Wednesday, August 5, 2015

Severe Thunderstorms Possible Star Valley later Wednesday

The Storm Prediction Center in Norman OK has forecast the potential for a few severe thunderstorms to move across southeastern Idaho into Western Wyoming, including Star Valley later this afternoon.

Following are the associated graphics with the forecast.

Severe Weather Forecast for August 5 2015
Damaging wind Potential









Following is the meteorological reasoning for the forecast


   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1129 AM CDT WED AUG 05 2015

   VALID 051630Z - 061200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF ID/WY/MT...

   ...THERE IS A SLGT RISK OF SVR TSTMS OVER NORTHERN AR...

   ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE NORTHERN
   PLAINS AND NORTHERN ROCKIES...

   ...THERE IS A MRGL RISK OF SVR TSTMS FROM OK INTO THE TN VALLEY...

   ...THERE IS A MRGL RISK OF SVR TSTMS OVER PARTS OF NEW ENGLAND...

   ...SUMMARY...
   A FEW SEVERE STORMS WITH GUSTY WINDS AND HAIL WILL BE POSSIBLE OVER
   PARTS OF ARKANSAS THIS AFTERNOON.  OTHER STRONG TO SEVERE STORMS
   WITH HAIL AND WIND MAY OCCUR OVER PARTS OF THE NORTHERN ROCKIES AND
   INTO THE NORTHERN PLAINS...AND A COUPLE OF STRONGER CELLS POSSIBLY
   CAPABLE OF PRODUCING MARGINALLY SEVERE HAIL MAY AFFECT PARTS OF
   NORTHERN NEW ENGLAND.

   ...MID MS VALLEY...
   A REMNANT MCS IS TRACKING SOUTHEASTWARD ACROSS PARTS OF
   AR/OK/MO...AND WILL MOVE ACROSS MUCH OF NORTHERN/CENTRAL AR TODAY. 
   STRONG HEATING IS OCCURRING AHEAD OF THE CONVECTION...WHERE
   DEWPOINTS ARE IN THE MID 70S AND AFTERNOON MLCAPE VALUES OF
   1500-2500 J/KG ARE EXPECTED.  STORMS MAY RE-INTENSIFY ALONG THE
   LEADING EDGE OF THE MCS LATER TODAY...POSING A RISK OF DAMAGING WIND
   GUSTS AND HAIL.  THUNDERSTORMS WILL LIKELY ALSO DEVELOP EASTWARD
   FROM THE MCS ACROSS PARTS OF TN/KY THIS AFTERNOON...BUT WILL BE MORE
   DISORGANIZED AND TRANSIENT.  NEVERTHELESS...THE STRONGEST CELLS WILL
   BE CAPABLE OF DOWNBURST WINDS AND HAIL.

   ...NORTHERN ROCKIES INTO ID...
   WATER VAPOR LOOPS SHOW AN IMPRESSIVE SHORTWAVE TROUGH OVER NORTHERN
   NV.  THIS FEATURE WILL TRACK ACROSS ID/UT THIS AFTERNOON...PROVIDING
   LIFT AND FOCUS FOR SCATTERED THUNDERSTORMS.  MODELS ARE IN AGREEMENT
   THAT CONVECTION WILL FORM OVER SOUTH-CENTRAL ID BY MID/LATE
   AFTERNOON AND TRACK NORTHEASTWARD ALONG THE EASTERN SNAKE RIVER
   VALLEY...EVENTUALLY INTO NORTHWEST WY.  SUFFICIENT INSTABILITY AND
   STRONG WINDS ALOFT...COUPLED WITH STEEPENING LOW LEVEL LAPSE RATES
   WILL PROMOTE A RISK OF DAMAGING WINDS WITH THESE STORMS.  GIVEN
   CONSISTENCY IN MODEL SOLUTIONS AND FAVORABLE ORIENTATION OF FORCING
   WITH TERRAIN...HAVE OPTED TO UPGRADE REGION TO SLGT RISK.

   ..HART/PICCA.. 08/05/2015

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