MESOSCALE DISCUSSION 0771
   NWS STORM PREDICTION CENTER NORMAN OK
   0931 PM CDT FRI MAY 08 2009
   
   AREAS AFFECTED...SOUTHERN/EASTERN OK AND NORTHERN AR
   
   CONCERNING...TORNADO WATCH 274...
   
   VALID 090231Z - 090400Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 274 CONTINUES.
   
   TORNADO WATCH 274 CONTINUES UNTIL 07Z ACROSS PORTIONS OF
   SOUTHERN/EASTERN OK AND THE NORTHERN HALF OF AR.
   
   SCATTERED TSTMS/SUPERCELLS CONTINUE TO DEVELOP WITHIN LOW LEVEL
   FRONTAL CONVERGENCE ZONE AND MOISTURE/INSTABILITY AXIS FROM SOUTH
   CENTRAL OK NORTHEASTWARD INTO FAR NORTHERN AR...WITH THE MOST ROBUST
   STORMS ALONG THE RED RIVER SOUTH OF ARDMORE AS OF 0220Z. THESE
   STORMS MAY CONTINUE TO GRADUALLY CONSOLIDATE AND PERHAPS FORWARD
   PROPAGATE INTO FAR NORTH CENTRAL TX.
   
   THE 00Z NORMAN OBSERVED RAOB SAMPLED RATHER STRONG BUOYANCY WITH
   AROUND 2400 J/KG MLCAPE AND VERY STEEP 8.0 C/KM MID LEVEL LAPSE
   RATES...WITH VEERING WIND PROFILES AND 40-50 KT OF HIGH LEVEL FLOW
   BEING WELL-SUPPORTIVE OF ROTATING STORMS. AMPLE MOISTURE /UPPER 60S
   TO LOWER 70S F SURFACE DEWPOINTS/ IS CURBING THE NOCTURNAL TENDENCY
   FOR BOUNDARY LAYER DECOUPLING...AND AN ISOLATED/BRIEF TORNADO CANNOT
   BE RULED OUT. HOWEVER...THE PRIMARY SEVERE THREAT SHOULD DECIDEDLY
   REMAIN LARGE HAIL OWING TO 1/ TENDENCY FOR DEVELOPMENT TO OCCUR
   ALONG THE IMMEDIATE COOL/NORTH SIDE OF THE SURFACE BOUNDARY...2/
   MODEST SOUTHWESTERLY FLOW OF 15-30 KT AROUND 1 KM...ALONG WITH
   WEAK/LIMITED LARGE SCALE FORCING PER WATER VAPOR IMAGERY.
   
   ..GUYER.. 05/09/2009
   
   
   ATTN...WFO...LZK...SHV...TSA...FWD...OUN...
   
   LAT...LON   34279769 35739585 36339397 36259145 34959228 33619696
               34279769