Sep 12, 2005 1100 UTC Day 3 Severe Thunderstorm Outlook
Updated: Mon Sep 12 06:09:37 UTC 2005
Categorical Graphic
20050912 1100 UTC Day 3 Outlook Graphic
Probabilistic Graphic
20050912 1100 UTC Day Probabilitic Graphic
   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