SPC 1730Z Day 2 Outlook
DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1230 PM CDT SAT MAY 26 2012 VALID 271200Z - 281200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE UPPER MS VALLEY SWWD ACROSS THE CNTRL PLAINS... ...SYNOPSIS... AN UPPER TROUGH WILL CONTINUE NEWD ACROSS THE NRN AND CNTRL PLAINS WITH UPPER LOW CENTER MOVING ACROSS MT DURING THE DAY...AND GRADUAL HEIGHT FALLS OVERSPREADING THE REGION THROUGH THE PERIOD. A LARGE AREA OF SWLY FLOW ALOFT WILL STRETCH FROM THE SRN ROCKIES NEWD INTO THE UPPER MS VALLEY...WITH A 70-110 KT MID TO UPPER LEVEL SPEED MAX EXTENDING FROM ERN CO TO THE DAKOTAS BY 00Z. AT THE SURFACE...LOW PRESSURE WILL REMAIN OVER THE DAKOTAS...WITH A DEEPENING TROUGH ACROSS CNTRL NEB AND KS. A WARM FRONT WILL LIFT NWD ACROSS CNTRL MN AND WI DURING THE DAY. BOUNDARY LAYER DEWPOINTS WILL GENERALLY BE IN THE 60S F ACROSS THE WARM SECTOR...WITH MID TO UPPER 60S OVER MN/WI AND UPPER 50S/LOWER 60S OVER CNTRL KS INTO WRN OK. WHILE SOME ACTIVITY WILL BE POSSIBLE EARLY ALONG THE WARM FRONT WITH A 40-50 KT SWLY LOW LEVEL JET...THE PRIMARY SEVERE THREAT WILL BE ALONG THE DRYLINE AND DEVELOPING COLD FRONT DURING THE AFTERNOON AND EVENING. OTHER AREAS OF ISOLATED STORMS WILL EXIST OVER NY AND PA...NEAR THE CREST OF THE UPPER RIDGE. ...MN...WRN WI... AREAS OF ELEVATED THUNDERSTORMS ARE LIKELY TO BE ONGOING OVER CNTRL AND NRN MN INTO FAR NRN WI ON THE NOSE OF THE LOW LEVEL JET. THIS ACTIVITY WILL BE CAPABLE OF LARGE HAIL...BUT WILL SHIFT NWD OUT OF THE AREA DURING THE MORNING. BEHIND THIS ACTIVITY...SWLY WINDS WILL INCREASE WITH STRONG HEATING. BY AFTERNOON...STRONG INSTABILITY WILL HAVE DEVELOPED...AND CIN WILL LIKELY BE FULLY ERODED BY LATE AFTERNOON. WITH SOMEWHAT MERIDIONAL FLOW ALOFT...SURFACE CONVERGENCE WILL NOT BE STRONG...BUT SUFFICIENT...AND IN A ZONE OF FAVORABLE DIFFERENTIAL DIVERGENCE. THIS WILL FAVOR THE RAPID DEVELOPMENT OF DISCRETE SUPERCELLS CAPABLE OF VERY LARGE HAIL AND A FEW TORNADOES. SOME OF THESE STORMS MAY DEVELOP INTO BOWS WITH SWATHS OF DAMAGING WINDS. ...SIOUX RIVER VALLEY INTO ERN NEB...CNTRL KS...NWRN OK CONTINUING SWWD ALONG THE DRYLINE AND EVENTUALLY THE COLD FRONT WILL BE RAPID DEVELOPMENT OF SEVERE STORMS BY LATE AFTERNOON PERHAPS AS FAR S AS THE NERN TX PANHANDLE. STRONG VEERING WINDS WITH HEIGHT AND STEEP LAPSE RATES WILL FAVOR SUPERCELLS...ALBEIT A BIT HIGH BASED FOR A WIDESPREAD TORNADO THREAT. VERY LARGE HAIL WILL BE THE PRIMARY THREAT...WITH LOCALLY SEVERE WIND GUSTS AND PERHAPS A COUPLE BRIEF/WEAK TORNADOES WITH SUCH HIGH LCLS. THE THREAT SHOULD REMAIN IN A RELATIVELY NARROW ZONE...AS CAPPING INCREASES AWAY FROM THE BOUNDARY AFTER 00Z. ...PA...WRN NY... DAYTIME HEATING COMBINED WITH DEWPOINTS IN THE 60S WILL YIELD MUCAPE AROUND 1500-2000 J/KG BY AFTERNOON. SHEAR WILL NOT BE STRONG...BUT WNWLY MEAN FLOW AROUND 20-25 KT MAY HELP SOME ACTIVITY TO BECOME LOOSELY ORGANIZED...WITH LOCALLY STRONG/GUSTY WINDS...AND MARGINALLY SEVERE HAIL. LACK OF APPRECIABLE FORCING IS LIKELY TO RESULT IN ONLY ISOLATED DEVELOPMENT. ..JEWELL.. 05/26/2012
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day2otlk_1730.html
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