421
FXUS63 KLOT 101814
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
114 PM CDT Thu Sep 10 2026

.KEY MESSAGES...

- Quieter conditions with near to slightly above normal
  temperatures through the weekend.

&&

.DISCUSSION...
Issued at 114 PM CDT Thu Sep 10 2026

Through Sunday Night:

Ongoing rain showers are being observed south of the Kankakee
River Valley this afternoon ahead of a mid level wave that is
passing over the area. There has been an increase in shower
coverage over the area, being located under the right entrance
region of a 300 mb jet. However, lapse rates are fairly poor
with the better well of instability south of the forecast area.
A rogue lightning strike or two may occur, but confidence is
low. This mid level wave should continue to pass south and east
over the forecast area through the afternoon with chances for
showers diminishing toward sunset.

Cloud cover over the area today has help mute temperatures
slightly. Clearing behind the wave should allow for temperatures
northwest of the Fox Valley to increase quickly, but opted to
lower this afternoon`s high temperatures else by a degree or
two. As the wave exits to the east, clearer skies can be
expected through the overnight north of I-80 (with lingering
cloud cover to the south). Winds are expected to become light
and variable overnight. With better radiational cooling due to
the lack of cloud cover, there is a chance for another round of
fog to develop toward daybreak tomorrow morning. Better chances
remain north and west of Chicago`s urban core, but satellite and
observations will need to be monitored through the night for
any fog development.

Surface high pressure will build tomorrow under the influence
of a weak ridge passing overhead. Sunny conditions are expected
with light winds to provide quite an ideal weather day
tomorrow. As the ridge passes east overnight into Saturday
morning, models are projecting a very weak shortwave to pass
over Wisconsin. There is a non-zero chance that there could be
some light showers/sprinkles on Saturday morning as the wave
passes over, but models are a.) keeping the track of the wave a
little farther north in Wisconsin and into western Michigan and
b.) struggling to penetrate a drier air mass over Illinois.
Models are suggesting that the surface cold front associated
with the wave could potentially slow and wash out over I- 80 by
Sunday morning. Perhaps some light showers develop along the
front on Sunday morning, but again, the drier air and weak
forcing should limit coverage, assuming it happens at all.
Otherwise, this weekend is looking fairly pleasant. Southerly
winds on Saturday will help drive temperatures back up into the
80s. There is a little more uncertainty with temperatures on
Sunday due to the timing of the frontal passage. An early
arrival will turn winds to the northwest and usher in cooler,
more seasonable temps in the 70s. But areas ahead of the front
south of I-80 have another chance of warming back up into the
80s.

DK

Monday through Thursday:

The first half of next week continues to look like it will turn
more active as we get into more of a southwesterly flow aloft.
There will be multiple opportunities for showers and
thunderstorms Monday-Wednesday as several shortwave troughs
ripple through the southwesterly flow. It remains too early to
pinpoint timing or rainfall amounts, but there is better chances
for a transition to a generally wetter, more unsettled pattern
next week.

Izzi/DK

&&

.AVIATION /18Z TAFS THROUGH 00Z SATURDAY/...
Issued at 1243 PM CDT Thu Sep 10 2026

There are no significant aviation forecast concerns for the
terminals at this time.

Light winds and clearing skies tonight may allow for fog to
develop in some spots once again tonight into Friday morning.
Confidence remains low in the coverage of this fog and whether
it will affect any of our TAF sites, though it would primarily
be a concern for RFD, DPA, and/or GYY if it were to occur. Light
flow within a region of surface high pressure and sharpening
lake breezes both this afternoon and again tomorrow lends
lower-than-average confidence in precise wind direction trends.
That said, winds should largely remain under 10 kts with wind
directions likely to retain an easterly component through most
of the TAF period at ORD and MDW.

Ogorek

&&

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

&&

$$

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