776
FXUS63 KILX 121732
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1232 PM CDT Sun Oct 12 2025

.KEY MESSAGES...

- Drought conditions will continue this week, as the probability
  of appreciable rain through at least Thursday is low.

- There is a higher (30-50%) chance for beneficial rainfall late
  Friday into Saturday.

&&

.DISCUSSION...
Issued at 124 AM CDT Sun Oct 12 2025

***** LOW CHANCE OF APPRECIABLE RAINFALL THROUGH THURSDAY *****

Latest RAP mesoanalysis reveals 500mb heights around 5800m across
central IL, which is solidly under the influence of a positively
tilted upper level ridge extending out of the Southern Plains. This
will serve to keep the area dry and mostly clear today, resulting in
a large (~30 degF) diurnal temperature swing with afternoon highs
ranging from the mid 70s north of I-74 to around 80 west of a
Galesburg to Effingham line.

The ridge will be flattened and shift east a little tonight into
tomorrow as a weak disturbance attempts to push into the Prairie
State. The CAMs are virtually all depicting some light showers
across west-central IL overnight, but the dry low level airmass will
be difficult to overcome with forecast soundings indicating
saturation doesn`t reach the surface. While thick cloud cover and
virga will be most common we can`t rule out a localized (light)
shower, so sprinkles were added to the forecast west of roughly I-55.

Tomorrow into early Wednesday, we once again remain too close to the
ridge`s northern periphery to guarantee dry weather as one or more
unorganized pieces of energy ripple through the Midwest. NBM
advertises the highest rain chances (10-20%) north of the I-72
corridor Tuesday evening into Wednesday morning, but even locations
that see precipitation will only receive amounts too light to
improve the drought.

Temperatures will remain seasonably mild with highs in the mid to
upper 70s Monday and Tuesday, low 70s Wednesday, and low to mid 70s
Thursday.


***** RAIN CHANCES INCREASE GOING INTO THE WEEKEND *****

Uncertainty increases in the appreciable weather as model forecasts
for the upper level pattern diverge Friday and beyond. The primary
source of uncertainty still surrounds precisely when the ridge
breaks down as troughing developing in the West shifts east, but
there`s some ensemble spread in the amplitude of the pattern as
well. It is certainly something to watch, as multiple iterations
of the deterministic global models have advertised a strong autumn
storm system developing in the left exit region of a jet streak
emerging across the Plains or Midwest, but we will hold off on
attempting to nail down forecast details given the spread. For
perspective, the 00z GFS brings the low through central Wisconsin,
the 12z ECMWF deepens it rapidly as it lifts through Illinois
into Indiana and Michigan, and the 00z CMC places it as far north
as the Hudson Bay with just a trailing cold front moving through
central/southeast IL. The good news is that all of these solutions
and about 50-70% of the LREF grand ensemble membership give the
area measurable precip, and given the potential for stronger
moisture transport with these systems there are some solutions
giving us appreciable amounts. The NBM, EAGLE Ensemble (GFS AI
ensemble), and ECMWF AIFS ensemble each suggest a 20-30% chance
for more than a half inch which, while not a drought buster, would
certainly be beneficial. Stay tuned to the forecast and attendant
discussion for updates.

Bumgardner

&&

.AVIATION...  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1232 PM CDT Sun Oct 12 2025

VFR conditions will prevail through the entire 18z TAF period.
Skies will initially be clear this afternoon...followed by
increasing mid/high clouds across west-central Illinois by this
evening as a cold front approaches from the west. While forecast
soundings indicate a very dry boundary layer, it appears ceilings
will lower to 5000-8000ft along/west of I-55 late tonight into
Monday morning. Several models suggest a few very light showers or
sprinkles will develop closer to the front in the Illinois River
Valley. As a result, have carried VCSH at KPIA from 13z-18z Mon.
Further east, conditions will remain dry at the other central
Illinois terminals. Winds will be from the E/SE at 5-10kt.

Barnes

&&

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

$$