SWODY1
SPC AC 181257
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0657 AM CST TUE DEC 18 2007
VALID 181300Z - 191200Z
..NO TSTM AREAS FORECAST...
..SYNOPSIS...
A PROGRESSIVE ZONAL REGIME WILL CONTINUE OVER THE CONUS INTO EARLY
WEDNESDAY. ONE SHORTWAVE TROUGH WILL MOVE INLAND OVER ORE/CA AND
THE GREAT BASIN DURING THE PERIOD...WHILE ANOTHER LOW AMPLITUDE WAVE
/WITH EMBEDDED VORTICITY CENTERS OVER MN AND ALONG THE KS/OK BORDER/
MOVES EWD TO THE GREAT LAKES AND APPALACHIANS.
THE PAC COAST SYSTEM WILL BE ACCOMPANIED BY RELATIVELY COLD MID
LEVEL TEMPERATURES /-25 C AT 500 MB/ AND 6.5-7 C/KM LAPSE RATES FROM
THE SURFACE TO ABOUT 500 MB. HOWEVER...BUOYANCY WILL BE QUITE
LIMITED /MUCAPE VALUES AOB 100 J/KG/...VERY FEW LIGHTNING STRIKES
HAVE BEEN NOTED IN OCEANIC DATA...AND ANY THUNDERSTORM THREAT SHOULD
REMAIN TOO MARGINAL FOR AN OUTLOOK AREA.
THE KS/OK PORTION OF THE PLAINS MID LEVEL TROUGH IS ACCOMPANIED BY A
WEAK CYCLONE NEAR P28. THIS SYSTEM WILL WEAKEN GRADUALLY DURING THE
DAY WHILE PROGRESSING WELL E OF THE ROCKIES...BUT A MODIFYING CP AIR
MASS WILL CONTINUE TO SPREAD NWD/NEWD TO THE NW GULF COAST ON
INDUCED SLY LOW-LEVEL FLOW. OBSERVED LOWER 60 BOUNDARY LAYER
DEWPOINTS ACROSS THE WRN GULF MAY CONTRIBUTE TO WEAK INSTABILITY
ACROSS SE TX AND SRN LA LATER TODAY INTO TONIGHT. STILL...THE
MAGNITUDE OF THE INSTABILITY WILL BE WEAK IN AN ENVIRONMENT WITH
LITTLE ORGANIZED FORCING FOR ASCENT...THUS THUNDERSTORMS ARE NOT
EXPECTED.
.THOMPSON.. 12/18/2007
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