668
FXUS63 KILX 280639
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
139 AM CDT Thu Aug 28 2025

.KEY MESSAGES...

- Seasonably cool conditions continue into early next week, with
  daily highs ranging from the mid 70s to low 80s and lows in the
  50s.

- There is a 15% chance of a light shower north of a roughly
  Lacon to Paris line through around midday.

- There is a 50-60% chance of showers and storms around the
  middle of next work week. Confidence remains low in precise
  timing and any severe weather risk.

&&

.DISCUSSION...
Issued at 134 AM CDT Thu Aug 28 2025

***** SLIGHT SHOWER CHANCES NORTHEAST THIS MORNING *****

At 130am, satellite imagery reveals an area of mid level clouds
drifting southeastward across the northern half of the Prairie
State, and regional radar mosaic shows some showers across southwest
Wisconsin and northern Illinois. Guidance suggests this region of
isentropic upglide will shift south, clipping our area mid morning
into early afternoon, ahead of a mid level shortwave trough. Given
how dry the low levels appear on forecast soundings, most of this
activity is not expected to reach the surface in our area, but did
not feel comfortable pop-free given the splotchy QPF in the HRRR and
FV3 - which are capturing the current precip well; we`ve included
around a 15% chance of showers north of a roughly Lacon to Paris
line from roughly 4am through noon. The cloud cover will keep
temperatures cooler in those areas this morning, but by mid
afternoon area- wide low 80s are expected.

The HRRR and NAMNest suggest a few more showers will develop near
the I-80 corridor this afternoon along a lake breeze off of Lake
Michigan, with a couple hundred J/kg of shallow SBCAPE apparent on
NAM and HRRR soundings there. The NAMNest threatens to bring those
into our area, clipping Marshall County, but as (1) it`s the
outlier, (2) the airmass is becoming increasingly dry by that time,
and (3) synoptic descent is favored in the wake of the shortwave
we`ve left sub-mentionable (<15%) PoPs there for now.

***** COOL AND DRY WEEKEND IN STORE *****

High res guidance suggests a back door cool front will slide in from
the northeast late tonight into tomorrow, bringing a more stable and
slightly cooler airmass to much of central IL. High temperatures
will range from the low 80s across our southwest counties to mid 70s
along and north of the I-74 corridor. Under the influence of surface
high pressure, dry and seasonably cool conditions should continue
right through the weekend with daily highs in the mid 70s to
around 80 and lows in the 50s.

***** SLIGHTLY WARMER, THUNDERSTORM CHANCES RETURN NEXT WEEK *****

Global deterministic models suggest a stronger trough will dig into
the region at some point mid next week. With a brief push of warm
advection ahead of it, temperatures will climb back towards or
slightly above normal with NBM giving a 30-50% chance for highs > 85
by next Wednesday. Along its attendant cold front, some showers and
storms can be expected, with over 70% (40-50%) of raw (calibrated)
guidance giving us measurable rainfall. The severe set up doesn`t
appear overly impressive at this point, with moisture return into
our area ahead of the system limited in duration (and following a
seasonably dry airmass). Of course, a lot can change in the forecast
between now and then; the feature is currently in the Bearing Sea,
so it has a long journey through varying airmasses before it reaches
the Midwest. Conditions turn sharply cooler and breezy behind this
system; in fact, NBM has a 30% chance for both sub 70 degree high
temperatures and wind gusts over 30 mph by next Thursday.

Bumgardner

&&

.AVIATION...  (For the 06z TAFs through 06z Thursday Night)
Issued at 1208 AM CDT Thu Aug 28 2025

VFR conditions to prevail over the next 24 hours. Ceilings
generally around 9000 feet in the KPIA-KCMI vicinity through
midday, as a weak upper disturbance brings a few showers after
12-13Z. Forecast soundings suggest this may be little more than
virga. As the disturbance passes, winds will gradually turn
westerly.

Geelhart

&&

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

$$