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Nov 21, 2009 2000 UTC Day 1 Convective Outlook
Updated: Sat Nov 21 19:47:18 UTC 2009  (Print Version)
Probabilistic to Categorical Outlook Conversion Table (Effective Feb 14, 2006).
  | | |  
SPC Day1 2000Z Outlook Categorical SPC Day1 2000Z Outlook Categorical Legend
 Forecast Discussion
   SPC AC 211945
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0145 PM CST SAT NOV 21 2009
   
   VALID 212000Z - 221200Z
   
   ...NO SVR TSTM AREAS FORECAST...
   
   ...SERN LA...
   EARLY AFTERNOON SURFACE OBSERVATIONS/VISIBLE SATELLITE IMAGERY
   INDICATED SOME BREAKS IN THE CLOUD COVER OVER SERN LA...BOOSTING
   SURFACE TEMPERATURES.  HOWEVER...ENELY SURFACE TRAJECTORIES ARE
   MAINTAINING MODEST LOW LEVEL MOISTURE /SURFACE DEWPOINTS LOWER-MID
   50S/ OVER INLAND LOCATIONS.  SURFACE ANALYSIS SHOWED AN OCCLUDED LOW
   PRESSURE AREA HAS REMAINED OFFSHORE...THUS FAR...BUT IS EXPECTED TO
   MOVE ACROSS SERN LA THIS FORECAST PERIOD.  REGIONAL RADARS INDICATED
   A COUPLE OF STRONGER STORMS HAD FORMED SINCE THIS MORNING IN THE
   VICINITY OF THE OCCLUDED LOW...BUT WEAKENED ONCE THEY TRACKED NWD
   INTO A MORE STABLE BOUNDARY LAYER.
   
   ADDITIONAL STORMS WERE LOCATED OVER THE CENTRAL GULF WITHIN THE WARM
   SECTOR.  ALTHOUGH THE OCCLUDED LOW SHOULD MOVE OVER SERN LA...
   EXTENSIVE CLOUDS/PRECIPITATION LOCATED OVER THE NORTH CENTRAL GULF
   /ALONG AND E OF THE MS DELTA REGION/ SHOULD MAINTAIN A MORE STABLE
   AIR MASS OVER THIS AREA...AND THUS PRECLUDE THE TRIPLE POINT AND
   WARM SECTOR FROM MOVING VERY FAR NWD.  THERE ARE NO CHANGES TO THE
   SEVERE WEATHER PROBABILITIES WITH THIS OUTLOOK ISSUANCE...BUT THE
   GENERAL TSTM LINE HAS BEEN SHIFTED N/NWWD ACROSS SRN/SERN LA TO
   ACCOUNT FOR TRENDS OF ELEVATED STORMS TRACKING INLAND IN ADVANCE OF
   THE OCCLUSION.
   
   ..PETERS.. 11/21/2009
   
   .PREV DISCUSSION... /ISSUED 1003 AM CST SAT NOV 21 2009/
   
   ......SERN LA...
   AS UPPER TROUGH SHIFTS EWD FROM THE INTERMOUNTAIN WEST INTO THE
   NRN/CENTRAL ROCKIES...UPPER LOW...OVER SRN TX THIS MORNING...IS
   FORECAST TO EJECT EWD THROUGH THE LOWER MS VALLEY REGION THROUGH THE
   PERIOD. SATELLITE AND SURFACE OBSERVATIONS SHOWED A SURFACE LOW WAS
   LOCATED ABOUT 100 MI SOUTH OF LCH...WITH A WARM FRONT STRETCHING
   FROM THE LOW ESEWD TO FL KEYS. THIS SURFACE LOW IS EXPECTED TO SHIFT
   MOSTLY EWD AND MAY EVEN CROSS THE FAR SERN PORTIONS OF LA LATE THIS
   AFTERNOON/EVENING. HOWEVER...SATELLITE IMAGERY SUGGESTS THE SURFACE
   LOW HAS ALREADY BECOME OCCLUDED AS A TRAILING COLD FRONT AND
   ASSOCIATED CONVECTION APPEAR TO BE SURGING EWD FASTER THAN THE LOW
   PRESSURE SYSTEM. THIS TREND SHOULD CONTINUE AS STRONGER WINDS
   ALOFT...OVER THE CENTRAL/NRN GULF WATERS...PUSH DRIER AND COOLER AIR
   EWD AND PINCH OFF THE RICHER GULF MOISTURE...SOUTH OF THE WARM FRONT
   AND EAST OF THE COLD FRONT IN THE GULF. THEREFORE...EVEN AS THE LOW
   MOVES INLAND LATER TODAY...ANY THREAT FOR SEVERE STORMS SHOULD
   REMAIN CONFINED SOUTH AND EAST OF LA OVER THE NRN GULF WATERS.
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z

        
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