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Mesoscale Discussion 1541
NWS Storm Prediction Center Norman OK
0532 PM CDT Thu Jul 21 2022

Areas affected...Far northeast IL...northern IN...southwest Lower MI

Concerning...Severe potential...Watch unlikely 

Valid 212232Z - 220100Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated strong/severe storms capable of localized wind
damage are possible into this evening. A watch is not expected at
this time.

DISCUSSION...Isolated convective development is underway across
parts of northeast IL and southern Lake Michigan ahead of a weak
surface front draped across the area. While minimal large-scale
ascent and weak surface convergence has limited convective
maintenance over land thus far, a cluster of storms with embedded
supercell structure is evolving over the southern portion of Lake
Michigan. This activity is being aided by deep/enhanced
west-southwesterly flow characterized by 25-30 kt of 0-6 km bulk
shear per regional VWP data. Over the next few hours, convection
should continue developing/spreading east-southeastward toward
southwest Lower MI and northern IN. Despite veered surface flow over
the area, the latest MDW ACARS sounding shows a moist/well-mixed
boundary layer and long/generally straight hodograph -- supportive
of loosely organized clusters and transient supercell structures
capable of localized wind damage. Given the weak large-scale ascent
and expected onset of nocturnal boundary-layer stabilization, a
watch is not expected.

..Weinman/Thompson.. 07/21/2022

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

ATTN...WFO...IWX...GRR...LOT...

LAT...LON   42438787 42458760 42288730 42148687 42268650 43118629
            43158591 42488563 41888564 41438601 41238684 41368738
            41968799 42438787