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Mesoscale Discussion 1129
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   Mesoscale Discussion 1129
   NWS Storm Prediction Center Norman OK
   0909 PM CDT Thu Jun 22 2017

   Areas affected...Central/Northeast IA

   Concerning...Severe potential...Watch unlikely 

   Valid 230209Z - 230415Z

   Probability of Watch Issuance...20 percent

   SUMMARY...Isolated hail and damaging wind gusts are possible with
   thunderstorms along the front as it moves across IA. A generally
   limited severe threat is anticipated and a watch is not anticipated,
   but convective trends will be monitored closely.

   DISCUSSION...Thunderstorms have developed over the past hour along
   the cold front extending from CCY (in northeast IA) southwestward to
   CBF (in southwest IA). Airmass ahead of this cold front is
   characterized by dewpoints in the low 70s, which, when combined with
   steep mid-level lapse rates (i.e. around 7-7.5 deg C per km per the
   latest mesoanalysis), is supportive of moderate instability.
   Continued southeastward progress of the cold front into this airmass
   is expected to result in continued thunderstorm development along
   the cold front. This region is along the southern periphery of the
   stronger flow aloft but enough shear (i.e. effective shear around 30
   kt) exists to support some updraft organization and a supercell or
   two, particularly across northern portions of the region where the
   shear is strongest. Hail is possible with these more organized
   storms. Farther south, a more multicellular mode is anticipated with
   any hail likely a result of brief updraft intensification due to
   cell mergers. Some upscale growth into a more linear system is
   possible but the generally modest mid-level flow (and shear) are
   expected to preclude anything but occasionally damaging winds. As a
   result, a watch is not current expected but trends will be monitored
   for upscale growth and a resulting increase in the damaging wind
   threat.

   ..Mosier/Hart.. 06/23/2017

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...DVN...ARX...DMX...OAX...

   LAT...LON   41529527 42659365 43299270 43409152 42879114 41369267
               41089468 41529527 

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Page last modified: June 23, 2017
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