Strong thunderstorms developing Downstate-some could impact far south portions of the Chicago Metro area

Sunshine has emerged across far northern Illinois, but thunderstorms packing gusty winds and  downpours have developed across central and southern portions of the state, generally along and south of I-80. The latest mesoscale discussion  just issued by the Storm Prediction Center in Norman, Oklahoma acknowledges the potential for some strong/ severe thunderstorm development, but does not anticipate the issuance of a severe thunderstorm watch.

 Mesoscale Discussion 1055
   NWS Storm Prediction Center Norman OK
   0440 PM CDT Sat Jul 14 2018

   Areas affected...portions of southern into central IL

   Concerning...Severe potential...Watch unlikely 

   Valid 142140Z - 142315Z

   Probability of Watch Issuance...20 percent

   SUMMARY...A few strong, locally damaging wind gusts will be possible
   late this afternoon across portions of central IL. A watch is not
   expected.

   DISCUSSION...Clusters of thunderstorms have become loosely organized
   across west-central IL this afternoon. A few severe gusts have been
   noted near the St. Louis metro area over the last hour and some
   linear organization has developed further north into central IL.
   Strong heating of a very moist boundary layer has resulted in MLCAPE
   greater than 2000 J/kg across the MCD area. Modest deep layer
   effective shear around 30 kt is present and likely aiding in the
   loosely organized cluster/line segment. Furthermore, steep low level
   lapse rates and PW values approaching 2 inches could result in a wet
   microburst or two.  Eastward extent of the severe threat will be
   limited by earlier cluster of storms across east-central into
   southeast IL, which has stabilized the boundary layer. Given the
   limited area and isolated nature of the threat, a watch is not
   expected, but a few strong/locally damaging wind gusts will be
   possible.