Categorical Graphic
Probabilistic Graphic
Probability of severe weather within 25 miles of a point. Hatched Area: 10% or greater probability of significant severe within 25 miles of a point.

   SPC AC 180557
   
   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1257 AM CDT TUE OCT 18 2011
   
   VALID 191200Z - 201200Z
   
   ...NO TSTM AREAS FORECAST...
   
   ...SYNOPSIS...
   WHILE A SHORT-WAVE TROUGH IS PROGGED TO MOVE INLAND OVER THE WRN
   U.S. AND THEN WEAKEN AS IT ENCOUNTERS A SHARP RIDGE OVER THE
   ROCKIES...THE MAIN FEATURE THIS PERIOD WILL BE THE VERY
   LARGE/HIGH-AMPLITUDE ERN NOAM TROUGH.  THIS TROUGH/LOW -- INITIALLY
   CENTERED INVOF THE MS VALLEY -- IS FORECAST TO DRIFT SLOWLY
   EWD/NEWD...REACHING THE UPPER OH VALLEY REGION BY THE END OF THE
   PERIOD.
   
   AT THE SURFACE...SUBSTANTIAL DISAGREEMENT CONTINUES TO EXIST AMONGST
   VARIOUS MODELS...WITH THE NAM STILL MAINTAINING A MUCH MORE INLAND
   TRACK OF THE PRIMARY LOW -- SHIFTING IT NWD ACROSS THE CAROLINAS AND
   VIRGINIA AND EVENTUALLY CONSOLIDATING WITH A WEAKER LOW AND
   OCCLUDING WWD INTO THE LK ERIE VICINITY BY THE END OF THE PERIOD. 
   MEANWHILE...THE GFS -- WHILE ENDING UP WITH THE SAME OCCLUDED-TYPE
   LOW OVER THE LK ERIE VICINITY AT THE END OF THE PERIOD -- KEEPS ITS
   MORE EASTERN LOW NOT ONSHORE OVER NC/VA DURING THE DAY BUT INSTEAD
   MOVING NWD ALONG/JUST OFF THE COAST OVER THE GULF STREAM.  
   
   ...COASTAL NC AND SERN VA...
   SEVERE THREAT ACROSS THE COASTAL CAROLINAS/MID-ATLANTIC REGION THIS
   PERIOD DEPENDS UPON THE ACTUAL SURFACE LOW TRACK -- AND RESULTING
   LOCATION OF THE PRIMARY SURFACE BAROCLINIC ZONE.  ATTM...GFS
   SOLUTION REMAINS FAVORED...WITH A TRACK OF THE SURFACE LOW ALONG OR
   JUST OFF THE COAST -- AIDED BY THE ADDITIONAL BAROCLINICITY PROVIDED
   BY THE GULF STREAM -- SEEMING MOST REASONABLE.  
   
   PRESUMING A MORE GFS-LIKE SURFACE EVOLUTION...LITTLE INLAND SEVERE
   THREAT IS EVIDENT.  WILL MAINTAIN LOW-PROBABILITY WIND AND/OR
   ISOLATED TORNADO THREAT ALONG THE NC COAST AND INTO SERN VA --
   MAINLY FOR EARLY IN THE PERIOD...BUT POSSIBLY INTO AFTERNOON SHOULD
   A MORE WWD NAM-TYPE EVOLUTION OCCUR.  HOWEVER...WILL REFRAIN FROM
   INCLUDING ANY SEVERE PROBABILITY FARTHER INLAND PER NAM FORECASTS --
   WHICH COULD KEEP VERY LOW-END TORNADO POTENTIAL AS FAR NW AS ERN PA
   INTO THE EVENING.
   
   ...S FL...
   LINGERING FRONT ACROSS S FL WILL SUPPORT POTENTIAL FOR CONVECTION
   OVER THE SRN PENINSULA.  WHILE TIMING OF THE THREAT DIFFERS AMONG
   THE MODELS -- AGAIN DUE TO SURFACE PATTERN EVOLUTION...EXPECT
   THUNDERSTORMS TO MOVE OFFSHORE DURING THE AFTERNOON.  
   
   UNTIL THEN...SHEAR WILL BE SUPPORTIVE OF ORGANIZED/SEVERE
   STORMS...AND WHILE INSTABILITY SHOULD REMAIN LIMITED DUE TO ONGOING
   PRECIPITATION/CLOUD COVER...LOW-PROBABILITY HAIL/WIND POTENTIAL IS
   EVIDENT.
   
   ..GOSS.. 10/18/2011
   
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   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z