Mesoscale Discussion 1496
   NWS Storm Prediction Center Norman OK
   0538 AM CDT Thu Aug 12 2021

   Areas affected...Southern Lower MI

   Concerning...Severe potential...Watch unlikely 

   Valid 121038Z - 121215Z

   Probability of Watch Issuance...20 percent

   SUMMARY...Damaging wind gusts are possible across south-central and
   southeast Lower MI over the next hour or so.

   DISCUSSION...Convective cluster moving northeastward across southern
   Lower MI recently produced a severe gust of 51 kt at Coldwater MI
   (OEB). Velocity signatures from IWX and DTX show this an area of
   enhanced outbounds well at around 5 and 6 kft, respectively. The
   cluster itself has also surged forward, with recent storm motion
   estimated at around 55 kt. The downstream air mass is very moist,
   with relatively minimal temperature-dewpoint spreads, suggesting
   these gusts are not driven by negative buoyancy but likely the
   manifestation of a strong downdraft reaching the surface and/or
   downward momentum transfer from the low-level jet. Given the
   reduction in buoyancy with northeastward extent, it is likely that
   this downburst will eventually surge ahead as the storm gusts out.
   However, low-level vertical shear is strong enough for localized
   downdraft/vertical shear balance to persist for an hour or so. As a
   result, damaging wind gusts are possible across south-central and
   southeast Lower MI for the next hour. Limited spatial and temporal
   extent of the threat will likely preclude the need for watch.

   ..Mosier/Edwards.. 08/12/2021

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

   ATTN...WFO...CLE...DTX...IWX...GRR...

   LAT...LON   42208489 42518436 42778302 42378279 41788319 41668412
               41678486 42208489