598
FXUS63 KLOT 170701
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
201 AM CDT Tue Sep 17 2024

.KEY MESSAGES...

- Hot and dry conditions will continue through at least
  Thursday.

- Chances for rain will return to the area on Friday and through
  the weekend.

&&

.DISCUSSION...
Issued at 201 AM CDT Tue Sep 17 2024

Through Monday:

Over the next 72 hours, an upper-level trough diving southeastward
along the coast of British Columbia will "kick and replace" a trough
currently over central California toward the northern Plains.
Meanwhile, an upper-level low currently centered over the Carolinas
will gradually weaken while drifting eastward toward the Atlantic
Coast. Inbetween both large-scale features, the local weather
pattern in our neck of the woods will remain remarkably banal with a
persistence methodology remaining appropriate. Today through
Thursday will feature mostly sunny skies, low humidity levels, light
winds, and daily lake breezes. Highs will top off in the mid to
upper 80s each afternoon (cooler near the Lake Michigan shoreline),
and overnight lows will fall into the mid to upper 50s each
night. A few patches of ground fog may develop around daybreak
each morning in northeastern IL, as well (where locally higher
dew points off Lake Michigan should be somewhat "sheltered"
from the easterly advection of drier air elsewhere).

Thursday night into Friday, low-level humidity will begin to
increase as a remnant warm sector from an occluding cyclone moving
into Manitoba "sloshes" eastward into the Great Lakes. A few showers
and storms may develop along a weakening cold front overnight across
parts of Iowa and Wisconsin, though they should be in a weakening
state by the time they reach northwestern Illinois by daybreak
Friday. With forecast soundings depicting minimal capping by mid-
afternoon, a few showers or storms cannot be ruled out before
sunset, though coverage should be isolated given a dearth of large-
scale forcing (20% or lower chance areawide). In all, Friday is
looking relatively quiet with partly cloudy skies and highs in
the mid to upper 80s.

This weekend and beyond, EPS/GEFS guidance continue to depict a
pattern changes characterized by a return of regular chances for
showers and thunderstorms as well as gradually decreasing daily
temperatures.

Borchardt

&&

.AVIATION /06Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 1230 AM CDT Tue Sep 17 2024

No significant forecast concerns through the period. Light east
winds will likely become calm for many locations early this
morning then increase into the 5-8kt range mid/late morning. A
lake breeze will move through the Chicago terminals this
afternoon with speeds likely around 10kts. Easterly winds will
diminish to 5kts or less this evening, possibly becoming light
and variable by early Wednesday morning.

Some shallow ground fog or patchy fog may develop early this
morning and again late Tuesday night into Wednesday morning.
Favored areas for early this morning appear to be across far
northeast IL into southeast WI. Not expecting anything
widespread nor at the terminals. cms

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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