748
FXUS63 KILX 161712
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1212 PM CDT Thu Oct 16 2025

.KEY MESSAGES...

- Seasonably warm weather sticks around through Friday.

- Widespread showers and thunderstorms are expected late Friday night
  through Saturday night. There is a marginal risk for severe
  storms near and east of the Illinois River on Saturday.

- Breezy northwest winds develop on Sunday with a 20-30% chance
  for gusts exceeding 40 mph.

&&

.DISCUSSION...
Issued at 247 AM CDT Thu Oct 16 2025

Water vapor imagery shows an upper ridge located over the central
CONUS with a closed upper low over the intermountain west. At the
surface, ridging from a high over the Great Lakes Region extends
south into central Illinois. Isentropic ascent at the 300 K level
has led to numerous mid-level clouds and even some showers to our
northwest atop the ridge. A few brief showers may slide into western
parts of the area this morning, though most CAMS show it missing us
to the north. Stratus will retreat northward by this afternoon as
the upper ridge starts is track eastward. Temperatures today and
tomorrow will remain seasonally warm with highs in the middle 70s to
near 80 degrees.

The weather turns unsettled heading into the weekend. A ~1004 mb
surface low presently located over eastern Colorado will lift into
the Northern Plains states this evening, then approach Hudson Bay by
Saturday as it deepens to about 985 mb. A trailing cold front will
work through central Illinois on Saturday, bringing beneficial
rainfall and the threat for strong to severe storms. The front looks
to approach west-central parts of the state by midday, which would
favor moderate instability (up to 1000 J/kg) building in a strongly
sheared environment (0-6 km over 50 kt) within the warm sector.
Strong to to severe storms are possible by Saturday afternoon and
evening, especially east of the Illinois River where SPC has a
marginal risk. Primary risks with any stronger storms would be
damaging winds gusts, but strong wind shear may support a few
rotating storms as well. Beneficial and perhaps at times heavy rain
is also expected with the weekend storms. PWATS exceeding 1.5" and
mean flow nearly parallel to the front would support training
thunderstorms capable of high rainfall rates. There is 50-60%
chance for rain amounts exceeding 1" areawide, with a 20-30%
chance to exceed 2" (highest in southeast IL).

A secondary surface low is shown developing along the cold front
heading into Sunday and rapidly deepening as it lifts into the Great
Lakes Region. Showery, wrap around precipitation looks to linger
into Sunday as lapse rates steepen beneath northwest flow aloft. In
addition, strong pressure rises on the backside of the deepening low
will lead to a quick increase in winds. Forecast soundings show the
upper end of gusts at the top of the mixed layer exceeding 40-45 kt
with mean winds up to 40 kt. Probabilities for exceeding 40 mph on
Sunday sit around 20-30% for now (EPS), but one limiting factor will
be the extensive cloud cover on the backside of the low/front. A
better handle on maximum potential wind speeds should become clearer
as more high resolution guidance becomes available in the next day
or so.

Temperatures will cool back near seasonal normals Sunday through the
new week, with highs most days in the 60s. Another stronger system
looks to bring additional rainfall to the area as early as
Tuesday.

NMA

&&

.AVIATION...  (For the 18z TAFs through 18z Friday Afternoon)
Issued at 1212 PM CDT Thu Oct 16 2025

Lingering MVFR clouds over eastern Illinois lifted to around 4000
feet by midday, and VFR conditions will prevail through Friday
morning. Main aviation concern will be with winds, as they trend
from southeast to south, then increase to 10-15 knots by mid
morning.

Geelhart

&&

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

$$