121
FXUS63 KILX 122319
AFDILX

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

.KEY MESSAGES...

- While significant drought alleviation is not expected, rain is
  in the forecast for central and southeast Illinois by next
  weekend.

&&

.SHORT TERM...(Tonight through Monday)
Issued at 219 PM CDT Sun Oct 12 2025

18z/1pm surface analysis shows a 988mb low over southern Manitoba
with a cold front extending southward into the Plains. As this
front pushes slowly eastward, it will intercept limited Gulf moisture
to produce a band of clouds and scattered light showers west of
the Mississippi River tonight. Forecast soundings initially show
a very dry environment across central Illinois:however, as the
boundary nears and the profile moistens from the top-down, clouds
will increase/lower across the western KILX CWA after midnight.
Several CAMs show weak radar reflectivity spilling into the
Illinois River Valley before daybreak. Given the very dry boundary
layer, think it will take some time before any precip is able to
reach the ground. Based on NAM/RAP soundings, have opted to add
isolated showers to the forecast along/west of the Illinois River
between 06z/1am and 11z/6am. As the band of very light showers
shifts further eastward over the parched soils of central
Illinois, the precip will gradually dissipate by mid-morning. Have
included slight chance PoPs as far east as I-55 between 12z/7am
and 15z/10am, but think the showers will dry up thereafter. Any
rainfall that occurs will be quite light, amounting to only a
couple hundredths of an inch at best. The remainder of the day
will feature partly to mostly cloudy conditions west of
I-55...with mostly sunny skies further E/SE. Low temperatures
tonight will range from the middle 40s near the Indiana border to
the upper 50s west of the Illinois River. Highs on Monday will
climb into the middle to upper 70s.

Barnes

.LONG TERM...(Tuesday through Next Sunday)
Issued at 219 PM CDT Sun Oct 12 2025

A mostly uneventful work week lies ahead as central Illinois
remains under the influence of prevailing upper-level ridging.
After a slight cool-down into the lower to middle 70s on
Wednesday, readings will climb back into the upper 70s and lower
80s by Friday. After that, the weather gets a bit more interesting
as a cut-off low progged to form over northern California on
Monday gradually opens and lifts northeastward by the end of the
week. As this process unfolds, deep-layer southwesterly flow will
develop ahead of the feature across the Plains/Midwest. This will
help pull better moisture into the region and result in a more
significant chance for rainfall from Friday night through Sunday.
The big question is of course how much rain will occur. Synoptic
models often handle antecedent dry soil conditions quite poorly,
so raw QPF from any model at this point should be taken with a
grain of salt. In addition, there are still some minor timing
discrepancies among the various solutions...so it is still to
early to pinpoint exact numbers. With that said, general consensus
suggests showers and perhaps a few thunderstorms pushing into the
Illinois River Valley late Friday night...with a re-development
of showers/storms mainly east of I-55 Saturday afternoon/evening.
It therefore appears reasonable to surmise that the most substantial
rainfall will materialize Saturday afternoon across the far E/SE
CWA. The 12z NBM supports this general theory...showing a 40-50%
chance of greater than 0.50 rainfall east of I-55...and around a
30% chance of over 1 inch south of I-70. This scenario may change
slightly over the next few days, so please refer to later
forecasts for further details.

Barnes

&&

.AVIATION...  (For the 00z TAFs through 00z Monday Evening)
Issued at 612 PM CDT Sun Oct 12 2025

Clouds will increase and lower tonight ahead of a cold front. VFR
conditions are still anticipated to persist through this TAF
period, though ceilings could fall to 4-6 kft by or shortly after
12z Monday, particularly for our western terminals (KPIA, KSPI,
KBMI). The lower ceilings will be accompanied by vicinity showers,
and we have elected to maintain mention of such at KPIA, and
added mention at KSPI and KBMI given trends in short-term
guidance.

Low-level winds will maintain a gentle southeasterly component
overnight into Monday, backing east by the end of the period.


MJA

&&

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

$$