343
FXUS63 KILX 050741
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
241 AM CDT Fri Sep 5 2025

.KEY MESSAGES...

- A cold front will pass through this morning, helping to promote
  breezy west winds (25-30 mph) and a hint of smoke. Temperatures
  will then remain on the cool side through Sunday with daily
  highs near 70 F and overnight lows in the 40s.

- Warmer and continued dry weather is anticipated through much of
  next week.

&&

.DISCUSSION...
Issued at 237 AM CDT Fri Sep 5 2025

A deep, vertically-stacked, upper-level low remains anchored over
Ontario this morning, with an embedded lobe of 500-mb vorticity
pivoting across the Great Lakes. At the surface, an occluded
surface low and its attendant cold front are sweeping across our
region.

Impacts from this morning`s frontal passage will be limited. A
narrow and transient band of FGEN behind the front is the only
chance for rain today, though it appears too modest to provide any
beneficial precipitation. Winds behind the front will become
breezy, with occasional gusts between 25-30 mph, as the influx of
dry air and dewpoints in the 40s promote deeper boundary layer
mixing.

There is also a fair amount of wildfire smoke wrapping into the
upper-level trough, which currently envelops the eastern half of
the US. This was evident yesterday afternoon in the CIRA Geocolor
(RGB) satellite channel. The 00z HRRR near-surface smoke prognosis
from yesterday evening shows a narrow stripe of medium/low
concentration pushing across central and southeast Illinois by
daybreak, coinciding with the cold front. If boundary layer mixing
deepens more than currently modeled, which often occurs in dry
air masses, near-surface smoke concentrations could be higher than
what the HRRR depicts.

Persistent troughing will continue to bring below-normal
temperatures through Sunday night. Daily highs will be near 70,
with overnight lows in the 40s. While a few additional jet streaks
and embedded shortwave troughs will pivot around the upper-level
low this weekend, the dry air mass should thwart measurable
precipitation.

By Monday, the upper low will open and lift into the Atlantic,
leading to a pattern shift as a pronounced ridge builds across the
central US. This change will bring a warming trend, with low-
level winds becoming southerly on the backside of departing
surface high pressure. Current NBM guidance suggests daily highs
will warm into the low-to-mid 80s by the middle of next week, and
we see no reason to deviate from this forecast.

There is some semblance of a backdoor cold front sagging into our
area by next Thursday or Friday. However, the blocking pattern
along the Gulf coast looks like it might become reinforced,
limiting moisture return and thus, rain chances.

MJA

&&

.AVIATION...  (For the 06z TAFs through 06z Friday Night)
Issued at 1221 AM CDT Fri Sep 5 2025

A cold front is entering west-central IL late tonight, which will
bring a period of unsettled weather to the area through Friday.
Winds will veer from south-southwest to west-northwest by mid
morning with gusts up to 25 kts common through the afternoon. A few
showers will develop behind the front, though these will be high
based and are not expected to impact ceilings or visibility. Winds
should ease by Friday evening as speeds fall below 10 kts.

NMA

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$