MESOSCALE DISCUSSION 1574
   NWS STORM PREDICTION CENTER NORMAN OK
   0211 AM CDT THU JUL 16 2009
   
   AREAS AFFECTED...NRN AR AND WRN TN
   
   CONCERNING...HEAVY RAINFALL 
   
   VALID 160711Z - 160945Z
   
   HVY RNFL WITH HRLY RATES 1-3 INCHES CAN BE EXPECTED THROUGH AT LEAST
   10Z IN A 30 MILE WIDE CORRIDOR EXTENDING FROM 20W KHRO-25NW KBVX-25
   SW KDYR. IN ADDITION...ISOLD LARGE HAIL AND DMGG WIND GUSTS WILL BE
   POSSIBLE.
   
   WATER VAPOR IMAGERY SHOWS A WEAK MID-LVL SPEED MAX TRANSLATING
   ACROSS CNTRL KS EARLY THIS MORNING WITH A 15-20 KT SSWLY LLJ NOTED
   DOWNSTREAM IN OK/AR.  THOUGH THE JET IS WEAK...SUSTAINED
   CONVERGENCE/WEAK WARM ADVECTION INVOF AN OUTFLOW BOUNDARY DRAPED
   ACROSS SWRN TN AND NRN AR WAS YIELDING NUMEROUS TSTMS.  STORMS HAVE
   FORMED IN A W TO E BAND ACROSS NRN AR WITH ANOTHER CLUSTER NORTH OF
   THE KMEM AREA.  
   
   GPS PWAT PLOT SHOWS PLENTIFUL MOISTURE AVAILABLE WITH VALUES IN
   EXCESS OF 1.8 INCHES.  RELATIVELY HIGH FREEZING LEVELS...WEAK CLOUD
   BEARING SHEAR AND TENDENCY FOR STORMS TO BACKBUILD SUGGEST THAT
   TRAINING HVY RNFL WILL BE A THREAT ACROSS NRN AR AND WRN TN THROUGH
   DAYBREAK.  
   
   IN ADDITION...VERY STEEP LAPSE RATES EVIDENT IN 00Z SOUNDINGS WILL
   COMPENSATE SOMEWHAT FOR WEAK VERTICAL SHEAR AND CONTRIBUTE TO ISOLD
   LARGE HAIL.  ISOLD DMGG WINDS CAN ALSO BE EXPECTED...PARTICULARLY AS
   STORMS ATTAIN STRONGER COLD POOLS.
   
   ..RACY.. 07/16/2009
   
   
   ATTN...WFO...MEG...LZK...TSA...
   
   LAT...LON   36339386 36469277 35948965 35578941 35388988 35599158
               35919311 36239385 36339386