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Mesoscale Discussion 1959
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MD 1959 graphic

   Mesoscale Discussion 1959
   NWS Storm Prediction Center Norman OK
   0333 PM CDT Wed Sep 11 2019

   Areas affected...Southern Wisconsin...southern Lower Michigan

   Concerning...Severe Thunderstorm Watch 645...

   Valid 112033Z - 112230Z

   The severe weather threat for Severe Thunderstorm Watch 645
   continues.

   SUMMARY...Damaging wind gusts will continue to be a threat into the
   early evening across WW 645. Isolated large hail may occur,
   particularly with more discrete activity in southern Lower Michigan.
   Convective coverage may yet increase this evening as the front sags
   south. Potential appears low for new WW to the south of WW 645, but
   trends will continue to be monitored.

   DISCUSSION...The main area of convective activity in WW 645 is
   currently across southeastern Lower Michigan where stronger heating
   has occurred. Mid-level ascent continues to be strongest over
   southern Wisconsin, though convective coverage is more limited
   currently. By late afternoon/early evening, convergence along the
   cold front is expected to increase as the surface anticyclone in
   Ontario strengthens. This would promote further thunderstorm
   development, particularly in western portions of the Watch where
   clouds have cleared out and MLCIN has been decreasing with time.
   With primarily a linear storm mode anticipated, damaging wind gusts
   will continue to be the primary threat with much of the activity
   late this afternoon into the evening. Deep-layer shear across Lower
   Michigan should improve as the mid-level wave continues eastward.
   Given the more discrete storm mode ahead of the slowly advancing
   cold front, isolated large hail would be most likely in this area
   with stronger/rotating storms. The tornado threat, while nonzero, is
   expected to remain low and decrease as 850 mb flow veers/decreases
   with time and linear forcing for ascent increases. Southward extend
   of severe convection is uncertain given the drop-off in deep-layer
   shear. It remains possible that a few strong storms will impact
   northern Illinois/Indiana. Confidence in a new WW south of the
   current activity is low, though observational trends will continue
   to be monitored this evening.

   ..Wendt.. 09/11/2019

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

   ATTN...WFO...CLE...DTX...APX...IWX...GRR...LOT...MKX...DVN...
   ARX...

   LAT...LON   42459050 43289008 43828705 43858400 43608250 41988282
               41428357 41388418 41348454 41588793 41929000 41999027
               42189050 42459050 

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Page last modified: September 11, 2019
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