Sep 5, 2011 1300 UTC Day 1 Convective Outlook
Updated: Mon Sep 5 13:01:08 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20110905 1300 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20110905 1300 UTC Day 1 Tornado Probabilities Graphic
Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Probabilistic Damaging Wind Graphic
20110905 1300 UTC Day 1 Damaging Wind Probabilities Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point.
Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Probabilistic Large Hail Graphic
20110905 1300 UTC Day 1 Large Hail Probabilities Graphic
Probability of hail 1" or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
   SPC AC 051257
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0757 AM CDT MON SEP 05 2011
   
   VALID 051300Z - 061200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF AL AND GA...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK
   AREA...FROM ERN MS ENE INTO THE CAROLINAS...
   
   ...SYNOPSIS...
   SHORTWAVE TROUGH NOW DROPPING SE ACROSS THE LWR MS VLY WILL CONTINUE
   TO INTERACT WITH REMNANTS OF T.S. LEE TODAY/TNGT...WITH THE COMBINED
   CIRCULATION CENTER LIKELY EVOLVING INTO AN ELONGATED CLOSED LOW OVER
   THE MS/AL BORDER BY 12Z TUE.  AT THE SAME TIME...SEPARATE...MORE
   STRONGLY AMPLIFIED SHORTWAVE IMPULSE NOW OVER THE CNTRL GRT LKS
   SHOULD CONTINUE E TO THE LWR LKS/NRN NEW ENGLAND BY EARLY TUE AS
   BROAD RIDGE PERSISTS OVER THE RCKYS.
   
   AT LWR LVLS...REMNANT SFC CIRCULATION CENTER OF LEE...NOW OVER FAR
   SRN MS...IS EXPECTED TO TRACK SLOWLY NEWD...REACHING CNTRL AL THIS
   EVE AND NRN GA BY 12Z TUE.
   
   ...SERN STATES TODAY/TNGT...
   SHOWERS/TSTMS SHOULD INCREASE IN COVERAGE AND STRENGTH OVER PARTS OF
   AL AND GA LATER TODAY AS MODEST SFC HEATING BOOSTS SBCAPE TO BETWEEN
   1000 AND 2000 J/KG IN WARM SECTOR OF REMNANT T.D. LEE.  CONTINUED
   EXTRATROPICAL TRANSITION OF THE SYSTEM THAT ALREADY WAS OF HYBRID
   ORIGIN WILL STRENGTHEN AND POSSIBLY BROADEN ASSOCIATED SSWLY
   LLJ...WITH SPEEDS INCREASING TO AOA 50 KTS.  AT THE SAME
   TIME...700-500 MB FLOW WILL INCREASE TO 50-60 KTS AS UPR CIRCULATION
   BEGINS TO ELONGATE.
   
   LOW LVL CONVERGENCE MAY FOCUS IN SEVERAL AREAS INCLUDING /1/ ALONG
   NWD-MOVING CSTL BOUNDARY NOW OVER SRN AL AND THE FL PANHANDLE.../2/
   ALONG DEVELOPING N/S CONFLUENCE ZONE NOW ALONG THE MS-AL
   BORDER...AND /3/ ALONG AXIS OF LOW LVL FRONTOGENESIS EXTENDING
   WSW-ENE ACROSS NRN PARTS OF AL AND GA.  EACH OF THESE AXES MAY SERVE
   TO CONCENTRATE STORM/SHOWER DEVELOPMENT...WITH MOIST LOW LVL
   ENVIRONMENT AND MODERATE TO LOCALLY STRONG LOW LVL DIRECTIONAL SHEAR
   FOSTERING SPORADIC EPISODES OF MESOCYCLONES AND POSSIBLE TORNADOES.
   THE GREATEST TORNADO THREAT MAY DEVELOP ALONG AND N OF THE CSTL
   BOUNDARY LATER THIS MORNING THROUGH LATE THIS AFTN...WHERE THE
   LARGEST LOW LVL HODOGRAPHS WILL COINCIDE WITH AXIS OF GREATEST
   BOUNDARY LAYER MOISTURE.  SCTD SMALL BOWS WITH LOCALLY DMGG WIND
   ALSO MAY OCCUR.
   
   LATER TODAY...AND CONTINUING TNGT THROUGH EARLY TUE...EMBEDDED
   ROTATING STRUCTURES/LEWPS MAY POSE A THREAT FOR MORE ISOLD TORNADOES
   AND LOCALLY DMGG WIND GUSTS ALONG THE AFOREMENTIONED FRONTOGENETIC
   ZONE AS THAT FEATURE DEVELOPS ENEWD FROM NRN GA INTO WRN AND CNTRL
   PARTS OF THE CAROLINAS.
   
   ...MID-ATLANTIC TO SRN NEW ENGLAND THIS AFTN...
   THE STRONGEST LARGE SCALE FORCING FOR ASCENT AND SHEAR WITH GRT LKS
   TROUGH WILL LAG ASSOCIATED COLD FRONT SETTLING SE ACROSS THE MID
   ATLANTIC AND NEW ENGLAND STATES TODAY...RESULTING IN AN ANA-TYPE
   FRONTAL SETUP.  COUPLED WITH WIDESPREAD EXISTING  CONVECTION/CLOUD
   COVER AND DIMINISHED SFC HEATING...PROSPECTS FOR
   APPRECIABLE SVR ACTIVITY APPEAR LOW.  NEVERTHELESS...POTENTIAL WILL
   EXIST FOR A FEW POCKETS OF SUFFICIENT DESTABILIZATION TO SUPPORT
   ISOLD STRONG TO LOCALLY SVR WIND GUSTS...ESPECIALLY ALONG THE
   IMMEDIATE CST FROM NJ TO ME.
   
   ..CORFIDI/GARNER.. 09/05/2011
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z