MESOSCALE DISCUSSION 1696
   NWS STORM PREDICTION CENTER NORMAN OK
   0141 AM CDT TUE JUL 28 2009
   
   AREAS AFFECTED...PARTS OF NE TX INTO THE LA/AR BORDER AREA
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 280641Z - 280815Z
   
   HEAVY RAIN AND FREQUENT CLOUD TO GROUND LIGHTNING APPEAR TO BE THE
   PRIMARY CONVECTIVE HAZARDS LATE TONIGHT.  THUS...A SEVERE WEATHER
   WATCH IS NOT CURRENTLY ANTICIPATED...BUT TRENDS WILL BE MONITORED.
   
   VIGOROUS CONVECTIVE DEVELOPMENT IS NOW ONGOING ACROSS PARTS OF
   NORTHEAST TEXAS...NORTHWEST THROUGH NORTHEAST OF LONGVIEW.  FORCING
   ASSOCIATED WITH A SHORT WAVE IMPULSE/SPEED MAXIMUM EMBEDDED WITHIN A
   WEAK...BROADLY CYCLONIC UPPER FLOW REGIME APPEARS TO BE CONTRIBUTING
   TO THE EVOLVING STORM CLUSTER...WHICH IS EXPECTED TO CONTINUE TO
   EXPAND/INTENSIFY THROUGH DAY BREAK.  WHILE 20 KT WESTERLY DEEP LAYER
   MEAN FLOW WILL TEND TO ADVECT ACTIVITY EASTWARD ALONG/OR JUST SOUTH
   OF THE LOUISIANA/ARKANSAS BORDER...A SOUTHWESTERLY LOW-LEVEL JET
   WILL LIKELY CONTINUE TO GRADUALLY STRENGTHEN LATE TONIGHT ACROSS
   EASTERN TEXAS.  MUCH OF MODEL GUIDANCE SUGGESTS A 30-40 KT 850 MB
   SPEED MAXIMUM WILL BE IN THE PROCESS OF NOSING THROUGH THE ARKLATEX
   BY 10-12Z.  THIS IS EXPECTED TO SUPPORT BACKBUILDING AND TRAINING
   STORMS NEAR/NORTH AND WEST OF THE LONGVIEW/SHREVEPORT AREAS.  
   
   IN THE PRESENCE OF A VERY MOIST LOW-LEVEL ENVIRONMENT...
   CHARACTERIZED BY PRECIPITABLE WATER OF 2.0-2.25+ INCHES...WITH
   SIZABLE CAPE THROUGH A FAVORABLE PORTION OF THE MIXED PHASE LAYER
   ...EXCESSIVE RAINFALL AND FREQUENT CLOUD TO GROUND LIGHTNING STRIKES
   SEEM TO BE THE PRIMARY CONVECTIVE HAZARDS.  SATURATED LOWER/MID
   TROPOSPHERIC THERMODYNAMIC PROFILES WILL PROBABLY LIMIT THE
   POTENTIAL FOR DAMAGING WINDS.  BUT...THIS COULD BE OFFSET SOMEWHAT
   BY PRECIPITATION LOADING AND THE STRENGTHENING LOW-LEVEL FLOW
   FIELDS.
   
   ..KERR.. 07/28/2009
   
   
   ATTN...WFO...LZK...SHV...FWD...
   
   LAT...LON   33149544 33419494 33569446 33689350 33639318 33399258
               33209232 32919220 32449236 32109281 31909401 31929474
               32069527 32509554 32739558 33149544