MESOSCALE DISCUSSION 1320
   NWS STORM PREDICTION CENTER NORMAN OK
   0134 PM CDT MON JUN 20 2011
   
   AREAS AFFECTED...CENTRAL/EASTERN KS AND OK
   
   CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 
   
   VALID 201834Z - 202030Z
   
   INCIPIENT DEEP CONVECTIVE DEVELOPMENT IS EXPECTED TO OCCUR BY AROUND
   MID AFTERNOON ACROSS EAST-CENTRAL KS INTO PORTIONS OF CENTRAL
   OK...AND A WATCH WILL BE NEEDED BY AROUND MID AFTERNOON.
   
   AN INCREASE IN MID LEVEL CONVECTION...LIKELY JUST ABOVE AN ERODING
   CAP VIA IMPLIED LARGE SCALE FORCING FOR ASCENT...HAS OCCURRED EARLY
   THIS AFTERNOON IN NORTH-SOUTH BANDS ACROSS CENTRAL KS/NORTH-CENTRAL
   OK COINCIDENT WITH A DRY LINE/SURFACE TROUGH DEMARCATED MOIST AXIS.
   FURTHERMORE...A GRADUALLY INCREASING CU FIELD HAS ALSO BEEN RECENTLY
   NOTED WITHIN THE HOTTER/DEEPLY MIXED AIR NEAR/WEST OF THE DRYLINE.
   SPECIAL 18Z OBSERVED RAOBS FROM TOPEKA KS/NORMAN OK STILL REFLECT A
   SUBSTANTIAL CAP AROUND 700-750 MB...BUT CONSIDERABLE
   MOISTENING/COOLING HAS OCCURRED BELOW THE CAP IN EACH CASE SINCE
   12Z.
   
   AS THE CLOSED UPPER LOW CURRENTLY OVER THE SOUTH-CENTRAL HIGH PLAINS
   SHIFTS ENE AND GRADUALLY TAKES ON A MORE NEGATIVE TILT AND
   CONSIDERABLE HEIGHT FALLS OVERSPREAD THE REGION...AT LEAST SCATTERED
   SURFACE BASED CONVECTION SHOULD DRAMATICALLY INCREASE THROUGH
   MID/LATE AFTERNOON ESPECIALLY ACROSS EAST-CENTRAL KS/NORTH-CENTRAL
   OK. VERY STRONG/BUT GRADUALLY BACKING FLOW ALOFT WILL SUPPORT
   SUPERCELLS WITHIN A VERY STEEP LAPSE RATE AND MODERATE TO STRONGLY
   UNSTABLE ENVIRONMENT. INITIAL MODE SUPERCELLS CAPABLE OF LARGE HAIL
   WILL BE POSSIBLE. WHILE A HOT BOUNDARY LAYER/RELATIVELY HIGH
   TEMPERATURE-DEWPOINT SPREADS WILL TEND TO CURB THE RISK...A TORNADO
   THREAT CANNOT BE RULED OUT. OTHERWISE...DEEP LAYER SHEAR ORIENTED
   PARALLEL TO THE INITIATING BOUNDARY...WITH A VEER-BACK-VEER PATTERN
   NOTED IN FORECAST SOUNDINGS/OBSERVATIONAL DERIVED WINDS...IMPLIES A
   CONGEALING/MORE LINEAR MODE THROUGH EARLY EVENING WITH A MARKEDLY
   INCREASING DAMAGING WIND POTENTIAL ESPECIALLY GIVEN THE STEEP LAPSE
   RATES/WATER LOADING.
   
   ..GUYER.. 06/20/2011
   
   
   ATTN...WFO...TSA...TOP...ICT...OUN...DDC...
   
   LAT...LON   38939840 39139793 39809733 39419632 36429641 35469687
               35189743 35319845 36499837 38939840