Sep 12, 2005 1100 UTC Day 3 Severe Thunderstorm Outlook Updated: Mon Sep 12 06:09:37 UTC 2005
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SPC AC 120606 DAY 3 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0106 AM CDT MON SEP 12 2005 VALID 141200Z - 151200Z ...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE SCNTRL U.S.... ...SYNOPSIS... QUASI SPLIT-FLOW REGIME WILL FEATURE TWO NEARLY ZONAL MID LEVEL STREAMS ACROSS MUCH OF THE CONUS. AN EXCEPTION TO THE ZONAL FLOW PATTERN WILL EXIST OVER THE ERN GREAT LAKES AND ALONG THE EAST COAST WHERE 1) A NRN STREAM TROUGH WILL LIKELY BE LIFTING INTO SERN CANADA FROM THE GREAT LAKES AREA...AND 2) THE CIRCULATION ASSOCIATED WITH OPHELIA MAY BE MOVING NWD NEAR/OVER THE ERN SEABOARD. PRIMARY FOCUS FOR STRONG TO SEVERE TSTMS WILL BE A FRONTAL ZONE ASSOCIATED WITH THE TROUGH DEPARTING THE GREAT LAKES AREA. THE TRAILING PORTION OF THIS FRONT WILL LIE FROM THE LOWER OH VALLEY WSWWD TO THE SRN PLAINS. LOW AMPLITUDE DISTURBANCES TRAVELING WITHIN THE RELATIVELY FAST SRN STREAM FLOW WILL MOVE ATOP THE FRONT AND AID ASCENT ALONG THE BOUNDARY FROM THE SRN HIGH PLAINS...ACROSS OK...TO THE OH VALLEY. ...ERN OK/NRN AR TO THE LOWER OH VALLEY... LATEST NAM AND GFS ARE IN REASONABLY GOOD AGREEMENT IN DEPICTING THE POTENTIAL FOR AT LEAST ONE MCS DEVELOPING WITHIN THE STALLED FRONTAL ZONE ACROSS PARTS OF OK/AR. THIS COMPLEX MAY BE ONGOING AT THE END OF THE DAY 2 PERIOD AND COULD BE SUSTAINED OR REGENERATED DURING WEDNESDAY AS MID/UPPER LEVEL IMPULSES MOVE EAST IN THE FAST WLY FLOW ACROSS THE REGION. PRESENCE OF WARM/MOIST AIR AND 30-40KT WLY MID LEVEL FLOW SHOULD CONTRIBUTE TO AN ENVIRONMENT FAVORABLE FOR SEVERE STORMS. FARTHER EAST...NAM AND GFS ARE ALSO INDICATING DESTABILIZATION AHEAD OF THE FRONT FROM THE LOWER/MID MS VALLEY TO THE LOWER OH VALLEY DURING THE AFTERNOON. DESPITE SOMEWHAT WEAKER DEEP LAYER SHEAR FORECAST OVER THIS REGION...FRONTAL FORCING AND MAGNITUDE OF INSTABILITY COULD SUPPORT A FEW CLUSTERS OF MULTICELLULAR CONVECTION WITH SOME THREAT FOR HAIL AND WIND. ...MID ATLANTIC TO NY... SIGNIFICANT MODEL DIFFERENCES EXIST IN THE EVENTUAL TRACK OF OPHELIA AND THE INTERACTION OF THE TROPICAL SYSTEM WITH THE FRONT SWEEPING EAST ACROSS NY AND THE NORTHEAST LATE IN THE PERIOD. TIMING OF THE BOUNDARY INTO NY/PA OVERNIGHT WOULD SUGGEST LIMITED INSTABILITY TO SUPPORT SEVERE STORMS. HOWEVER...GFS GENERATES CONSIDERABLE UPWARD MOTION AND CONVECTIVE QPF ON THE FRONT OVER PA/NY. THIS OCCURS AS THE FRONT BEGINS TO ENCOUNTER INFLUX OF TROPICAL MOISTURE CIRCULATING INLAND WITH OPHELIA WHICH THE GFS TAKES ON A FASTER NWD TRACK ALONG THE EAST COAST. LATEST TPC TRACK DOES NOT SUPPORT THIS SCENARIO AND GIVEN LARGE MODEL DISCREPANCIES...ONLY A LOW PROBABILITY SEVERE THREAT WILL BE INTRODUCED OVER WRN/UPSTATE NY AND PARTS OF WRN PA AT THIS TIME. ..CARBIN.. 09/12/2005 ...NOTICE... THE STATION RELATIVE POINTS IN THIS PRODUCT ARE NOW AVAILABLE SEPARATELY UNDER THE WMO HEADINGS WUUS01 PTSDY1... WUUS02 PTSDY2...WUUS03 PTSDY3. THE INCLUSION OF POINTS IN THIS DISCUSSION WILL BE DISCONTINUED AFTER THE 2005 CONVECTIVE SEASON. A PUBLIC NOTIFICATION STATEMENT (PNS) WILL PROVIDE DETAILS ON THE TRANSITION. CLICK TO GET WUUS03 PTSDY3 PRODUCT NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 1100Z |