905
ACUS11 KWNS 222356
SWOMCD
SPC MCD 222355
ILZ000-230200-

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