516
FXUS63 KLOT 120043
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
743 PM CDT Sat Oct 11 2025

.KEY MESSAGES...

- Other than the potential for a few light showers late Tuesday
  (20-30% chance), mainly dry and seasonable conditions are
  expected the next several days.

- The pattern turns more active late next week with increasing
  rain chances (30-40%).

&&

.UPDATE...
Issued at 743 PM CDT Sat Oct 11 2025

Minor forecast updates this evening, primarily to increase the
footprint of mostly cloudy skies across northeast IL. Lake-
induced stratus and stratocu continues to move west off of Lake
Michigan this evening, spreading inland past the Fox River
Valley. Clouds may approach the I-39 corridor later in the
evening, before gradually veering low-level winds shift the bulk
of the cloud cover toward the IL/WI border area and allowing
some decrease in coverage across the heart of the metro
overnight. Have beefed up cloud cover across northeast/parts
of north central IL based on Satellite and high- res guidance
trends overnight. Otherwise, no significant changes made.

Ratzer

&&

.DISCUSSION...
Issued at 300 PM CDT Sat Oct 11 2025

The quiescent weather pattern continues today with the local
area on the southwest periphery of broad surface high pressure.
Aloft, the upper ridge axis has also shifted east into the
region with the two closed lows meander well to our east and
southeast along the east coast. Some lake effect clouds paired
with onshore flow have held down temperatures in the low to mid
60s across much of the Chicago metro this afternoon, with
farther inland areas still managing to warm into the upper 60s
to lower 70s.

Winds take on a southeasterly direction on Sunday which should
help temperatures warm up a bit more than seen today with highs
in the low to mid 70s for much of the area. While the lake
remains quite warm (temps in the 60s), locales along the
immediate lakeshore in Illinois may still only remain mainly in
the mid-upper 60s for highs as a reinforcing lake breeze pushes
inland in the afternoon.

A strong upper level short wave is progged to lift across the
northern Plains into Ontario Sunday night into Monday. An
associated surface cold front may lead to increased shower
development west of the area. The effective front stalls out
prior to reaching our area as well, though a few elevated light
showers/sprinkles may drift into northwest Illinois prior to
dissipating Monday morning. Monday looks like the warmest day of
the several days with highs in the 70s areawide.

Winds eventually flop northeasterly on Tuesday (due to a
combination of a frontal passage / lake breeze / influence of
the surface high). This may be paired with a few showers late in
the day into the evening, though confidence remains generally
low and overall favors very light amounts if it does occur.

Dry weather then likely continues midweek as upper level ridging
builds back across the region paired with expanding surface
high pressure. However, ensemble guidance continues to trend
toward a more active patter returning for the end of next week
with increasing shower chances Friday into Saturday (30-40%).
Something to keep an eye on over the coming days.

Petr

&&

.AVIATION /00Z TAFS THROUGH 06Z MONDAY/...
Issued at 633 PM CDT Sat Oct 11 2025

Patchy MVFR stratocu off of Lake Michigan is the only aviation
forecast concern this evening.

Surface high pressure centered northeast of the Great Lakes
region will continue to drift off to the east tonight into
Sunday. This will result in a gradual shift in modest low level
winds from ENE to ESE/SE through the period. This will maintain
onshore flow off of Lake Michigan which will continue to push
fairly extensive lake-induced cloud cover across the IL
terminals tonight, though this should eventually lift largely
north and northwest of the terminals during the predawn hours.
Bases had dipped into MVFR range off the lake late this
afternoon, though latest trends are for cigs to have lifted
back into VFR range for the most part. Can`t rule out some
additional patches of 2500-3000 foot bases this evening, but
thinking is that VFR should prevail.

FEW/SCT VFR cu possible Sunday, with winds generally ESE to SE
around 10 kts. Will likely see winds come a little more easterly
in the afternoon (ENE at GYY) for the Chicago sites with the
diurnal lake-enhancement.

Ratzer

&&

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

&&

$$

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