056
FXUS63 KLOT 052335
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
635 PM CDT Sun Oct 5 2025

.KEY MESSAGES...

- Stronger winds and continued dry conditions will continue to
  result in heightened fire danger and areas of blowing this
  afternoon.

- July-like warmth continues for much of the area on Monday.

- A cold front will bring rain chances and some thunderstorms
  Monday afternoon and night.

- Dry conditions and more seasonable temperatures are in store
  mid to late week.

&&

.DISCUSSION...
Issued at 241 PM CDT Sun Oct 5 2025

Elevated fire weather concerns will persist for a few more
hours this afternoon due to dry conditions and gusty southerly
winds. RH values have fallen as low as 25 percent across the
southern CWA while winds have gusted up to 30 mph across
northern Illinois. The associated Special Weather Statement for
elevated fire weather conditions remains in effect through 6pm
CDT.

A deep trough over south-central Canada will track eastward
across northern Ontario through Tuesday. An associated cold
front stretching from northern Minnesota to western Kansas will
track southeast across the area Monday into Monday night,
bringing our first notable chance of rain in nearly two weeks.
The initial chances for precip will occur with isolated mid-
level showers brushing the northwest CWA late tonight into
Monday morning. However, precip at the surface will remain
sparse and light as the showers evaporate through a rather dry
sub-cloud layer.

Poor mid-level lapse rates and diurnal mixing in the warm
sector across the southeast half of the CWA ahead of the front
will limit intensity and coverage of precip, but with the
environment expected to be mostly uncapped, could see some
attempts at isolated thunderstorm during the afternoon. Farther
northwest, low-level forcing along the front (albeit with
overall weak convergence) will provide an impetus for isolated
to scattered showers and some thunderstorms during the
afternoon. Mixing should erode MLCAPE values while mid-level dry
air induces decent entrainment of cells, but appreciable deep-
layer shear and freezing levels around 10kft will support the
potential for small hail and gusty winds with any stronger
shower/storm.

As higher low and mid-level moisture advects toward the area
this evening and especially overnight, larger scale ascent from
the right- entrance region of a slow-moving jet core will
enhance shower/rain coverage and intensity. With a modestly
strong low-level f-gen signal along the front and marginal mid-
level lapse rates above the LPL, narrow bands of heavy rain with
embedded storms are possible. The coverage of heavy rain bands
will be low, so widespread beneficial rain to partially
alleviate the growing drought does not appear likely.

After the rain ends from north to south on Tuesday, dry
conditions are favored through the remainder of the week and
potentially through next weekend as a broad, low-amplitude ridge
settles across the central CONUS. However, a moisture-starved
impulse tracking southeast across the ridge could bring a few
high based showers or sprinkles late Thursday night into Friday.
Otherwise, seasonable temperatures midweek will gradually
moderate back to above normal to well-above normal temperatures
for the weekend.

Kluber

&&

.AVIATION /00Z TAFS THROUGH 06Z TUESDAY/...
Issued at 635 PM CDT Sun Oct 5 2025

Forecast concerns include...

Chance of thunderstorms Monday afternoon into Monday evening.
Wind shift to north/northeast late Monday afternoon.
Possible mvfr cigs Monday evening.

Southerly winds will diminish under 10kts with sunset early this
evening and then turn more to the south/southwest overnight and
to the southwest Monday morning, when speeds may increase into
the 10-12kt range. A cold front is expected to move across the
area late Monday afternoon into Monday evening, shifting winds
northerly. Wind directions will likely favor north/northeast for
ORD/MDW. Still some uncertainty on timing with refinements
likely with later forecasts.

As the cold front approaches Monday afternoon, there will be a
chance for thunderstorms from late Monday afternoon through mid
mid evening Monday. If thunderstorms do occur, they may develop
right over the Chicago terminals during this time period. There
remains uncertainty for coverage, but given the potential, have
included prob thunder mention with this forecast. Scattered
showers are expected to continue through the late evening with
the potential for a period of rain into early Tuesday morning,
after the end of the new 30 hour ORD/MDW tafs. It would be
during this time that mvfr and possible ifr cigs would be most
likely to occur. Included scattered mvfr mention for mid/late
Monday evening for now. cms

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 10 PM CDT this evening for the IL
     nearshore waters.

&&

$$

Visit us at weather.gov/chicago