Decatur, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

736
FXUS63 KILX 151049
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
549 AM CDT Wed Oct 15 2025

.KEY MESSAGES...

- Seasonably warm and mostly dry weather sticks around through
  Friday.

-  Widespread showers and thunderstorms are expected late Friday
   night through Saturday night. This will bring beneficial
   rainfall as well as a threat for severe weather on Saturday
   near and south of I-72.

&&

.DISCUSSION...
Issued at 228 AM CDT Wed Oct 15 2025

Surface high pressure is centered over the western Great Lakes
Region early this morning with ridging extending south of there
through a good portion of the central US. An ill defined
cold/stationary front remains draped over the area, which will keep
cloud cover persistent for most through tonight. Radar mosaic shows
isolated to scattered shower activity ongoing over north-central
parts of the state where weak upper forcing ripples through an upper
ridge aloft. Although better chances for rain will stay north of
here, a few brief showers (<15% chance) may clip areas near and
north of I-74 today. Seasonably warm and mostly dry weather will
continue through the end of the week with a pattern change coming by
the weekend.

A strong upper low positioned over the southwest US this morning
will eject into the Northern Plains Thursday night, sending an
attendant surface low toward the Hudson Bay by the weekend. A
trailing cold front will work through central Illinois sometime on
Saturday, bringing beneficial rainfall and perhaps some strong to
severe storms. Somewhat better agreement amongst models shows the
front approaching west-central parts of the state by midday, which
would favor moderate instability building out ahead of the front by
Saturday afternoon (up to 1000 J/kg) in a strongly sheared
environment (0-6 km over 50 kt). If these parameters are realized,
we could see strong to severe storms develop Saturday afternoon and
evening, especially near/south of I-72 where SPC has a 15% risk.
Beneficial and at times heavy rainfall is also expected with the
weekend storms. Climatologically high PWATS exceeding 1.5" and mean
flow nearly parallel to the front would support training
thunderstorms capable of high rainfall rates. Rainfall
probabilities have come up a bit with a 30-50% chance for 1" or
more areawide and about a 10-20% chance of over 2" (highest in
southeast IL). Shower activity may linger into Sunday as lapse
rates steepen in breezy northwest flow behind the front.

Temperatures cool back near seasonal normals behind the weekend
system, with highs through early next week topping out in the 60s to
near 70 degrees. Additional chances for rain are possible by the
middle of next week under a more progressive upper pattern.

NMA

&&

.AVIATION...  (For the 12z TAFs through 12z Thursday Morning)
Issued at 549 AM CDT Wed Oct 15 2025

Persistent cloud cover continues as several weak upper
disturbances interact with a stationary front. Ceilings will
fluctuate some with bases ranging from 5-9k ft. Although better
chances for precipitation will stay north of the airfields, there
is a low chance (<15%) for an isolated shower at northern
terminals later this morning/afternoon. Winds will generally be
out of the east-northeast with speeds at 10 kts or less.

NMA

&&

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

$$