Argyle, Illinois Weather Forecast Discussion

799
FXUS63 KLOT 251919
AFDLOT
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
219 PM CDT Thu Sep 25 2025
.KEY MESSAGES...
- Fog possible early Friday morning, especially east of I-57.
- Dry and mild to unseasonably mild weather into next week.
&&
.DISCUSSION...
Issued at 219 PM CDT Thu Sep 25 2025
Outside of some isolated lingering lake effect showers across
parts of Lake and Porter counties in IN early this afternoon, all
is quiet across the area. For the remainder of the afternoon
expect temperatures to remain in the 70s, with skies ranging from
mostly sunny across northwestern IL to partly sunny across far
eastern IL into northwestern IN. Cloud cover will then quickly
diminish this evening as a surface ridge of high pressure shifts
overhead. The combination of light winds and mainly clear skies
under this high will likely again foster fog towards daybreak
Friday morning as temperatures drop below the cross over
temperature. This looks to particularly be the case across parts
of eastern IL and northwestern IN (east of I-57), where
conditions could favor a period of more notable fog early Friday
morning.
Any early morning fog should dissipate through mid morning.
Thereafter, expect a dry and unseasonably mild day Friday, with
highs topping out in the upper 70s to the low 80s. A weak mid-
level impulse and surface cold front will shift into far northern
IL late in the day. While no precipitation is expected with this
feature, a northeasterly wind shift a push of a bit cooler
temperatures (upper 60s to the low 70s) are expected by early
Friday evening.
In spite of this weak cool frontal passage, conditions will
quickly turn unseasonably mild again for Saturday as upper-level
ridging builds into the Midwest. Accordingly, westerly winds and
mostly sunny conditions are expected to yield temperatures
topping out in the low to mid 80s Saturday afternoon. Similar
conditions are expected for Sunday, though a lake breeze is likely
to keep conditions a bit cooler near the lake.
Mid and upper-level ridging is expected to shift in across the
Great Lakes through the middle of next week as the remnants of a
tropical system move into the southeastern CONUS. This pattern
will continue to favor dry and mild weather across our region.
However, with persistent easterly surface winds, expect the
warmest temperatures (around 80) across interior sections of
northern IL, with 70s likely elsewhere.
KJB
&&
.AVIATION /18Z TAFS THROUGH 00Z SATURDAY/...
Issued at 1237 PM CDT Thu Sep 25 2025
Aviation forecast concerns including ending of lake-effect
showers early this afternoon for GYY with gradual improvement
of MVFR conditions. In addition, lake breeze passage and
easterly wind shift likely for MDW/ORD between 1930-2100Z this
afternoon.
Surface high pressure ridge from the Southern Plains into WI
will gradually shift southeast across the terminals tonight.
North-northwest surface winds generally 10 kts or less will
become light/variable at most sites overnight as this occurs,
before becoming west-southwest Friday morning. A lake breeze is
expected to shift across MDW and ORD through mid-afternoon,
with latest high-res model guidance depicting an easterly wind
shift between 19-20Z at MDW and around 21Z at ORD.
Scattered lake-effect showers currently over GYY should end
shortly, though a period of gradually improving MVFR cigs may
persist for a few hours this afternoon. Elsewhere, cloud bases
are expected to lift into VFR range by the 18Z TAF start. Skies
should clear across the region tonight, though there does
appear to be some patchy fog potential especially over
northwest IN toward morning. Can`t rule out some shallow ground
fog elsewhere as well, though conditions appear most favorable
south/southeast of GYY.
A cold front is expected to sag south into the region toward
Friday evening. Current range of guidance indicates a wind shift
could affect ORD/MDW as early as 22Z or as late as 00-01Z. This
is at or just beyond the end of the current 30 hour TAFs so have
held off with this for issuance.
Ratzer
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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NWS LOT Office Area Forecast Discussion