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Dec 18, 2014 0700 UTC Day 2 Convective Outlook
Updated: Thu Dec 18 06:00:03 UTC 2014 (Print Version | 20141218 0700Z Day 2 shapefile | 20141218 0700Z Day 2 KML)
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 Forecast Discussion

   SPC AC 180600

   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1200 AM CST THU DEC 18 2014

   VALID 191200Z - 201200Z

   ...THERE IS A MRGL RISK OF SVR TSTMS FRIDAY ACROSS PARTS OF THE
   MIDDLE AND UPPER TEXAS COAST THROUGH THE CENTRAL GULF COAST...

   ...SUMMARY...
   STRONG THUNDERSTORMS ARE POSSIBLE FRIDAY ACROSS PARTS OF MID AND
   UPPER TEXAS COASTAL AREAS INTO THE VICINITY OF THE LOUISIANA COAST.

   ...SYNOPSIS...
   SOME AMPLIFICATION OF INITIALLY STRONG ZONAL FLOW ACROSS THE
   MID-LATITUDE PACIFIC APPEARS POSSIBLE AS EARLY AS THIS FORECAST
   PERIOD.  BUT THIS IS NOT YET EXPECTED TO IMPACT THE PATTERN MUCH
   ACROSS NORTH AMERICA...WITH LITTLE CHANGE FROM THURSDAY THROUGH
   FRIDAY.  SHORT WAVES WITHIN SPLIT WESTERLIES EMERGING FROM THE
   PACIFIC SHOULD REMAIN PROGRESSIVE...INCLUDING ONE FORECAST TO
   ACCELERATE EAST NORTHEAST OF THE TEXAS BIG BEND...THROUGH PORTIONS
   OF THE LOWER MISSISSIPPI VALLEY BY 12Z SATURDAY.

   FORCING ASSOCIATED WITH THIS IMPULSE PROBABLY WILL SUPPORT A
   DEVELOPING WAVE ALONG A REMNANT FRONTAL ZONE...EXTENDING ACROSS THE
   NORTHERN GULF OF MEXICO AND MIDDLE TEXAS COAST INTO THE LOWER RIO
   GRANDE VALLEY.  HOWEVER...DRY/POTENTIALLY COLD BOUNDARY LAYER AIR
   INITIALLY PRESENT ACROSS MUCH OF THE GULF COAST STATES...TO THE
   NORTH OF THE FRONT...AS WELL AS ACROSS THE NORTHEASTERN GULF OF
   MEXICO...MAY BE SLOW TO MODIFY.  AND IT APPEARS INCREASINGLY
   PROBABLE THAT STRONGER FORCING FOR LARGE-SCALE ASCENT WILL SHIFT
   NORTHEASTWARD...AWAY FROM THE SURFACE FRONT...EARLY IN THE PERIOD. 
   MODELS SEEM TO BE TRENDING TOWARD AN EVEN MORE SUPPRESSED/WEAKER
   FRONTAL WAVE...TRACKING NEAR OR JUST SOUTH OF COASTAL AREAS...AFTER
   MIGRATING EAST OF THE TEXAS COAST.

   ...MID/UPPER TEXAS COAST THROUGH CENTRAL GULF COASTAL AREAS...
   GIVEN THE STILL FAIRLY MODEST NATURE OF THE BOUNDARY LAYER RECOVERY
   OVER THE WESTERN GULF...ANY BOUNDARY LAYER DESTABILIZATION LIKELY
   WILL REMAIN RATHER WEAK...WITH LITTLE APPRECIABLE STEEPENING OF
   MID-LEVEL LAPSE RATES FORECAST ACROSS MUCH OF THE REGION.  WHILE 5
   PERCENT SEVERE PROBABILITIES ARE BEING MAINTAINED...THEY ARE NOW
   CONFINED TO MORE IMMEDIATE COASTAL AREAS TO ACCOUNT FOR THE LATEST
   MODEL TRENDS CONCERNING THE SURFACE LOW...AND POTENTIAL FOR THE WARM
   SECTOR TO ADVANCE INLAND.  WITH CURRENT TRENDS ALSO SUGGESTING
   CORRESPONDING WEAKER LOW-LEVEL WIND FIELDS AND SHEAR WITHIN THE WARM
   SECTOR...IT IS BECOMING MORE UNCLEAR JUST HOW CONDUCIVE THE
   ENVIRONMENT WILL BE TO SEVERE WEATHER POTENTIAL.  IF CURRENT TRENDS
   PERSIST...SEVERE PROBABILITIES COULD BE REMOVED IN LATER OUTLOOKS
   FOR THIS PERIOD.

   ...PACIFIC NORTHWEST...
   AS THE MID-LEVEL COLD POOL /WITH 500 MB TEMPS AS COLD AS -30C/
   ASSOCIATED WITH A SIGNIFICANT SHORT WAVE IMPULSE CONTINUES TO
   PROGRESS INLAND...AND A MOIST ONSHORE FLOW PERSISTS...SCATTERED WEAK
   THUNDERSTORM ACTIVITY MAY REMAIN POSSIBLE WEST OF THE
   WASHINGTON/NORTHERN OREGON CASCADES THROUGH MUCH OF THE DAY FRIDAY.

   ..KERR.. 12/18/2014

   CLICK TO GET WUUS02 PTSDY2 PRODUCT

   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z

        
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