ZCZC SPCSWOMCD ALL ACUS11 KWNS 231952 SPC MCD 231952 MIZ000-ILZ000-WIZ000-232145- Mesoscale Discussion 0507 NWS Storm Prediction Center Norman OK 0252 PM CDT Tue Apr 23 2024 Areas affected...Northeast Illinois and southeast Wisconsin into central Lower Michigan Concerning...Severe potential...Watch unlikely Valid 231952Z - 232145Z Probability of Watch Issuance...5 percent SUMMARY...Isolated to scattered thunderstorms will continue to develop across the Great Lakes region. A few strong to severe storms are possible with small to marginally severe hail and damaging winds as the primary hazards. Coverage of severe storms should remain sufficiently limited to preclude watch issuance. DISCUSSION...Isolated to scattered thunderstorms have been ongoing over eastern WI, the Upper Peninsula of MI, and northern WI over the past several hours with multiple reports of 0.5 to 0.75 inch hail and 35-45 knot gusts noted. This convection has largely been driven by ascent along and ahead of a secondary cold frontal surge where a combination of modest diurnal warming and cold temperatures aloft is supporting MUCAPE between 250-500 J/kg. This trend is expected to continue downstream into IL/MI as the cold temperatures aloft overspread the region and mid/upper-level cloud cover slowly shifts southeast. Based on recent observations and RAP forecast soundings, around 500 J/kg MUCAPE should be feasible as surface temperatures warm into the upper 60s. Weak mid-level winds to the north of a jet streak over IL/IN/OH have limited storm longevity/organization thus far, but destabilization closer to the stronger mid-level flow may promote higher, though still somewhat meager, effective bulk shear values between 20-25 knots. This should support better storm organization with a higher potential for marginally severe hail (0.5 to 1.0 inch) and localized damaging wind gusts (most likely between 40-50 knots). Latest mesoanalysis suggests a higher buoyancy axis exists from southeast WI into west-central/northern Lower MI, so the severe threat may be maximized across this corridor in the coming hours. However, severe thunderstorm coverage should remain limited given the overall marginal kinematic environment. ..Moore/Smith.. 04/23/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DTX...APX...IWX...GRR...LOT...MKX...DVN... LAT...LON 42488950 43578801 44268639 44628527 44778397 44328368 43908355 43568358 43318386 42828463 42128642 41808735 41608809 41558865 41568906 41568926 41978954 42178960 42488950 NNNN