MESOSCALE DISCUSSION 0807
   NWS STORM PREDICTION CENTER NORMAN OK
   0736 PM CDT WED MAY 18 2011
   
   AREAS AFFECTED...ERN CO
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 190036Z - 190130Z
   
   ISOLATED SUPERCELL WILL CONTINUE TO MOVE ENE ACROSS PORTIONS OF ERN
   CO DURING THE NEXT HR OR TWO. LARGE HAIL/DAMAGING WIND GUSTS AND A
   FEW TORNADOES WILL BE POSSIBLE WITH THIS STORM...BUT SVR WEATHER
   COVERAGE IS EXPECTED TO BE LIMITED...MAKING WW ISSUANCE UNCERTAIN.
   
   LARGE SCALE ASCENT ASSOCIATED WITH PV LOBE AT THE BASE OF GREAT
   BASIN UPPER TROUGH IS BEGINNING TO EMERGE OVER THE CNTRL HIGH
   PLAINS. THIS ASCENT COMBINED WITH AFTERNOON BOUNDARY LAYER
   DESTABILIZATION...MODEST UPSLOPE MOISTURE TRANSPORT /MID 40S
   DEWPOINTS/...AND DEVELOPMENT OF WEAK CONVECTIVE INSTABILITY HAS
   SUPPORTED ISOLATED THUNDERSTORM DEVELOPMENT OVER ERN CO /STORM
   LOCATED IN KIOWA COUNTY AT 0020Z/. COMBINATION OF ELY LOW-LEVEL
   WINDS VEERING TO 60 KT MIDLEVEL SWLYS IS CONTRIBUTING TOWARD VERY
   FAVORABLE LOW AND DEEP-LAYER VERTICAL SHEAR PROFILES FOR SUPERCELL
   DEVELOPMENT. THE FAVORABLE SHEAR AND STEEP MIDLEVEL LAPSE RATES WILL
   SUPPORT THE POTENTIAL FOR LARGE HAIL IN ADDITION TO DAMAGING WIND
   GUSTS. STRONG LOW-LEVEL SHEAR /EFFECTIVE SRH IN EXCESS OF 500 M2 S-2
   PER RUC FORECAST SOUNDINGS/ WILL ALSO SUPPORT A TORNADO THREAT.
   GIVEN THE BOUNDARY LAYER SHOULD BEGIN TO COOL DURING THE NEXT FEW
   HRS...AND ONGOING SUPERCELL WILL MOVE OFF THE INSTABILITY AXIS WITH
   TIME...IT IS UNCERTAIN HOW LONG THE SVR WEATHER THREAT WILL PERSIST.
   HOWEVER...CONTINUED LOW-LEVEL UPSLOPE FLOW OVER THE AREA MAY SUPPORT
   STORM REGENERATION...THUS CONVECTIVE TRENDS WILL BE MONITORED FOR
   POSSIBLE WW ISSUANCE.
   
   ..GARNER.. 05/19/2011
   
   
   ATTN...WFO...GLD...PUB...BOU...
   
   LAT...LON   38850398 39270350 39330250 38830201 38130210 37910272
               37920327 38080383 38850398