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Mesoscale Discussion 1323
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   Mesoscale Discussion 1323
   NWS Storm Prediction Center Norman OK
   0206 PM CDT Sun Jul 16 2017

   Areas affected...Central Illinois...northeastern Missouri...and far
   southeastern Iowa

   Concerning...Severe potential...Watch unlikely 

   Valid 161906Z - 162000Z

   Probability of Watch Issuance...20 percent

   SUMMARY...Convection increasing in portions of west-central Illinois
   and vicinity should remain sparse enough to preclude a WW issuance,
   although trends will be monitored into the early evening.

   DISCUSSION...A cluster of storms was gradually increasing in
   intensity across far southeastern Iowa/west-central Illinois over
   the past hour.  These storms were located along and just ahead of a
   cold front migrating southward into the northern portions of the
   discussion area.  Strong insolation has warmed low-level
   temperatures into the low 90s F beneath modestly steep mid-level
   lapse rates (around 7.5 deg C/km), resulting in strong instability. 
   Favorable deep shear profiles will favor organized updrafts, and at
   least an isolated risk for large hail and damaging wind gusts will
   exist as storms propagate southeastward through an axis of strong
   instability downstream across central Illinois.

   Despite this strong instability and well-focused low-level forcing
   for ascent (along the front), a couple of negating factors may keep
   the overall coverage of storms isolated enough to preclude a WW
   issuance, including:

   1) subtle convective inhibition (in the 700-800mb layer) and 2) a
   lack of forcing aloft, with subtle height rises/shortwave ridging
   currently located across the region.  A more substantial shortwave
   trough will migrate southeastward across the Great Lakes through the
   afternoon, but this trough may remain too far displaced from ongoing
   activity to instigate a more widespread threat.

   Convective coverage is currently expected to be a bit too sparse to
   necessitate a WW issuance at this time, although trends will
   continue to be monitored.

   ..Cook.. 07/16/2017

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

   ATTN...WFO...ILX...LSX...DVN...DMX...

   LAT...LON   40619226 40819185 40939125 40919052 40838974 40658899
               40348842 39878797 39358773 38868782 38598886 38529012
               38849130 39479201 40019228 40619226 

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Page last modified: July 16, 2017
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