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 121956
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0256 PM CDT MON SEP 12 2011
   
   VALID 122000Z - 131200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE ARROWHEAD OF MN
   THROUGH THE UPPER PENINSULA OF MI AND NRN WI...
   
   ...GREAT LAKES AREA...
   
   NO SIGNIFICANT CHANGES TO ONGOING FORECAST. STORMS ARE EXPECTED TO
   INCREASE WITH AS DEEPER ASCENT ATTENDING A PROGRESSIVE SHORTWAVE
   TROUGH AND ITS ATTENDANT COLD FRONT MOVE THROUGH THE UPPER PENINSULA
   OF MI AND NRN WI LATE THIS AFTERNOON INTO THE EVENING. MODERATE
   INSTABILITY...30-40 KT EFFECTIVE SHEAR AND STEEP LAPSE RATES WILL
   PROMOTE A THREAT OF ISOLATED DAMAGING WIND AND HAIL.
   
   ..DIAL.. 09/12/2011
   
   .PREV DISCUSSION... /ISSUED 1058 AM CDT MON SEP 12 2011/
   
   ...MI/WI...
   MORNING SATELLITE LOOPS SHOW A WELL-DEFINED MID LEVEL SHORTWAVE
   TROUGH MOVING ACROSS MANITOBA/ND.  THIS FEATURE WILL TRACK ACROSS
   THE UPPER GREAT LAKES THIS AFTERNOON AND EVENING SUPPORTING A RISK
   OF SCATTERED THUNDERSTORMS.  ACTIVITY IS LIKELY TO FORM NEAR THE
   ASSOCIATED SURFACE COLD FRONT AS IT MOVES ACROSS LAKE SUPERIOR AND
   WESTERN UPPER MI LATER TODAY.  FAVORABLE DEEP LAYER VERTICAL SHEAR
   AND SUFFICIENT CAPE WILL PROMOTE ORGANIZED MULTICELL AND SUPERCELL
   STRUCTURES CAPABLE OF LARGE HAIL AND DAMAGING WINDS.  VEERED LOW
   LEVEL WINDS AND SOMEWHAT LIMITED LOW LEVEL MOISTURE SHOULD LESSEN
   THE TORNADO RISK.  STORMS WILL THEN TRACK EAST-SOUTHEASTWARD ACROSS
   MUCH OF UPPER MI AND APPROACH NORTHERN LOWER MI THIS EVENING. 
   UNCERTAINTY ALSO EXISTS HOW FAR SOUTHWEST STORMS MAY DEVELOP ALONG
   THE FRONT INTO WI.  GIVEN TRENDS IN NEW NAM SOLUTION AND SOME OF THE
   MESOSCALE MODELS...HAVE EXTENDED SLIGHT RISK AREA INTO CENTRAL WI TO
   ACCOUNT FOR THIS THREAT.
   
   ...AZ...
   SOUTHWEST FLOW ALOFT REMAINS OVER AZ TODAY WITH A PLUME OF MORE RICH
   MID LEVEL MOISTURE EVIDENT IN MORNING SATELLITE IMAGERY.  INCREASED
   CLOUDS AND WEAKER LAPSE RATES SHOULD LIMIT THE OVERALL THREAT OF
   SEVERE STORMS TODAY.  HOWEVER...LOCALLY GUSTY/DAMAGING WINDS CANNOT
   BE RULED OUT THIS AFTERNOON IN STORMS THAT FORM OVER THE CENTRAL AZ
   WHERE STEEP LOW LEVEL LAPSE RATES WILL BE PRESENT.
   
   ...CAROLINAS...
   A SHORTWAVE TROUGH IS MOVING ACROSS GA/SC AT THIS TIME...AND SHOULD
   HELP TO PROMOTE SCATTERED AFTERNOON THUNDERSTORMS ALONG THE NC/SC
   COAST.  LOW LEVEL WINDS ARE WEAK AND LAPSE RATES ARE POOR. 
   NEVERTHELESS...A FEW OF THE STRONGER STORMS MAY PRODUCE LOCALLY
   GUSTY WINDS AND HAIL BEFORE MOVING OFFSHORE.
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z