DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0751 AM CDT FRI MAY 25 2012 VALID 251300Z - 261200Z ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT FROM THE MID-MO VALLEY SWD INTO THE SRN PLAINS... ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO EVENING ACROSS PARTS OF THE LOWER GREAT LAKES... ...SYNOPSIS... LARGE-SCALE PATTERN WILL UNDERGO AMPLIFICATION THIS PERIOD OWING TO THE SEWD DEVELOPMENT OF UPPER TROUGH THROUGH THE GREAT BASIN INTO LOWER CO VALLEY...AND SUBSEQUENT NWD/NEWD EXPANSION OF SUBTROPICAL RIDGE INTO MID-MS AND OH VALLEYS. WITHIN THIS BROADER-SCALE PATTERN...SHORT-WAVE TROUGH OVER THE UPPER GREAT LAKES INTO WRN ONTARIO WILL DE-AMPLIFY WHILE TRANSLATING ENEWD INTO QUEBEC. AT THE SURFACE...COLD FRONT ATTENDANT TO THE GREAT LAKES SHORT-WAVE TROUGH WILL ADVANCE EWD TO THE LEE OF LAKE ERIE/ONTARIO BY LATE AFTERNOON/EARLY EVENING WITH THE BOUNDARY TRAILING WSWWD INTO THE CNTRL PLAINS WHERE IT WILL BE LIFTING NWD AS A WARM FRONT. A DRYLINE WILL EXTEND FROM THE WARM FRONT OVER WRN KS SWD TO ALONG THE TX/OK BORDER AND INTO THE PECOS RIVER VALLEY DURING THE PEAK OF THE DIURNAL HEATING CYCLE. ...MID-MO VALLEY INTO THE SRN PLAINS... SURFACE-BASED TSTM DEVELOPMENT REMAINS UNCERTAIN ALONG THE WARM FRONT AND DRYLINE THIS AFTERNOON/EVENING OWING TO THE RISING MIDLEVEL HEIGHTS DOWNSTREAM FROM WRN U.S. TROUGH. HOWEVER...SOME MESOSCALE AND CONVECTION-ALLOWING MODEL GUIDANCE DOES SUGGEST THAT STRONG DIABATIC WARMING WITHIN AIR MASS W OF DRYLINE FROM SWRN KS INTO W-CNTRL TX MAY BE SUFFICIENT TO INITIATE ISOLATED TSTMS BY LATE AFTERNOON/EARLY EVENING. AS SUCH...HIGHER SEVERE PROBABILITIES AND A CATEGORICAL SLIGHT RISK HAVE BEEN EXTENDED SWD INTO THE ERN TX PNHDL/WRN OK. 12Z OBSERVED SOUNDINGS WITHIN THE WARM SECTOR INDICATE THE POTENTIAL FOR STRONG AIR MASS DESTABILIZATION TODAY /MLCAPE OF 2000-4000 J PER KG/ OWING TO THE COLLOCATION OF A MOIST BOUNDARY LAYER WITH STEEP MIDLEVEL LAPSE RATES ATTENDANT TO EML. THE STRONGEST DEEP-LAYER SHEAR /50-60 KT/ WILL RESIDE ACROSS WARM FRONT WITH A GENERAL DECREASE WITH SWD EXTENT ALONG DRYLINE. IN AREAS WHERE THE VERTICAL SHEAR IS WEAKER...THE STRONG INSTABILITY WILL COMPENSATE WITH SUPERCELLS LIKELY ANYWHERE SURFACE-BASED STORMS CAN INITIATE AND BECOME SUSTAINED. LARGE HAIL WILL BE THE PRIMARY HAZARD...THOUGH THE THREAT FOR TORNADOES WILL INCREASE THIS EVENING ACROSS NRN EXTENSION OF DRYLINE AND WARM FRONT WHERE LOW-LEVEL SHEAR IS ENHANCED. THE NOCTURNAL ENHANCEMENT TO THE LLJ WILL LIKELY GIVE RISE TO AN INCREASE IN ELEVATED TSTMS ACROSS THE MID-MO VALLEY TONIGHT WHERE THE PRESENCE OF MODERATE-STRONG INSTABILITY WILL PROMOTE EMBEDDED SUPERCELLS CAPABLE OF MAINLY LARGE HAIL. ...MO THIS MORNING... A CLUSTER OF ELEVATED TSTMS IS ONGOING THIS MORNING INVOF OF MKC WITHIN A ZONE OF WEAK LOW-LEVEL WAA N OF SURFACE FRONT. 12Z SGF SOUNDING SUGGESTS THAT ENVIRONMENT IS MODERATELY UNSTABLE FOR PARCELS ORIGINATING ABOVE STABLE SURFACE LAYER WITH MUCAPE OF 2000-2500 J/KG. ISOLATED OCCURRENCES OF MARGINALLY SEVERE HAIL ARE POSSIBLE THIS MORNING BEFORE STORMS GRADUALLY WEAKEN LATER TODAY. ...LOWER GREAT LAKES... STRONG FORCING FOR ASCENT/HEIGHT FALLS ATTENDANT TO DE-AMPLIFYING SHORT-WAVE TROUGH WILL REMAIN N OF REGION TODAY WITH CONVERGENCE ALONG THE COLD FRONT AND/OR DEVELOPING LAKE BREEZE CIRCULATION SERVING AS THE FOCUS FOR DIURNAL STORM INITIATION. DAYTIME HEATING COUPLED WITH DEWPOINTS IN THE LOWER 60S WILL CONTRIBUTE TO A MODERATELY UNSTABLE AIR MASS BY AFTERNOON WITH MLCAPE VALUES APPROACHING 1000-2000 J/KG. THIS INSTABILITY WILL COINCIDE WITH A GRADUALLY STRENGTHENING DEEP-LAYER WIND FIELD ALONG SRN PERIPHERY OF SHORT-WAVE TROUGH WITH ENVIRONMENT BECOMING SUPPORTIVE OF ORGANIZED/ROTATING STORMS CAPABLE OF DAMAGING WINDS...LARGE HAIL AND PERHAPS A TORNADO. ..MEAD/ROGERS.. 05/25/2012 NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z CURRENT UTC TIME: 1310Z (8:10AM), RELOAD THIS PAGE TO UPDATE THE TIME
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