SPC 1630Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1113 AM CDT FRI APR 27 2012 VALID 271630Z - 281200Z ...THERE IS A MDT RISK OF SVR TSTMS OVER CENTRAL/ERN KS INTO WRN MO... ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CENTRAL PLAINS INTO THE LOWER MO VALLEY... ...THERE IS A SLGT RISK OF SVR TSTMS FROM NERN GA INTO SC... ...KS/WRN MO AREA... WATER VAPOR IMAGERY INDICATES AN INTENSE UPPER VORTICITY MAX OVER EXTREME NWRN KS. THIS SYSTEM IS EXPECTED TO MOVE ENEWD AND THEN NEWD OVER THE MO RIVER VALLEY AND WEAKEN TONIGHT AS THE PRIMARY UPPER LOW OVER DEVELOPS OVER THE NRN ROCKIES...AND PROVIDE STRONG DYNAMIC FORCING FOR ASCENT. AT THE SURFACE...A CO-LOCATED DEEP LOW OVER EXTREME NWRN KS IS FORECAST TO MOVE EWD INTO CENTRAL KS THIS AFTERNOON...CONTINUING TOWARD NWRN MO TONIGHT. A WARM FRONT EXTENDING ESEWD FROM THE LOW WILL SLOWLY LIFT NWD AS EXTENSIVE CLOUDS OVER CENTRAL/ERN KS WILL BE SLOW TO DIMINISH. A DRY LINE ARCING SWD FROM THE LOW ACROSS WRN OK WILL SURGE EWD ACROSS SRN KS AND OK THIS AFTERNOON IN RESPONSE TO INCREASING DEEP LAYER WESTERLY FLOW ON THE SRN PERIPHERY OF THE UPPER SYSTEM. A NARROW LINE OF CONVECTION IS CURRENTLY INDICATED BY VISIBLE SATELLITE AND RADAR FROM NEAR HLC SWD TO EAST OF DDC...WITH BREAKS IN CLOUD COVER NOTED IMMEDIATELY IN ADVANCE OF THE CONVECTIVE LINE. STRONGER HEATING WILL ALSO OCCUR OVER MUCH OF OK WHERE FEWER CLOUDS ARE PRESENT...AND AS MOISTURE SPREADS NWD IN ASSOCIATION WITH THE WARM FRONT...SURFACE DEWPOINTS IN THE LOW/MID 60S WILL BECOME MORE COMMON OVER PARTS OF CENTRAL/ERN KS INTO WEST CENTRAL/SWRN MO BY LATER THIS AFTERNOON AND EVENING. 12Z REGIONAL RAOBS EXHIBIT STEEP MID LEVEL LAPSE RATES WHICH WILL ENHANCE INSTABILITY...WITH MLCAPE REACHING 1500-2000 J/KG. HOWEVER...THE ASSOCIATED EML WILL LIKELY CAP DEVELOPMENT OF SURFACE BASED STORMS OVER MUCH OF OK...WITH PRIMARY TSTM ACTIVITY SPREADING ACROSS PARTS OF KS INTO MO. FAVORABLE DEEP LAYER SHEAR /40-50 KT OVER THE LOWEST 6 KM/ WILL PROMOTE DEVELOPMENT OF SUPERCELLS...AND SUFFICIENT LOW LEVEL SHEAR/SRH COUPLED WITH LOW LCL HEIGHTS SUGGEST POTENTIAL FOR TORNADIC SUPERCELLS TO DEVELOP...ESPECIALLY ALONG/NEAR THE WARM FRONT WHERE A FEW STRONG TORNADOES WILL BE POSSIBLE. VERY LARGE HAIL AND DAMAGING WIND GUSTS WILL ALSO BE POSSIBLE AS STORMS PROGRESS EWD INTO WRN MO BY EVENING. THE ACTIVITY IS EXPECTED TO GRADUALLY WEAKEN AFTER 03Z AS DIURNAL BOUNDARY LAYER COOLING OCCURS. ...NERN GA INTO SC... RELATIVELY FEW CLOUDS WILL ALLOW STRONG HEATING TO OCCUR THIS AFTERNOON AS A COLD FRONT SETTLES SWD ACROSS THE AREA. SURFACE DEW POINTS NEAR 60F WILL PERMIT DEVELOPMENT OF STEEP LOW LEVEL LAPSE RATES IN THE PRE-CONVECTIVE ENVIRONMENT. MODEL GUIDANCE IS CONSISTENT INDICATING STORMS WILL DEVELOP IN A CORRIDOR FROM THE SRN APPALACHIANS ACROSS SC THIS AFTERNOON AS A WEAK PERTURBATION IN THE MID/UPPER LEVEL FLOW TRAVERSES THE REGION. WINDS ALOFT/DEEP LAYER SHEAR WILL BE SUFFICIENTLY STRONG TO SUPPORT ORGANIZED MULTI-CELL CONVECTION...WITH STRONGER CELLS CAPABLE OF PRODUCING LARGE HAIL AND STRONG WIND GUSTS. THE SEVERE THREAT IS EXPECTED TO DIMINISH AFTER SUNSET. ..WEISS/MOSIER.. 04/27/2012
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_1630.html
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