580
FXUS63 KILX 052250
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
550 PM CDT Tue Aug 5 2025

.KEY MESSAGES...

- There is a low (20%) chance of isolated showers and
  thunderstorms this afternoon and early evening. Severe weather
  is not anticipated, but a few funnel clouds cannot be ruled out
  and isolated heavy rain could exceed an inch in a few spots.

- Dry and seasonably hot weather will stretch from Wednesday
  through the remainder of the week.

- Additional rain chances (20-40%) return by early next week.

&&

.DISCUSSION...
Issued at 234 PM CDT Tue Aug 5 2025

The weak upper level trough that has been over the region the last
couple of days continues to edge eastward today, bringing central IL
into a region less supported by weak lift, but still enough
instability and no substantial subsidence has allowed isolated
showers to to begin developing early this afternoon in east
central and southeast IL where the most supportive instability
nearing 1500 J/kg is in process of developing. Around sunset,
this activity should end, with clouds clearing expected overnight.
As skies clear overnight, winds also look to decrease as pressure
gradients that have been providing easterly winds relax. The
result will be a tendency for at least patchy fog to form
overnight, most prevalent where recent rains have fallen.

For Wednesday, upper level ridging building out of the southern
Plains into central IL will provide a substantial subsidence
inversion over central IL, keeping any precipitation from forming,
although plenty of diurnal cumulus look to build up below the
inversion during the afternoon.

Thursday through Saturday, the ridge looks to remain from the
southwest US through the southern Plains and into the lower Midwest.
There is a good chance this will keep thunderstorm activity
deflected to the north of central IL as potential MCS activity
tracks along the periphery of this ridge. However, today`s 12Z NAM
model brings one such disturbance into northern IL, tracking
through the I-74 corridor northward Thursday afternoon and
evening. Will be keeping an eye on potential for this outlier
solution. Although the GFS tracks this disturbance by to the
north, a low level jet late Thursday night develops precipitation
in the Mississippi River valley, another outlier. The next chance
for precipitation looks to arrive late Sunday or perhaps early
next week as an upper level trough moves into the north-central
U.S. and suppresses the ridge into the southeast U.S. and an
associated frontal zone approaches central IL from the NW.

Temperatures will continue to gradually climb this week as ridging
builds into the area. Expect mid 80s highs for Wednesday, followed
by around 90 Thursday through Sunday. Temperatures should trend
downward early next week as the front moves through, but timing is
uncertain and the downtrend could be delayed if the front slows
down. Seasonably typical humidity should keep heat index values
peaking in the mid to upper 90s.

37

&&

.AVIATION...  (For the 00z TAFs through 00z Wednesday Evening)
Issued at 550 PM CDT Tue Aug 5 2025

Isolated showers/sprinkles will diminish over east central IL over
the next couple hours. Then mainly clear skies tonight and
scattered diurnal cu on Wed. Light winds and high boundary layer
RH should promote patchy fog late tonight, so kept mention of TEMPO
MVFR visibility.

25

&&

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

$$