MESOSCALE DISCUSSION 0851
   NWS STORM PREDICTION CENTER NORMAN OK
   1242 PM CDT SUN MAY 22 2011
   
   AREAS AFFECTED...PORTIONS OF W-CNTRL/NWRN TX INTO S-CNTRL OK
   
   CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 
   
   VALID 221742Z - 221945Z
   
   ISOLATED TO WIDELY SCATTERED SUPERCELLS WILL LIKELY DEVELOP ALONG
   THE DRYLINE BY MID-AFTERNOON. PRIMARY INITIAL THREAT WILL BE LARGE
   HAIL /SOME SIGNIFICANT/. THE PROBABILITY OF ONE OR MORE WW ISSUANCES
   BY 20Z IS 80 PERCENT.
   
   17Z SUBJECTIVE SURFACE ANALYSIS PLACED DRYLINE FROM AROUND 40 E SPS
   SWWD TO 60 SE MAF. RECENT VISIBLE SATELLITE IMAGERY INDICATES CU
   DEEPENING ALONG AND AHEAD OF THE DRYLINE. INCIPIENT TSTM FORMATION
   APPEARS PROBABLE BY 19Z AS AIR MASS HAS BECOME LARGELY UNCAPPED
   BASED ON MODIFIED 12Z DRT/FWD RAOBS WITH MLCAPE AOA 4000 J/KG. THIS
   EXTREME INSTABILITY COUPLED WITH 35 TO 40 KT W/SWLYS AT 500 MB WILL
   BE MORE THAN SUFFICIENT FOR SUPERCELLS PRIMARILY PRODUCING VERY
   LARGE HAIL.
   
   MODEST UNCERTAINTY EXISTS OVER THE SPATIOTEMPORAL EXTENT OF THE
   TORNADO THREAT. ACROSS THE CONCHO VALLEY/BIG COUNTRY...LOW-LEVEL
   SHEAR SHOULD REMAIN WEAK THROUGH MOST OF THE AFTERNOON BEFORE
   INCREASING NEAR AND AFTER 00Z AS MASS RESPONSE OCCURS DOWNSTREAM OF
   A WRN CONUS UPPER-LEVEL TROUGH. FARTHER EAST... STRONGER LOW-LEVEL
   FLOW SAMPLED IN PROFILER/VWP DATA ALONG THE I-35 CORRIDOR SHOULD
   LARGELY BE MAINTAINED THROUGH THE LATE AFTERNOON AND GIVEN THE
   DEGREE OF INSTABILITY WILL FAVOR A THREAT FOR TORNADOES.
   
   ..GRAMS.. 05/22/2011
   
   
   ATTN...WFO...FWD...OUN...SJT...MAF...
   
   LAT...LON   34329783 34879749 34899650 34319637 32549758 31499895
               31220006 31360108 31640119 31910099 32499995 32859874
               34329783