205
FXUS63 KILX 031053
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
553 AM CDT Wed Sep 3 2025

.KEY MESSAGES...

- A cold front will bring (80-90% chance) showers and
  thunderstorms to central IL this afternoon and evening. Severe
  weather and widespread heavy rain are not expected, but some
  localized pockets of 1-2 inches of rain is possible.

- Seasonable temperatures with highs in the low to mid 80s today,
  but well below normal temps with highs in the upper 60s to mid
  70s will be in place tomorrow through the weekend.

- There is a 15-30% chance of showers on Friday along and south of
  I-70. Rain accumulations are forecast to be unimpactful.

&&

.DISCUSSION...
Issued at 213 AM CDT Wed Sep 3 2025

Today`s the day -- the cold front we have been talking about travels
southeast across central and southeastern IL today. (Synoptics
first) Thursday will provide a brief lull before a second system
pushes into the area Friday. High pressure will set up for the
weekend into the new week. Now onto the mesoscale details...

Showers and thunderstorms are expected starting around 17z today,
working its way southeast through the remainder of the day. The
NAMNest shows the precipitation ending by 06z tonight, but the HRRR
is showing the precip lingering until 12z(ish). SBCAPE values of 500-
1000 J/kg and shear of 20-30 knots, will support thunderstorm
development, with a chance of stronger wind gusts at times. A signal
for 40-50 mph wind gusts is seen in some CAMs, but a pocket or two
of near severe winds cannot be ruled out. The forecast soundings
have a deep inverted "v" shape to them, with DCAPE values of 400-800
J/kg. The better environment for severe storms is just off to the
southwest of the forecast area. SPC stretched the marginal risk
(level 1 out of 5) just to the west of Scott County for D1.

Our QPF shows 0.25-0.5 inches for today. The HREF LPMM is showing
localized pockets around an inch being possible today, especially
where a heftier storm sets up this afternoon. This won`t bust the
drought, but it will dampen the ground a little.

Highs today will range from 75-85 degrees, cooler temperatures where
the front had already passed. Overnight temperatures will vary
widely with north of I-70 being in the mid 40s to low 50s and south
of I-70 in the mid to upper 50s as the front finishes its journey
through southeastern IL. Highs ranging in the 70s are forecast into
the new week, with Friday being the exception. On Thursday night,
lows in the mid 50s.

Friday another low pressure system will move through the Midwest
causing a decent temperature gradient during the day in central IL
from the series of fronts that will pass through. Increased WAA in
the southern half of the state will allow daytime temperatures to
get up near 80 degrees south of I-70 as a warm front pushes a brief
warm nose northward. However, CAA will be in place in the northern
half of the CWA, limiting highs to the upper 60s to low 70s. The
cold front associated with the low pressure system will be out of
the CWA by Friday evening. Overnight lows going into Saturday
morning will be quite chilly (low 40s to near 50 degrees). There is
also a 20-40% chance of showers with the frontal passage along and south
of I-70 Friday.

Temperatures will start to rebound by early next week (highs in the
upper 70s, lows in the 50s). The CPC shows 6-10 day outlook being
below normal for temperatures but above normal for the 8-14 day
outlook, so warmer temperatures may be on their way back in the long
term. Rainfall seems scarce in the extended after Friday. CPC says
near normal precip for the 6-10 and 8-14 day outlooks.

Copple

&&

.AVIATION...  (For the 12z TAFs through 12z Thursday Morning)
Issued at 553 AM CDT Wed Sep 3 2025

A cold front will move through during the 12z period. Winds will
pick up out of the SW, gusting to around 20 knots, by 15z.
Shifting to northwesterly by this evening between 00z and 04z as
the front passes each site and becoming light (~5 knots). Showers
and thunderstorms will move through each site, with the potential
for 30-40 knot wind gusts and MVFR ceilings. Outside of any
storms, VFR conditions are expected.

Copple

&&

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

$$