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Mesoscale Discussion 1277
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   Mesoscale Discussion 1277
   NWS Storm Prediction Center Norman OK
   0220 PM CDT Mon Jul 10 2017

   Areas affected...Southwest and Central Montana

   Concerning...Severe potential...Watch possible 

   Valid 101920Z - 102115Z

   Probability of Watch Issuance...40 percent

   SUMMARY...Thunderstorms producing locally strong winds and large
   hail are possible across southwest and central Montana later this
   afternoon and evening.  A severe weather watch is possible in the
   next 1-3 hours as thunderstorms organize over higher terrain in
   advance of an upper level disturbance.

   DISCUSSION...Thunderstorms continue to develop and organize ahead of
   an upper-level shortwave which is lifting northeastward from Idaho. 
   The risk area is characterized by MUCAPE around 2000 J/kg with
   effective deep-layer-shear of 35-45 kts, and steep low-level lapse
   rates supporting damaging winds as storms organize and move
   northeastward.  Damaging winds are the primary threat in the
   northern half of the area, with CAMS suggesting growth of a
   low-level meso-high to further support damaging wind potential. 
   Storms characterized by mid-level rotation and an increased risk of
   large hail will be more common along the southern periphery of any
   organized wind producing system.  Hail model estimates based on
   RAP-based short-term forecasts suggest maximum hail sizes of 1.5
   inches in diameter.

   ..Schneider/Darrow.. 07/10/2017

   ...Please see for graphic product...


   LAT...LON   44981368 45481397 45961390 46431337 46731263 47031140
               47351030 47580943 47680878 47640807 47320759 47000728
               46460701 45740705 45230801 45010893 44611064 44341181
               44441302 44981368 

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