Severe Weather Outbreak Forecast Wednesday (Updated 415 pm CDT)

Bismarck Weather Story

PUBLIC SEVERE WEATHER OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   0729 AM CDT WED JUL 08 2009
  
   ...SEVERE THUNDERSTORMS EXPECTED OVER PARTS OF THE NORTHERN PLAINS
   LATE AFTERNOON THROUGH TONIGHT...
  
   THE NWS STORM PREDICTION CENTER IN NORMAN OK IS FORECASTING THE
   DEVELOPMENT OF WIDESPREAD DAMAGING WINDS OVER PARTS OF THE NORTHERN
   PLAINS LATE AFTERNOON THROUGH TONIGHT.
  
   THE AREAS MOST LIKELY TO EXPERIENCE THIS ACTIVITY INCLUDE
  
          CENTRAL AND SOUTHERN NORTH DAKOTA
          MUCH OF SOUTH DAKOTA
  
   ELSEWHERE...SEVERE STORMS ALSO ARE POSSIBLE FROM EASTERN MONTANA
   ACROSS THE REMAINDER OF THE NORTHERN PLAINS THIS AFTERNOON AND
   EVENING...AND SOUTHEASTWARD ACROSS PARTS OF THE LOWER MISSOURI
   VALLEY REGION OVERNIGHT.
  
   A MIDDLE-UPPER LEVEL TROUGH IS EXPECTED TO MOVE FROM THE PACIFIC
   NORTHWEST ACROSS THE NORTHERN HIGH PLAINS THIS AFTERNOON AND
   EVENING.  MEANWHILE A RELATED COLD FRONT SHOULD PROGRESS EASTWARD
   ACROSS THE DAKOTAS INTO A PROGRESSIVELY MORE MOIST AND UNSTABLE AIR
   MASS.  THUNDERSTORM POTENTIAL WILL REMAIN SUPPRESSED MOST OF THIS
   AFTERNOON BY A STRONG CAPPING INVERSION OF WARM AIR ABOVE GROUND
   LEVEL.  NONETHELESS...BECAUSE OF THE FAVORABLE LEVELS OF
   MOISTURE...INSTABILITY...LIFT AND WIND SHEAR...WE EXPECT THIS CAP TO
   BREAK OVER PARTS OF THE NORTHERN HIGH PLAINS AND DAKOTAS...PERHAPS
   AS EARLY AS LATE AFTERNOON. 
  
   SUPERCELLS WITH LARGE HAIL...SEVERE THUNDERSTORM WIND AND A FEW
   TORNADOES ARE POSSIBLE AT FIRST.  THEN...SEVERE STORMS SHOULD GET
   MORE NUMEROUS THIS EVENING...GROWING INTO A COMPLEX WITH POTENTIAL
   FOR A WIDESPREAD AND LONG-LASTING THUNDERSTORM WIND DAMAGE EVENT
   KNOWN AS A DERECHO.  THE GREATEST THREAT AREA APPEARS TO BE OVER
   PARTS OF THE DAKOTAS.  FOR MORE METEOROLOGICAL DETAILS PLEASE SEE
   THE SPC CONVECTIVE DAY-1 OUTLOOK...WHICH IS BEING UPGRADED TO
   WIND-BASED MDT RISK TO REFLECT THE THREAT.
  
   STATE AND LOCAL EMERGENCY MANAGERS ARE MONITORING THIS DEVELOPING
   SITUATION. THOSE IN THE THREATENED AREA ARE URGED TO REVIEW SEVERE
   WEATHER SAFETY RULES AND TO LISTEN TO RADIO...TELEVISION...AND NOAA
   WEATHER RADIO FOR POSSIBLE WATCHES...WARNINGS...AND STATEMENTS LATER
   TODAY.



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