SWODY1
SPC AC 300457
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1057 PM CST THU JAN 29 2009
VALID 301200Z - 311200Z
...NO TSTM AREAS FORECAST...
...SYNOPSIS...
WITHIN THE MORE PROMINENT NORTHERN BRANCH OF A SPLIT UPPER FLOW
ACROSS THE EASTERN PACIFIC INTO THE WESTERN U.S....A STRONG RIDGE
NEAR THE PACIFIC COAST APPEARS LIKELY TO WEAKEN CONSIDERABLY DURING
THIS FORECAST PERIOD. MODELS INDICATE THAT THIS WILL OCCUR AS A
SIGNIFICANT SHORT WAVE IMPULSE PROGRESSES INLAND ACROSS THE BRITISH
COLUMBIA COAST AND CANADIAN ROCKIES. IN RESPONSE TO THESE
DEVELOPMENTS...AN AMPLIFIED DOWNSTREAM TROUGH IS PROGGED TO ADVANCE
FROM JUST EAST OF THE MISSISSIPPI VALLEY THROUGH ATLANTIC COASTAL
AREAS BY 12Z SATURDAY. BUT...LOW-LEVEL COLD ADVECTION IS EXPECTED
TO PERSIST AT LEAST ONE MORE DAY THROUGH MUCH OF THE GULF OF MEXICO.
WITH OBSERVATIONAL AND MODEL FORECAST DATA ALSO SUGGESTING ONLY
WEAK MOISTENING OFF THE PACIFIC WITH THE WESTERN SYSTEM...MUCH OF
THE NATION IS EXPECTED TO REMAIN DRY AND STABLY STRATIFIED... WITH
NEGLIGIBLE THUNDERSTORM POTENTIAL.
...FLORIDA...
MODELS INDICATE THAT A LEAD SURFACE COLD FRONT WILL ADVANCE THROUGH
THE REMAINDER OF THE FLORIDA PENINSULA BY LATE IN THE AFTERNOON...
WELL AHEAD OF THE ARRIVAL OF THE APPROACHING UPPER TROUGH AXIS.
THIS MAY BE ACCOMPANIED BY BOTH PRE- AND POST-FRONTAL CONVECTIVE
DEVELOPMENT ACROSS PARTS OF THE CENTRAL AND SOUTHERN PENINSULA.
BUT...WARM EQUILIBRIUM LEVELS EVIDENT IN FORECAST SOUNDINGS DO NOT
APPEAR FAVORABLE FOR SUBSTANTIAL CHARGE SEPARATION...AND THE
DEVELOPMENT OF AN APPRECIABLE RISK FOR THUNDERSTORM ACTIVITY.
..KERR.. 01/30/2009
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