SPC 1630Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1124 AM CDT MON APR 08 2013 VALID 081630Z - 091200Z ...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTERNOON INTO TONIGHT FROM ERN CO TO THE MID MO VALLEY... ...SYNOPSIS... AN INTENSE MIDLEVEL TROUGH AND ASSOCIATED 110-120 KT JET STREAK WILL CONTINUE TO DIG ESEWD OVER AZ/NM THROUGH TONIGHT. AT THE SURFACE...LEE CYCLOGENESIS IS EXPECTED ACROSS SE CO...WITH A SHARPENING DRYLINE ARCING TO THE SE NEAR THE WRN OK BORDER...AND THE SURFACE WARM SECTOR WILL BE ESTABLISHED ACROSS THE CENTRAL/SRN PLAINS TO THE MS RIVER. MEANWHILE...A SURGE OF CONTINENTAL POLAR AIR WILL SPREAD SWD ACROSS THE NRN HIGH PLAINS...REINFORCING A STRONG FRONT FROM NE CO INTO NEB BY TONIGHT. ...CENTRAL/SRN PLAINS THROUGH TONIGHT... BOUNDARY LAYER DEWPOINTS HAVE SLOWLY INCREASED THE PAST TWO DAYS TO THE MID-UPPER 60S ACROSS S TX...WITH LOW 60S AS FAR N AS OK AND MID-UPPER 50S ACROSS THE SE THREE QUARTERS OF KS. MEANWHILE...A RELATIVELY WARM EML...SAMPLED BY THE 12Z SOUNDINGS ACROSS OK/TX...WILL SPREAD NEWD OVER KS AS MIDLEVEL FLOW GRADUALLY BACKS IN ADVANCE OF THE DEEP TROUGH TO THE W. WITH ONLY LOW-LEVEL ASCENT EXPECTED IN A NARROW ZONE ALONG THE DRYLINE THIS AFTERNOON...AND SUBSTANTIAL CONVECTIVE INHIBITION LIKELY TO PERSIST OVER MUCH OF THE KS/OK/TX WARM SECTOR...CONVECTIVE INITIATION APPEARS UNLIKELY. OF THE FEW MODEL FORECASTS THAT DO SHOW CONVECTIVE PRECIPITATION OR EXPLICIT STORMS...THE MEAN BOUNDARY LAYER DEWPOINTS AS HIGH AS 66 F LOOK TO BE TOO HIGH COMPARED TO REGIONAL OBSERVATIONS. IF A STORM FORMS...THE ENVIRONMENT WILL FAVOR SUPERCELLS WITH AN ATTENDANT RISK FOR AT LEAST LARGE HAIL...BUT THIS RISK REMAINS HIGHLY CONDITIONAL. THE MORE PROBABLE AREA FOR CONVECTIVE INITIATION THIS AFTERNOON/EVENING WILL BE ACROSS ERN CO ON THE NW EDGE OF THE RICHER LOW-LEVEL MOISTURE...AND NW OF THE STRONGER CAP. THE INITIAL HIGH-BASED CONVECTION WILL LIKELY FORM IN THE DEEPLY MIXED ENVIRONMENT ACROSS ERN CO BY ABOUT 21-22Z...AND THEN STORMS WILL PROGRESS ENEWD INTO PROGRESSIVELY MORE FAVORABLE MOISTURE AND VERTICAL SHEAR PROFILES ACROSS W/NW KS BY THIS EVENING. HOWEVER...THE NEWD ADVANCE OF THE WARMER EML WILL ALSO OCCUR THIS EVENING...RESULTING IN A RATHER RAPID INCREASE IN CONVECTIVE INHIBITION NEAR AND AFTER SUNSET ACROSS WRN KS. THUS...THE WINDOW OF OPPORTUNITY FOR TORNADOES COULD BE RATHER LIMITED IN TIME/SPACE. OTHERWISE...ANY STORMS THAT SURVIVE EWD INTO WRN KS THIS EVENING WILL BE CAPABLE OF PRODUCING AT LEAST ISOLATED VERY LARGE HAIL. ...AZ RIM COUNTRY TO FOUR CORNERS THIS AFTERNOON... A STRONG BAND OF ASCENT IN THE LEFT EXIT REGION OF THE MID-UPPER JET...AND AN ASSOCIATED COLD FRONT...WILL CROSS NRN AZ AND THE FOUR CORNERS REGION THROUGH THIS AFTERNOON. THOUGH MOISTURE IS SOMEWHAT LIMITED...THE STRONG ASCENT AND STEEP LAPSE RATES WILL SUPPORT A BAND OF CONVECTION ACROSS THIS AREA. THE STEEP LAPSE RATES AND STRONG DEEP-LAYER SWLY FLOW WILL SUPPORT A RISK FOR ISOLATED STRONG/DAMAGING GUSTS. ...INDIANA TO OH/NW PA/WRN NY THROUGH THIS EVENING... A PRONOUNCED SHORTWAVE TROUGH IS MOVING ENEWD OVER NRN INDIANA/SW LOWER MI...AND WILL CONTINUE OVER THE LOWER GREAT LAKES TONIGHT WITH AN ACCOMPANYING SURFACE CYCLONE. THE PRIMARY LIMITING FACTOR FOR DEEP CONVECTION AND ANY SEVERE THREAT WILL BE THE QUALITY OF THE LOW-LEVEL MOISTURE. 15Z OBSERVATIONS SHOW PRIMARILY UPPER 40S DEW POINTS ACROSS OH...AS OPPOSED TO LOWER 50S SHOWN IN THE 12Z NAM FORECASTS FOR THE SAME TIME. THE PHASING OF LOW-LEVEL MOISTURE WITH THE ZONE OF ASCENT IS ALREADY POOR...AND ANY DELAY IN LOW-LEVEL MOISTENING WILL FURTHER LIMIT WHAT IS ALREADY EXPECTED TO BE MINIMAL BUOYANCY. WILL MAINTAIN LOW WIND PROBABILITIES INTO PART OF THIS AREA...BUT THE WIND DAMAGE RISK IS MARGINAL AT BEST. ..THOMPSON/MOSIER.. 04/08/2013
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_1630.html
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