MESOSCALE DISCUSSION 0726
   NWS STORM PREDICTION CENTER NORMAN OK
   1226 PM CDT MON MAY 20 2013
   
   AREAS AFFECTED...MUCH OF OK INTO NWRN TX AND SERN KS
   
   CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY 
   
   VALID 201726Z - 201930Z
   
   PROBABILITY OF WATCH ISSUANCE...95 PERCENT
   
   SUMMARY...SEVERE STORMS ARE LIKELY TO FORM THIS AFTERNOON WITH A FEW
   SIGNIFICANT TORNADOES...EXTREMELY LARGE HAIL...AND DAMAGING WINDS
   ALL POSSIBLE. TWO WATCHES WILL BE NEEDED SOON FROM KS INTO N TX.
   
   DISCUSSION...SURFACE MAP SHOWS A QUASI-STATIONARY BOUNDARY FROM SERN
   KS INTO NRN OK AND BENDING SWWD W OF THE I-44 CORRIDOR. FARTHER
   SW...A WEAK AREA OF LOW PRESSURE WAS NOTED OVER NWRN TX...ON THE
   NOSE OF A LOW LEVEL LAPSE RATE PLUME WITH DRYLINE EXTENDING SW
   ACROSS W TX.
   
   VISIBLE IMAGERY SHOWS DEEPENING CU ALONG THE BOUNDARY FROM NRN OK
   INTO SERN KS WHERE A DEEP MOIST LAYER EXISTS. GIVEN A GRADUAL
   INCREASE IN THETA-E AND BREAKS IN THE CLOUDS...THIS AREA COULD BE
   WHERE INITIAL DEVELOPMENT OCCURS. LONG HODOGRAPHS AND STEEP MIDLEVEL
   LAPSE RATES WILL FAVOR VERY LARGE HAIL...AND LOW LEVEL VEERING WIND
   PROFILES WILL BE SUFFICIENT FOR TORNADOES GIVEN AFOREMENTIONED
   THERMODYNAMIC FACTORS.
   
   TO THE S...AN EXTREMELY VOLATILE AIR MASS EXISTS WITH AN INCREASING
   CU FIELD FROM NWRN TX INTO SWRN OK WHERE STRONG HEATING PERSISTS.
   WIND FIELDS ALOFT ARE MORE THAN FAVORABLE FOR SUPERCELLS...WITH VERY
   LARGE HAIL LIKELY. ALTHOUGH SHEAR IN THE LOWEST 1-2 KM IS NOT
   PARTICULARLY STRONG...VERY LARGE VERTICAL ACCELERATIONS...AS WELL AS
   HODOGRAPH AUGMENTATION NEAR THE SFC FRONT WILL AID IN TORNADO
   POTENTIAL. HP SUPERCELLS ARE EXPECTED WITH STRONG MESOCYCLONES AND
   POSSIBLE RAIN-WRAPPED TORNADOES.
   
   ACTIVITY MAY EVENTUALLY MERGE INTO ONE OR MORE BOWS...AND RAPIDLY
   EXPAND NEWD ACROSS ERN OK LATER THIS EVENING PER MULTIPLE CONVECTION
   ALLOWING MODELS.
   
   ..JEWELL/KERR.. 05/20/2013