Walnut Point State Park Lake Illinois Weather Forecast Discussion

458
FXUS63 KILX 111728
AFDILX
Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1228 PM CDT Sat Oct 11 2025
.KEY MESSAGES...
- Patchy fog west of roughly the IL River is forecast to linger
  until 8-9am this morning.
- The probability of appreciable rain over the next week is low
  (less than 5%), resulting in continued drought conditions.
&&
.DISCUSSION...
Issued at 117 AM CDT Sat Oct 11 2025
***** PATCHY FOG THIS MORNING *****
At 1am, surface observations and nighttime microphysics satellite
revealed patches of fog near and west of roughly the IL River, where
some places received over a quarter inch of rain yesterday morning
and skies are mostly clear. Dry advection from the northeast behind
a southward sinking front gives some uncertainty regarding the
eastward extent of any fog, though a couple CAMs briefly bring
diminished visibilities as far east as roughly the I-55 corridor
between now and sunrise - after which time the fog should be eroded
by surface heating; virtually all guidance suggests that it should
be gone by 9-10am.
***** LOW PROBABILITY OF APPRECIABLE RAINFALL THIS WEEK *****
Deterministic guidance is in agreement a positively tilted ridge
will build into the region out of the Great Plains today,
maintaining dry weather through at least tomorrow night. An ill-
defined shortwave will attempt to flatten the ridge and result in
some shower activity to our west on Monday, but at this time the dry
air over our area should be too much for that activity to overcome.
Consequently, precip chances will run only 5-10% (highest west) on
Monday; in addition, any rain would be light, and hence unable to
make an impact on the drought.
All 3 global models agree that another piece of energy emerging from
the Eastern Plains will attempt to flatten the ridge Tuesday night
into Wednesday, but once again it doesn`t look to be strong enough
to overcome our resident dry airmass. Hence precip chances (highest
north) will once again remain less than 15%, and any rainfall will
be too light to offer drought relief. A stronger disturbance is then
slated to dive southeast across the Eastern Great Lakes and
Northeast on Wednesday, and while we won`t get any precip out of it
we will see some more seasonable temperatures with highs in the
upper 60s to low 70s.
Thursday and beyond, global ensembles begin to diverge in how the
pattern evolves, with Empirical Orthogonal Functions (EOFs)
indicating the greatest source of variance (and hence, uncertainty),
given by EOF1, is in how quickly a ridge building across the
nation`s midsection moves east. As that ridge builds into the
region, expect continued dry weather and warming temperatures. Some
guidance is quite warm by Friday, when the ECMWF`s Extreme Forecast
Index (EFI) features a shift of tails - suggesting the warmest 10%
of its ensemble members forecast highs above the 99th percentile of
the M-climate (or their previous forecasts over the past ~20 years
for a 5 week period centered on October 17th). NBM indicates a 30-
40% chance for highs greater than 85 degrees both Friday and
Saturday south of roughly the I-74 corridor. Once that ridge shifts
east of the area, the timing of which is again highly uncertain, the
pattern may become more active as the upper level jet stream
strengthens and becomes highly amplified.
Bumgardner
&&
.AVIATION...  (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 1227 PM CDT Sat Oct 11 2025
VFR conditions will prevail through the entire 18z TAF period.
Diurnal Cu field continues to form along/south of a KMQB to KBMI
line as per 1720z satellite imagery and latest NAM Cu-rule.
Cloud bases will initially be around 2500ft, then will rise to
3500ft in a couple of hours. Once these clouds fade away toward
sunset, clear skies will prevail through the night. Winds will
initially be E/NE at around 10kt this afternoon, then will veer to
SE by Sunday morning.
Barnes
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$

NWS ILX Office Area Forecast Discussion