963
FXUS63 KILX 180445
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1045 PM CST Mon Nov 17 2025

.KEY MESSAGES...

- Rain will spread west to east across the area this evening into
  tonight, with a few showers lingering through tomorrow. Most
  locations will see rain amounts between a tenth and half an inch.

- Marginal risk (level 1 of 5) for severe weather for areas along
  and south of I-72 (east of Springfield) tomorrow. Main hazard
  will be large hail with elevated storms, but there is a 2%
  tornado risk in the southeastern IL counties.

- The next opportunity for beneficial rainfall and strong storms
  arrives Thursday into Friday. There is a 30-60% chance (highest
  south) for rain amounts greater than 1 inch.

&&

.UPDATE...
Issued at 836 PM CST Mon Nov 17 2025

Water vapor imagery late this evening shows an upper low over the
central Plains states. Strong warm air advection out ahead of the
low has sparked the development of showers and storms, with an arch
of precipitation stretched from roughly Peoria southeastward toward
Effingham just after 8 pm. A 40-45 kt LLJ will nose into central
Illinois later tonight, which will continue to support
shower/storm activity through the overnight hours. MUCAPE is
forecast to increase as dewpoints rise, peaking between 500-1000
J/kg overnight. However, forecast soundings show a strong
inversion with long, skinny CAPE profiles which would favor less
intense updrafts. Despite this, a few stronger storms cannot be
ruled out with the main hazard being heavy rain and small hail.

NMA

&&

.DISCUSSION...
Issued at 217 PM CST Mon Nov 17 2025

The rain system is moving into Western IL this afternoon. Looks like
there could be some virga ongoing across IL this afternoon. The
showers will start to move into the area from the west-southwest
just after 00z this evening, progressing eastward. There is the
potential for some rumbles of thunder through the overnight hours,
but nothing severe. Most of the forecast area should be dry by 18z
tomorrow, but there is the potential for redevelopment starting at
18z. This redevelopment will bring the risk for severe weather. We
could see up to half an inch of rain from this system, with higher
amounts locally with any stronger thunderstorms.

The SPC has introduced a marginal risk (level 1 of 5) for severe
weather for areas along and south of I-72 (east of Springfield).
There is 2% tornado risk for for our southeast six counties (south
of I-70), and a 5% hail risk for the entire outlooked area. It looks
like, based off the HREF, the best MUCAPE values can be found
tomorrow afternoon in southeastern IL (1000-1500 J/kg), with 0-6 km
shear values of 70-75 knots. LCLs are pretty low tomorrow as well.
There may be a small cap that the parcels would have to bust
through, as many forecast soundings are showing a stable layer in
the lowest 1 km. Otherwise, these storms would be elevated, which is
what is influencing the 5% hail risk. The freezing level is around
3km based off the forecast soundings. The further south you get, the
higher the chance storms could be surface based, which would allow
for the 2% tornado risk.

Wednesday would be a brief break in the rain as there is a lull
between systems. Early Thursday morning, another low pressure system
will pass through central and southeastern IL, bringing additional
showers and thunderstorms. The temperatures should remain above
freezing, keeping the precipitation type liquid. This system is
looking to pack more of a punch with the rainfall amounts. From
Thursday morning to Saturday morning, QPF of 1-1.5 inches is in the
forecast. A warm front may lift up into southeastern IL with this
low pressure system, which could bring some strong storms. Reading
the SPC discussion for Day 4 (Thursday), they are hinting at the
need for severe probabilities that day, but still too uncertain to
put anything out yet.

Temperatures stay near or just above normal for the next week. The
warmest day this week is Thursday with highs in the 60s and lows in
the upper 40s to low 50s , thanks to the warm front that will lift
northward. Behind the low pressure system Friday, temperatures will
drop back down to near normal.

Copple

&&

.AVIATION...  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1045 PM CST Mon Nov 17 2025

An approaching weather system will bring an active stretch of
weather over the next 24 hours. Shower and isolated storm
activity will continue through the overnight hours, though there
may be brief breaks at times. Low stratus arrives Tuesday morning
and sticks around through the remainder of the period. Ceilings
look to largely remain MVFR, though occasional drops to IFR are
possible. 10-15 kt southeast winds will become light and back to
the northeast as the surface low passes through Tuesday
afternoon.

Another round of thunderstorms will develop in east-central
Illinois during the late afternoon hours. Added PROB30 groups at
KDEC and KCMI, though this will likely need to be modified as
things become clearer.

NMA

&&

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

$$