MESOSCALE DISCUSSION 2028
   NWS STORM PREDICTION CENTER NORMAN OK
   0356 PM CDT SAT AUG 20 2011
   
   AREAS AFFECTED...WRN AR...SWRN MO
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 202056Z - 202200Z
   
   POTENTIAL FOR DMGG WIND GUSTS AND HAIL WILL INCREASE THIS AFTERNOON
   ACROSS PORTIONS OF WRN AR AND INTO SWRN MO. A WW IS NOT CURRENTLY
   ANTICIPATED...BUT TRENDS WILL CONTINUE TO BE MONITORED.
   
   20Z SFC ANALYSIS AND RUC OBJECTIVE ANALYZED FIELDS INDICATE
   LOW-LEVEL THETA-E AXIS EXTENDS NW-SE FROM SWRN MO INTO S-CNTRL AR. A
   HOT/MOIST BOUNDARY LAYER /TEMPERATURES MID-UPPER 90S WITH DEW POINTS
   IN THE MID 70S/ WITH STEEP MIDLEVEL LAPSE RATES IS SUPPORTING MLCAPE
   VALUES RANGING FROM 3000-4500 J/KG. RECENT VISIBLE IMAGERY INDICATES
   A SMALL AREA OF TCU DEVELOPING OVER PORTIONS OF NWRN AR...NEAR A WWD
   MIXING COLD POOL FROM EARLIER CONVECTION OVER ERN MO/AR...WHILE
   LOOSELY ORGANIZED CLUSTERS OF STORMS /SOME EXHIBITING ISOLATED
   STRONG WIND GUST POTENTIAL/ SLOWLY MIGRATE NWD ACROSS W-CNTRL AR.  
   
   AN UPPER IMPULSE /NOTED IN WATER VAPOR IMAGERY AND PROFILER DATA/
   CURRENTLY LOCATED ACROSS SERN KS WILL PROGRESS EWD TOWARDS NRN
   PORTIONS OF THE DISCUSSION AREA AND SHOULD AID IN AN INCREASE IN
   CONVECTION OVER THE NEXT 1-3 HRS. THE STRONGEST MIDLEVEL FLOW
   /SAMPLED AT 30-40 KTS AT 6 KM AGL PER SGF VWP/ IS POSITIONED OVER
   SRN MO/NRN AR..AND MAY SUPPORT ORGANIZED TSTM CLUSTERS CAPABLE OF
   PRODUCING HAIL AND DMGG WINDS WITH THE STRONGEST STORMS. SOME
   UNCERTAINTY REMAINS REGARDING COVERAGE AND TIMING OF TSTM
   INITIATION...WHICH WILL PRECLUDE THE IMMEDIATE NEED FOR A WW...BUT
   TRENDS ARE BEING MONITORED.
   
   ..ROGERS.. 08/20/2011
   
   
   ATTN...WFO...LZK...SGF...SHV...EAX...TSA...
   
   LAT...LON   34239247 33429229 33069248 33059343 33239390 33999415
               35739439 37089461 37699463 38089398 38289315 38289251
               35389250 34239247