MESOSCALE DISCUSSION 0434
   NWS STORM PREDICTION CENTER NORMAN OK
   0127 AM CDT FRI APR 15 2011
   
   AREAS AFFECTED...NRN LA...AR..THE MO BOOTHEEL...WRN AR AND NW MS
   
   CONCERNING...TORNADO WATCH 136...
   
   VALID 150627Z - 150800Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 136 CONTINUES.
   
   A NEW WW WILL LIKELY BE NEEDED WITHIN THE HOUR.
   
   STRONG FORCING FOR UPWARD VERTICAL MOTION...EAST OF A SIGNIFICANT
   CLOSED LOW/UPPER TROUGH SLOWLY MOVING EASTWARD THROUGH THE CENTRAL
   PLAINS...APPEARS LIKELY TO MAINTAIN A STRONG/SEVERE MESOSCALE
   CONVECTIVE SYSTEM ACROSS ARKANSAS AND NORTHERN LOUISIANA INTO UPPER
   PORTIONS OF THE LOWER MISSISSIPPI VALLEY OVERNIGHT.  ACTIVITY IS
   EMBEDDED WITHIN A 40-50 KT DEEP LAYER MEAN FLOW FIELD ...THOUGH
   GENERALLY ORIENTED PARALLEL TO IT...WHICH IS RESULTING IN A MORE
   MODEST EASTWARD MOTION.  BUT DAMAGING WINDS AND LARGE HAIL WILL
   REMAIN A POSSIBILITY...PARTICULARLY WITH A SEGMENT LIKELY TO SURGE
   THROUGH LITTLE ROCK BETWEEN 07-08Z.
   
   BOUNDARY LAYER MOISTENING AND DESTABILIZATION APPEARS LIKELY AT
   LEAST ACROSS THE REMAINDER OF NORTHEAST ARKANSAS...THE MISSOURI
   BOOTHEEL AND WESTERN TENNESSEE BY 09Z.  THIS SHOULD OCCUR JUST PRIOR
   TO THE PASSAGE OF THE SQUALL LINE...WHICH MAY CROSS THE MISSISSIPPI
   RIVER DURING THE 09-10Z...AS A SMALLER SCALE IMPULSE ...PIVOTING
   AROUND THE CLOSED LOW...LIFTS ACROSS THE OZARK PLATEAU TOWARD THE
   LOWER OHIO VALLEY.  
   
   DISCRETE SUPERCELL DEVELOPMENT AHEAD OF THE LINE WILL REMAIN A
   POSSIBILITY.  AND...LARGE CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS WILL
   SUPPORT THE RISK FOR TORNADOES WITH THE DISCRETE ACTIVITY... AND
   PERHAPS WITHIN THE LINE.
   
   ..KERR.. 04/15/2011
   
   
   ATTN...WFO...MEG...JAN...LZK...SHV...
   
   LAT...LON   35459226 36339180 36308971 35258974 34069033 32639125
               31899320 32849386 34339292 35459226