SWODY1
SPC AC 170538
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1238 AM CDT SAT OCT 17 2009
VALID 171200Z - 181200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
LARGE SCALE PATTERN WILL NOT PROVE PARTICULARLY FAVORABLE FOR DEEP
CONVECTION CAPABLE OF GENERATING LIGHTNING...MUCH LESS ORGANIZED
SEVERE THUNDERSTORMS DURING THE UPCOMING DAY1 PERIOD OVER THE CONUS.
LATEST MODEL GUIDANCE DOES HOWEVER SUGGEST TWO AREAS WHERE ISOLATED
THUNDERSTORMS MAY DEVELOP...PRIMARILY EXTREME SOUTH FL AND PARTS OF
THE PACIFIC NW. IN BOTH OF THESE AREAS THE GREATEST THREAT FOR
CONVECTION WILL OCCUR WITHIN WARM SECTOR IMMEDIATELY AHEAD OF A COLD
FRONT.
...PACIFIC NW...
EARLY MORNING WV IMAGERY CLEARLY DEPICTS A WELL DEFINED UPPER
VORT/SHORT WAVE TROUGH...ROUGHLY 500 MI OFF THE WA/ORE
COAST...SHIFTING ENEWD TOWARD THE PACIFIC NW. MATURE BAROCLINIC
LEAF PRECEDES THE TROUGH...AND ISOLATED THUNDERSTORMS HAVE OCCURRED
AT TIMES WITHIN THE ASSOCIATED WARM CONVEYOR. IT APPEARS THIS WILL
BE THE PRIMARY FORCING MECHANISM FOR POTENTIAL THUNDERSTORM
DEVELOPMENT AS FORECAST SOUNDINGS SUGGEST SUFFICIENT ELEVATED
BUOYANCY FOR POSSIBLE LIGHTNING DISCHARGE WITHIN THIS MOIST PLUME
AHEAD OF WIND SHIFT. CONVECTIVE THREAT WILL INCREASE AS WARM
CONVEYOR SHIFTS INLAND LATER TODAY. EVEN SO ACTIVITY IS NOT
EXPECTED TO ATTAIN LEVELS OF INTENSITY THAT WOULD WARRANT SEVERE
PROBABILITIES.
...SOUTH FL...
WIND SHIFT CONTINUES TO SURGE SWD ACROSS THE FL PENINSULA...WITH PRE
FRONTAL SFC FLOW EXPECTED TO BEGIN TO VEER AHEAD OF COLD FRONT
ACROSS THE EVERGLADES BY SUNRISE. ALTHOUGH THE PRIMARY THREAT FOR
DEEP CONVECTION WILL REMAIN OFFSHORE...IT APPEARS ISOLATED
THUNDERSTORMS COULD DEVELOP DURING THE FIRST HALF OF THE PERIOD
BEFORE COLD FRONT SWEEPS SOUTH OF THE PENINSULA.
..DARROW/GRAMS.. 10/17/2009
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