DAY ONE CONVECTIVE OUT LOOK PAY ATTN TO THE GREAT LAKES ON THIS ONE SPC AC 301630 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1130 AM CDT FRI AUG 30 2013 VALID 301630Z - 311200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE WRN DAKOTAS AND VICINITY... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE SRN UPPER GREAT LAKES/UPPER MIDWEST AREA... ...SYNOPSIS... A LARGE MID- AND UPPER-LEVEL RIDGE WHICH HAS PREVAILED ACROSS A LARGE PORTION OF THE U.S. FOR SEVERAL DAYS WILL PERSIST...THOUGH SOME FLATTENING OF THE RIDGE ON ITS NRN PERIPHERY AND SOME EROSION ON ITS ERN FRINGE IS EXPECTED THIS PERIOD -- RESULTING IN A MODEST/SLOW SWWD SUPPRESSION OF THE FEATURE. THE FLATTENING ON THE NRN PERIPHERY OF THE RIDGE IS OCCURRING AS A SERIES OF SHORT-WAVE TROUGHS EMBEDDED WITHIN AN ENHANCED BELT OF WLY FLOW PROGRESS REPETITIVELY EWD ACROSS THE NRN U.S. AND ADJACENT SRN CANADA. MEANWHILE...AS THESE FEATURES CREST THE RIDGE AND DROP SEWD...SOME WWD EXPANSION OF A WEAK MEAN TROUGH OVER THE WRN ATLANTIC WILL AID IN THE AFOREMENTIONED EROSION ON THE ERN EDGE OF THE LARGE-SCALE RIDGE. MORE IMPORTANTLY...THE REPETITIVE PASSAGE OF THESE SHORT-WAVE FEATURES IN AN ANTICYCLONIC ARC AROUND THE PERIPHERY OF THE RIDGE WILL CONTRIBUTE TO ONGOING CONVECTIVE/SEVERE POTENTIAL ACROSS N CENTRAL PORTIONS OF THE COUNTRY THROUGH THE PERIOD. ...WRN DAKOTAS VICINITY... A PAIR OF WEAK UPPER FEATURES CROSSING THE NRN INTERMOUNTAIN REGION ATTM -- THE STRONGEST OF WHICH NOW ENTERING NWRN MT -- WILL MAINTAIN WEAK LARGE-SCALE ASCENT ACROSS MT AND INTO THE NRN HIGH PLAINS AREA THIS AFTERNOON. WHILE MODEST CAPE IS FORECAST ACROSS MT GIVEN LIMITED LOW-LEVEL MOISTURE...GREATER DESTABILIZATION IS PROGGED TO CONTINUE ACROSS THE HIGH PLAINS VICINITY AND INTO NEB...ALONG TRAILING PORTIONS OF A WEAK COLD FRONT WHICH HAS BACKED WWD INTO THIS AREA. WITH WEAK SLY FLOW MAINTAINING LOW 60S DEWPOINTS...CONTINUED HEATING WILL YIELD 1000 TO 2000 J/KG MIXED-LAYER CAPE. THOUGH ISOLATED STORMS ARE FORECAST TO DEVELOP ACROSS MT -- WHICH MAY POSE ISOLATED WIND POTENTIAL...MORE WIDESPREAD DEVELOPMENT IS EXPECTED WITHIN THE MORE FAVORABLE AIRMASS ACROSS THE HIGH PLAINS. AS STORMS DEVELOP IN THIS AREA...35 TO 45 KT MID-LEVEL WLYS WILL CONTRIBUTE TO SHEAR SUPPORTIVE OF ORGANIZED STORMS/ISOLATED SUPERCELLS. THE STRONGEST CONVECTION WILL BE CAPABLE OF PRODUCING LARGE HAIL AND LOCALLY DAMAGING WINDS INTO THE EVENING HOURS -- SUPPORTING A CONTINUATION OF THE SLIGHT RISK FORECAST OVER THIS REGION. ...SRN UPPER GREAT LAKES/UPPER MIDWEST REGION... A WEAK COLD FRONT EXTENDING FROM THE UPPER GREAT LAKES REGION WSWWD INTO THE MID MO VALLEY WILL CONTINUE TO MOVE SLOWLY SEWD THIS PERIOD...AS UPPER DISTURBANCES CREST THE DOMINANT RIDGE. WITH A MOIST/HEATING BOUNDARY LAYER ALONG AND AHEAD OF THE FRONT BECOMING INCREASINGLY FAVORABLE FOR CONVECTIVE DEVELOPMENT...EXPECT ONGOING STORMS ACROSS NRN LOWER MI TO INCREASE...EXPANDING SWWD ALONG THE FRONT ACROSS LOWER WI AND INTO IA BY AFTERNOON -- ALONG WITH AN ASSOCIATED INCREASE IN STORM INTENSITY WITH TIME. THOUGH DEEP-LAYER FLOW WILL REMAIN SOMEWHAT MODEST -- WITH ONLY 25 KT LOWER AND MID-TROPOSPHERIC WNWLYS ACROSS THE REGION...SHEAR WILL BE SUFFICIENT IN CONJUNCTION WITH ANTICIPATED MODERATE DESTABILIZATION TO SUPPORT SOME SEVERE RISK WITHIN STRONGER CELLS/CONVECTIVE CLUSTERS. GIVEN EXPECTED DESTABILIZATION AND HI-RES CONVECTION-ALLOWING MODELS ALL SUPPORTING THE AFOREMENTIONED SCENARIO...UPGRADE TO 15% HAIL AND WIND PROBABILITY/SLIGHT RISK FORECAST APPEARS WARRANTED FOR THE EXPECTED AFTERNOON/EVENING MAXIMUM IN CONVECTIVE INTENSITY. ..GOSS.. 08/30/2013 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z CURRENT UTC TIME: 1925Z (3:25PM), RELOAD THIS PAGE TO UPDATE THE TIME
Posted on: Fri, 30 Aug 2013 19:27:12 +0000
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