Storm Prediction Center Mesoscale Discussion 1379

   Mesoscale Discussion 1379
   NWS Storm Prediction Center Norman OK
   0655 PM CDT Sat Jun 22 2024

   Areas affected...West-central into northeast Illinois

   Concerning...Severe potential...Watch likely 

   Valid 222355Z - 230200Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Some increase in severe threat is expected for western and
   northern portions of Illinois. Damaging winds are the expected main
   hazard, but a conditional tornado threat will also exist. A watch is
   likely this evening.

   DISCUSSION...Some increase in severe potential can be expected
   across portions of western into northern Illinois this evening.
   Activity currently in Wisconsin near the surface low/warm front may
   eventually congeal and push farther southward into Illinois.
   Additionally, storms along the cold front may move in from the west.
   The current expectation is that activity will generally be more
   linear in terms of storm mode with primarily a threat of damaging
   winds. While 850 mb winds are expected to modestly increase this
   evening, the low-level shear vector orientation will not be overly
   favorable for QLCS circulations. It is possible some discrete
   elements could develop ahead of the front/convective line which
   would pose a marginally greater tornado risk. Another uncertainty is
   the low-level moisture with eastward extent. Current surface
   observations show a dry pocket in the Chicagoland vicinity. Some
   higher dewpoints do exist to the southwest and should make some
   attempt to advect northeastward tonight, but the exact magnitude of
   moisture return is uncertain.

   ..Wendt/Gleason.. 06/22/2024

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

   ATTN...WFO...LOT...ILX...DVN...

   LAT...LON   41878951 42338894 42418810 41938776 41138817 40129011
               40179072 40359096 40759096 41409014 41878951