ZCZC SPCSWOMCD ALL
ACUS11 KWNS 201438 
SPC MCD 201438 
MIZ000-201615-

Mesoscale Discussion 1641
NWS Storm Prediction Center Norman OK
0938 AM CDT Thu Jul 20 2023

Areas affected...Parts of lower MI

Concerning...Severe potential...Watch likely 

Valid 201438Z - 201615Z

Probability of Watch Issuance...80 percent

SUMMARY...Storm coverage and intensity is expected to increase with
time. Eventual watch issuance is likely.

DISCUSSION...Strong thunderstorms are moving into northwest lower MI
this morning, in advance of a midlevel shortwave trough currently
moving across the upper Great Lakes. While instability is not overly
strong, diurnal heating will eventually result in MLCAPE increasing
into the 1000-2000 J/kg range by early afternoon.  Favorable
large-scale ascent and sufficient deep-layer shear will support an
increase in storm coverage and intensity with time along/ahead of an
approaching cold front. 

The ongoing storm cluster may continue to spread eastward with an
increasing damaging-wind threat, while somewhat more discrete
development will be possible along its southwestward flank,
including the potential for a few supercells this afternoon with a
threat of hail, locally damaging winds, and possibly a tornado.
Watch issuance is likely by early afternoon in order to cover these
threats.

..Dean/Hart.. 07/20/2023

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

ATTN...WFO...DTX...APX...IWX...GRR...

LAT...LON   44998571 45408469 45328414 44758376 43138371 41938362
            41888636 43658647 44108615 44998571 

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