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Mesoscale Discussion 231
MD 231 graphic
   
   MESOSCALE DISCUSSION 0231
   NWS STORM PREDICTION CENTER NORMAN OK
   0135 AM CST THU MAR 13 2003
   
   AREAS AFFECTED...SRN IL...WRN KY...WRN TN...NRN AR
   
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL 
   
   VALID 130735Z - 130930Z
   
   NEW WWS ARE NOT CURRENTLY ANTICIPATED.
   
   MID/UPPER TROUGH AXIS CONTINUES TO SHIFT EASTWARD THROUGH THE
   MIDDLE MISSISSIPPI VALLEY ACCOMPANIED BY WEAK COLD FRONT.  IN
   LOW-LEVEL WARM ADVECTION ZONE AHEAD OF FRONT...VIGOROUS
   CONVECTIVE SYSTEM IS ONGOING FROM PARTS OF CENTRAL/SOUTHERN
   ILLINOIS INTO NORTHWEST ARKANSAS/SOUTHWEST MISSOURI.  ACTIVITY IS
   NOW MOSTLY ROOTED ABOVE RELATIVELY COOL/STABLE BOUNDARY
   LAYER...WHICH APPEARS LIKELY TO INHIBIT STRONG DOWNDRAFTS.  GUSTY
   WINDS TO 30 KTS OR SO...ASSOCIATED WITH DOWNWARD MOMENTUM
   TRANSFER...MAY ACCOMPANY STRONGEST CELLS NEXT FEW HOURS...BUT
   LARGE HAIL SHOULD REMAIN PRIMARY SEVERE THREAT THROUGH THE
   REMAINDER OF THE NIGHT...AND EVEN THIS IS EXPECTED TO BECOME
   RATHER ISOLATED/SPORADIC.
   
   MUCH OF ACTIVITY ACROSS CENTRAL/SOUTHERN ILLINOIS IS EXPECTED TO
   WEAKEN IN PROGRESSIVELY MORE STABLE ENVIRONMENT ACROSS THE LOWER
   OHIO VALLEY.  STEEPER MID-LEVEL LAPSE RATES ARE PRESENT ON
   NORTHERN PERIPHERY OF ERODING LOW-LEVEL THERMAL RIDGE ACROSS
   WESTERN ARKANSAS ...AND THIS MAY HELP MAINTAIN STRONGER
   CONVECTION WHICH WILL APPROACH THE MEMPHIS TN/LITTLE ROCK AR
   AREAS TOWARD 12Z.
   
   ..KERR.. 03/13/2003
   
   
   ATTN...WFO...PAH...MEG...LSX...LZK...SGF...
   
   35889314 36379197 37369020 38318941 38368864 37398823
   36438814 35098950 34849111 34759304 
   
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