Mesoscale Discussion on severe thunderstorm potential across a portion of the Chicago area this afternoon

Isolated severe thunderstorms with a damaging wind/hail risk may develop this Tuesday
afternoon across northern Illinois, southeastern Wisconsin, northwest Indiana and
southwestern Lower Michigan (see escalloped area on the headlined map). A Severe
Thunderstorm Watch issuance is possible this afternoon, depending upon radar trends.

Following is the National Storm Prediction Discussion….

   Mesoscale Discussion 1242
   NWS Storm Prediction Center Norman OK
   0110 PM CDT Tue Jun 25 2019

   Areas affected...Portions of southern WI...northern
   IL...northwestern IN...and southwestern Lower MI

   Concerning...Severe potential...Watch possible 

   Valid 251810Z - 252015Z

   Probability of Watch Issuance...40 percent

   DISCUSSION...A well-defined MCV that originated from convection
   earlier this morning across NE will continue moving quickly eastward
   around 40 kt along the WI/IL border this afternoon. Low-level
   airmass recovery is still underway to the east of this MCV, with the
   environment only weakly unstable. But, surface dewpoints have
   generally increased into the upper 50s and lower 60s across
   north-central/northeastern IL. Recent VWP profiles from KDVN and
   KLOT show strong westerly flow around 35-50 kt in the 2-4 km AGL
   layer in association with the MCV. There is some concern that as
   low-level lapse rates continue to steepen, some of these enhanced
   winds aloft could reach the surface if a small thunderstorm complex
   can develop. Radar imagery from 18Z shows a recent increase in
   reflectivity along the WI/IL border, and this could be the first
   attempt at the formation of a bowing segment. Isolated strong to
   damaging winds appear to be the main threat, although hail could
   occur in the strongest updrafts as mid-level lapse rates gradually
   steepen. Although watch issuance is not immediately likely, an
   increase in convective coverage/intensity may warrant a Severe
   Thunderstorm Watch at some point this afternoon.
Notice: you are using an outdated browser. Microsoft does not recommend using IE as your default browser. Some features on this website, like video and images, might not work properly. For the best experience, please upgrade your browser.