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Mesoscale Discussion 1057
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   Mesoscale Discussion 1057
   NWS Storm Prediction Center Norman OK
   0329 PM CDT Fri Jun 16 2017

   Areas affected...Southern MN...Northern IA...Southwest WI

   Concerning...Severe potential...Watch likely 

   Valid 162029Z - 162200Z

   Probability of Watch Issuance...80 percent

   SUMMARY...The severe thunderstorm threat is expected to increase
   late this afternoon, with a primary threat of large hail and
   damaging wind. Watch issuance is likely within the next 30 minutes.

   DISCUSSION...A recent increase in intensity has been noted within a
   region of previously weak midlevel convection across southern MN and
   far northern IA, suggesting that storms have become rooted closer to
   the surface. Substantial heating ahead of this activity has weakened
   MLCINH, and a continued increase in coverage and intensity is
   possible into late afternoon, aided by large-scale ascent ahead of a
   vort max moving through the Dakotas and modest low-level convergence
   near a surface boundary across southeast MN/western WI. 

   While low-level moisture is rather limited at this time across the
   region, some increase is possible later this afternoon into early
   this evening. Even with the modest moisture, strong heating to near
   90F in some areas has resulted in moderate destabilization, with
   MLCAPE increasing into the 1000-2000 J/kg range across the area.
   Moderate westerly midlevel flow is resulting in effective shear of
   35-45 kts for surface-based updrafts, which is sufficient for storm
   organization. With convection expected to remain largely discrete in
   the short term, a supercell or two is possible with a threat of
   large hail and locally damaging wind. With time, some upscale growth
   is possible as cold pool generation occurs, resulting in an
   increasing damaging wind threat with eastward extent into the early

   ..Dean/Hart.. 06/16/2017

   ...Please see for graphic product...


   LAT...LON   43309594 43899585 44119535 44449431 44789304 44849058
               44539020 43798977 43039051 42769160 42689229 42459419
               42489475 42579547 42859590 43309594 

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