTION...MEANWHILE...SHOULD REMAIN ELEVATED
IN ZONE OF MODEST ISENTROPIC ASCENT. WHILE AN ISOLD INSTANCE OF
MARGINALLY SVR HAIL CANNOT BE RULED OUT...OVERALL HAIL THREAT WILL
BE LIMITED BY WEAK LARGE SCALE FORCING FOR ASCENT AND MODEST MID LVL
LAPSE RATES.
FARTHER NE OVER THE SC/NC CSTL PLN...SELY SFC WINDS AND MOISTENING
WILL ACCOMPANY NWWD PUSH OF SFC FRONT THIS AFTN. BUT REGION WILL
REMAIN OVERCAST...AND WARM LAYER AROUND 700 MB WILL CONTRIBUTE TO
CONSIDERABLE SFC-BASED CIN...LESSENING CHANCES FOR SFC-BASED STORMS.
SVR POTENTIAL THUS APPEARS TOO LOW/CONDITIONAL TO WARRANT
INTRODUCTION OF SVR PROBABILITIES ATTM.
...GRT BASIN...
SPORADIC/ISOLD LIGHTNING STRIKES MAY OCCUR THROUGH EARLY EVE WITH
LOW/MID LVL CONVECTION AHEAD OF NV UPR TROUGH...BUT POTENTIAL
APPEARS TOO LIMITED FOR A CATEGORICAL GEN TSTM AREA.
..CORFIDI.. 12/13/2009
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