ACUS11 KWNS 042329

SWOMCD

SPC MCD 042329 

INZ000-ILZ000-MOZ000-050200-



Mesoscale Discussion 0640

NWS Storm Prediction Center Norman OK

0629 PM CDT Mon May 04 2026



Areas affected...South-central Illinois and Southern Indiana



Concerning...Severe potential...Watch possible 



Valid 042329Z - 050200Z



Probability of Watch Issuance...40 percent



SUMMARY...An isolated severe threat for large hail is expected to

continue for a few hours across south-central Illinois, and may

affect southern Indiana. The for weather watch issuance is

uncertain.



DISCUSSION...A couple cells have recently develop to the northeast

of the St. Louis metro. The activity is located along the eastern

edge of a pocket of moderate instability, where the RAP has MLCAPE

around 1000 J/kg. The storms are being supported by an area of

low-level convergence and by large-scale ascent associated with a

subtle shortwave trough, evident on water vapor imagery. The WSR-88D

VWP near St Louis has effective shear in the 30 to 40 knot range,

and the RAP shows very steep mid-level lapse rates exceeding 7.5

C/km. This should be favorable for large hail with supercells that

form. However, a capping inversion is evident over much of

southeastern Illinois and southern Indiana. Also, RAP suggests that

instability is very weak in this same area. For this reason, the

storms are expected to remain elevated, and the eastern extent of

the severe threat is uncertain.



..Broyles/Hart.. 05/04/2026



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



ATTN...WFO...LMK...IND...PAH...ILX...LSX...



LAT...LON   38058802 38218956 38489008 38859021 39299012 39638974

            39798899 39748736 39618654 39338617 38828613 38318631

            38088688 38058802 



MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH

MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN