113
FXUS63 KILX 040504
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1204 AM CDT Sat Oct 4 2025

.KEY MESSAGES...

- Widely scattered (10-15% coverage) showers will continue through
  this afternoon across areas mainly near the I-72 corridor.

- South winds gusting over 20 mph both Saturday and Sunday
  afternoons will combine with low RH values (25-35%) to increase
  fire danger. Burning is discouraged and caution is urged with
  outdoor equipment.

- Scattered showers and storms Monday into Tuesday will result in
  a 20-30% chance of a wetting rain.

&&

.DISCUSSION...
Issued at 152 PM CDT Fri Oct 3 2025

***** SLIGHT SHOWER CHANCES THROUGH THIS EVENING *****

Early Friday afternoon, central and southeast IL finds itself on the
northeast periphery of a positively tilted ridge extending across
the Great Plains. A piece of weak shortwave energy cresting the
ridge today has sparked a couple showers and even thunderstorms
amidst 500-1000 J/kg MLCAPE, and given the surface based nature of
this activity there`s no reason to suspect it will dissipate before
the loss of surface heating this evening. Slight (15%) chance PoPs
were expanded accordingly.

Around 1:30pm, we received a report of pair of landspout tornados
with one of these cells in east-central IL, and the non-supercell
tornado parameter is 0.5 to 1 for much of the region given the steep
low level lapse rates. We`d like to stress that these tend to be
brief, weak, and rarely cause damage; given their fickle nature and
absence of any precursor signatures on radar which would allow us to
issue a warning, we`ve highlighted the risk for one/two additional
landspouts via a special weather statement.

***** WARM AND DRY WEEKEND IN STORE *****

Tomorrow into Sunday, the aforementioned ridge will shift east while
a deep upper level low lifts across the Great Basin and into the
Northern Plains. In response, surface pressure will lower over the
Great Plains, causing a tightening gradient over the Plains and
Midwest. While it will be much breezier further west, we`ll still
have southerly wind gusts to 20-25 mph tomorrow and 25-30 mph on
Sunday; in fact, NBM gives a 50-70% chance peak gusts exceed 30 mph
on Sunday west of roughly I-57. Given the combination of low
afternoon RH values in the mid 20s to low 30s and low (5-8%) 10h
fuel moisture values, these seasonably gusty winds will foster
marginal fire weather conditions - not enough to warrant a Red Flag
Warning, but enough that we`d continue to urge caution with outdoor
equipment (or anything else that might generate a spark), and
discourage burning in accordance with local burn bans. Otherwise,
expect seasonably warm conditions through Monday with daily highs in
the mid to upper 80s - just a handful of degrees shy of record
values.

***** SHOWERS AND STORMS, COOLDOWN NEXT WORK WEEK *****

The upper level trough will lift into the Canadian Prairies by
Monday, and as a consequence the trailing cold front across the
Midwest will weaken and slow in its southern advance. Global
deterministic models are not yet in agreement as to the timing of
the front, with the ECMWF dropping it into the area Tuesday morning
but the GFS holding off until late Tuesday night into Wednesday
morning. Flow in the cloud-bearing layer will be roughly parallel to
the front (i.e., west-east), which could favor multiple rounds of
showers and perhaps a few thunderstorms Monday into Tuesday. Both
LREF and NBM suggest a 20-40% of a wetting rain (>0.25") out of this
activity, with the highest probabilities east of roughly I-55.

Later in the week, global models and their respective ensembles
begin to diverge in the upper level pattern, with Empirical
Orthogonal Functions (EOFs) suggesting the primary source of
ensemble variability (hence low confidence) is in the
timing/position of a ridge building across the nation`s midsection.
It appears we`ll have a couple days of temperatures closer to
seasonable normal values Wednesday into Thursday when forecast highs
are in the low 70s. However, the general trend is for increasing
heights and temperatures across the Midwest as the ridge builds
northeastward by Friday (10/10) and beyond. CPC`s 6-10 and 8-14 day
outlooks suggest we`re leaning towards (40-50% chance) above normal
temperatures.

Bumgardner

&&

.AVIATION...  (For the 06z TAFs through 06z Saturday Night)
Issued at 1204 AM CDT Sat Oct 4 2025

Main aviation concern will be with increasing winds Saturday
morning, reaching 10-15 knots out of the southwest before midday.
These will ease back with loss of daytime heating, but still range
5-10 knots out of the south in the evening.

Otherwise, VFR conditions continue, with just some scattered
diurnal clouds near 6-7kft in eastern Illinois during the
afternoon.

Geelhart

&&

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

$$