Categorical Graphic
Probabilistic Tornado 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
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
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 111226
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0726 AM CDT SUN SEP 11 2011
   
   VALID 111300Z - 121200Z
   
   ...NO SVR TSTM AREAS FORECAST...
   
   ...MID ATLANTIC REGION THIS AFTERNOON...
   A NRN STREAM SHORTWAVE TROUGH WILL AMPLIFY OVER THE CANADIAN PRAIRIE
   PROVINCES THROUGH TONIGHT...WHILE DOWNSTREAM HEIGHT FALLS PROMOTE
   EVOLUTION INTO AN OPEN WAVE AND EWD MOVEMENT OF THE CLOSED LOW
   CURRENTLY OVER THE OH/MS VALLEYS.  AHEAD OF THE EWD MOVING
   TROUGH...RESIDUAL BOUNDARY LAYER DEWPOINTS IN THE 60S ACROSS THE MID
   ATLANTIC REGION WILL COMBINE WITH DAYTIME HEATING TO SUPPORT MLCAPE
   VALUES APPROACHING 1500 J/KG.  A WEAK SURFACE LEE TROUGH WILL HELP
   FOCUS THUNDERSTORM DEVELOPMENT THIS AFTERNOON FROM SE PA SWD INTO MD
   ALONG THE INSTABILITY AXIS.  DEEP-LAYER SPEED SHEAR WILL BE
   SUFFICIENT FOR SOME RISK OF SUPERCELLS...THOUGH LOW-LEVEL FLOW/SHEAR
   IS EXPECTED TO REMAIN WEAK.  A FEW STORMS COULD PRODUCE MARGINALLY
   SEVERE HAIL AND STRONG OUTFLOW WINDS...BUT THE SEVERE STORM RISK
   DOES NOT APPEAR TO WARRANT A SLIGHT RISK AT THIS TIME. 
   
   ...AZ THIS AFTERNOON/EVENING...
   A CLOSED LOW WILL REMAIN QUASI-STATIONARY NEAR THE SRN CA COAST
   THROUGH THE PERIOD.  A BELT OF 30+ KT SWLY MIDLEVEL FLOW WILL BE
   MAINTAINED FARTHER TO THE E OVER AZ...ALONG WITH A PW PLUME WITH
   VALUES NEAR 1 INCH.  THUNDERSTORMS WILL AGAIN BE POSSIBLE THIS
   AFTERNOON ALONG AND S OF THE RIM WITHIN THE MOISTURE PLUME...WHERE
   WEAK-MODERATE INSTABILITY AND EFFECTIVE BULK SHEAR OF 25-30 KT WILL
   SUPPORT A FEW ORGANIZED MULTICELLS/MARGINAL SUPERCELLS WITH AN
   ATTENDANT RISK FOR STRONG GUSTS AND MARGINALLY SEVERE HAIL.
   
   ..THOMPSON/HURLBUT.. 09/11/2011
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z