SPC 1300Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0751 AM CDT WED MAY 23 2012 VALID 231300Z - 241200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS SWRN MN/WRN IA/SERN SD/SRN AND ERN NEB/NWRN AND N-CNTRL KS... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE CAROLINAS AND FAR SERN VA... ...SYNOPSIS... A LARGE TROUGH OVER THE WRN HALF OF THE CONUS WILL DIG SEWD AS MID-LEVEL HEIGHT FALLS OVERSPREAD THE CNTRL/SRN ROCKIES AND CNTRL PLAINS...WITH A BELT OF STRONG MID-LEVEL FLOW WITHIN THE BROAD BASE OF THE TROUGH. AN ASSOCIATED SFC COLD FRONT EXTENDING SSWWD FROM THE ND/MN BORDER TO A LOW OVER THE KS/CO BORDER WILL GRADUALLY PROGRESS EWD/SEWD. BROAD/MOSTLY WEAK MID/UPPER-LEVEL CYCLONIC FLOW WILL BE FOUND FROM THE NRN GULF OF MEXICO EXTENDING NEWD ACROSS THE SERN STATES INTO THE MID ATLANTIC. ...SWRN MN/WRN IA/SERN SD/SRN AND ERN NEB/NWRN AND N-CNTRL KS THIS AFTERNOON INTO TONIGHT... AS A PLUME OF THE ELEVATED MIXED LAYER IS ADVECTED INTO THE REGION BY THE ENHANCED MID-LEVEL FLOW ACCOMPANYING THE AMPLIFYING TROUGH...STEEP MID-LEVEL LAPSE RATES WILL OVERLAY A CORRIDOR OF MODEST BOUNDARY-LAYER MOISTURE NEAR AND EAST OF THE COLD FRONT. WITH WARM-SECTOR BOUNDARY-LAYER DEWPOINTS IN THE 50S TO PERHAPS AROUND 60F -- LIMITED BY VERTICAL MIXING AND DISTANCE FROM SUBSTANTIALLY RICHER LOW-LEVEL MOISTURE -- 1000-2000 J/KG OF MLCAPE WILL LIKELY DEVELOP THIS AFTERNOON. AND...WITH INCREASING LARGE-SCALE ASCENT/DIURNAL HEATING CONTRIBUTING TO THE EROSION OF THE INITIALLY STRONG EML CAP...SFC-BASED STORMS WILL LIKELY DEVELOP INVOF THE FRONT BY LATE AFTERNOON. THE COMBINATION OF MODERATE INSTABILITY AND MODERATE TO STRONG DEEP SHEAR -- STRONGEST BEHIND THE FRONT -- WILL SUPPORT ORGANIZED STORMS INCLUDING BOWING LINE SEGMENTS AND POSSIBLE SUPERCELLS. THIS ACTIVITY WILL BE CAPABLE OF PRODUCING LARGE HAIL...ESPECIALLY WITH SUSTAINED SUPERCELL STRUCTURES...ALONG WITH SVR WIND...PARTICULARLY WITH SFC-BASED CONVECTION. LOW-LEVEL SHEAR MAY BE SUFFICIENT TO SUPPORT THE THREAT FOR A TORNADO OR TWO INTO THE EVENING...THOUGH LIMITED LOW-LEVEL MOISTURE AND EVENTUAL FRONTAL UNDERCUTTING/UPSCALE CONVECTIVE GROWTH SHOULD LIMIT THE OVERALL TORNADO THREAT. ...NERN CO THIS AFTERNOON INTO EARLY EVENING... MODESTLY MOIST UPSLOPE FLOW BENEATH STRONG MID/HIGH-LEVEL FLOW WILL SUPPORT ISOLATED TO SCATTERED THUNDERSTORMS WITH A THREAT FOR SVR HAIL/WIND. ONLY MARGINAL DESTABILIZATION SHOULD PREVENT A MORE SUBSTANTIAL SVR THREAT FROM EVOLVING. ...SOUTHEAST STATES/CAROLINAS/SERN VA THIS AFTERNOON INTO EARLY EVENING... A ZONE OF COOL MID-LEVEL TEMPERATURES /-14C TO -17C AT 500 MB/ WILL OVERLAY AREAS OF STRONG SFC HEATING AND A NNE-SSW-ORIENTED WEAK SFC FRONT. STEEP LAPSE RATES AND MODEST DEEP SHEAR WILL SUPPORT A THREAT FOR MULTICELL STORMS CAPABLE OF SVR HAIL AND WIND...ESPECIALLY ACROSS THE PIEDMONT/COASTAL AREAS OF THE CAROLINAS AND FAR SERN VA. ...SRN MS AND ERN LA THIS AFTERNOON... STRONG HEATING AMIDST A NEWD-ADVANCING WARM FRONT WILL SUPPORT ISOLATED TO WIDELY SCATTERED TSTMS. BOUNDARY-LAYER DEWPOINTS IN THE LOWER 60S NEAR AND SW OF THE FRONT WILL SUPPORT MODERATE TO STRONG DESTABILIZATION...WITH STEEP LOW-LEVEL LAPSE RATES LIKELY YIELDING DCAPE VALUES IN EXCESS OF 1000 J/KG. VERY WEAK FLOW THROUGHOUT THE TROPOSPHERE WILL SUPPORT A PULSE CONVECTIVE MODE...AND A LOW THREAT FOR DMGG WIND GUSTS AND PERHAPS MARGINALLY SVR HAIL CANNOT BE RULED OUT WITH THE STRONGEST STORMS. ..COHEN/CORFIDI.. 05/23/2012
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_1300.html
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