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Mesoscale Discussion 1248
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   Mesoscale Discussion 1248
   NWS Storm Prediction Center Norman OK
   0504 PM CDT Thu Jul 06 2017

   Areas affected...portions of northern and central WI...western Upper
   Peninsula of MI

   Concerning...Severe potential...Watch possible 

   Valid 062204Z - 070000Z

   Probability of Watch Issuance...40 percent

   SUMMARY...Thunderstorms will likely intensify this afternoon while
   moving southeast across the western Lake Superior vicinity and into
   adjacent portions of WI and MI.  Uncertainty remains how
   thunderstorms will evolve and the overall strength/coverage of
   strong to severe storm activity.

   DISCUSSION...Visible satellite imagery shows a cumulus field
   beginning to develop across north-central WI east-southeast to the
   south of the Door Peninsula.  Thunderstorms from early-day
   convection have moved east towards Lake Huron but outflow from this
   activity spread across northern WI into the western Upper Peninsula.
   The region within the influence of the outflow is most evident in
   both the lack of vigorous cumulus growth and drier low levels with
   surface dewpoints in the upper 50s to lower 60s degrees F.  

   Veered boundary-layer flow (reference deep westerly flow from KDLH
   and KGRB) has contributed to a lack of strong low-level convergence.
   Nonetheless, strengthening winds with height (40-60 kt in the 4-8 km
   layer per KDLH VAD data) will act to organize updrafts.  It appears
   the strongest storms will move southeast along the outflow/buoyancy
   gradient located from near ASX to GRB.  Isolated large hail and
   isolated to scattered gusts (50-65 mph) capable of wind damage, are
   possible this evening.  Convective trends will be monitored for the
   possibility of a severe thunderstorm watch.

   ..Smith/Hart.. 07/06/2017

   ...Please see for graphic product...


   LAT...LON   45579143 46099137 46569063 46838937 45548722 44998710
               43828766 43768897 45579143 

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