Decatur, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

802
FXUS63 KILX 112301
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
601 PM CDT Sat Apr 11 2026

.KEY MESSAGES...

- A stretch of warm weather is expected to begin Sunday and last
  through Friday, with daily highs in the upper 70s and lower
  80s, and even mid 80s likely on Tuesday. Gusty south to
  southwest winds, occasionally reaching 30-40 mph, will
  accompany this warm period.

- Unsettled weather is expected much of the upcoming week, with
  daily chances of showers and thunderstorms. Severe storms are
  also a risk on Tuesday and Wednesday, with Tuesday currently
  exhibits the highest probability (15-30%) of severe weather.

&&

.DISCUSSION...
Issued at 245 PM CDT Sat Apr 11 2026

The mid afternoon surface map shows 1033 mb high pressure Lake
Huron and Lake Erie and ridging into northeast IL. A warm front
extended from southwest MO into central Nebraska. Some
convection was pushing eastward into eastern and southern parts
of Iowa and northern MO while isolated convection was in eastern
MO and far sw IL into sw KY ahead of the warm front. Clouds were
increasing over central and nw IL today (cloud bases 3-6k ft
from I-55 nw) while more peaks of sunshine in eastern IL. Temps
were mostly in the low to mid 60s over much of central IL at 2
pm, but ranged from 55-60F nw of the IL river to upper 60s to
around 70F in southeast IL from I-70 south.

The latest CAMs have showers and isolated thunderstorms brushing
areas nw of the IL river late this afternoon and evening.A few
members like the ARW have very isolated convection lifting
toward sw CWA by mid to late evening, but most of the members
have this diurnally driven convection diminishing after sunset.
A warm front to lift ne over central/se IL overnight as SE winds
shift south to SSW and increase to breezy levels by sunrise Sunday
morning. Milder lows tonight in the mid 50s to around 60F,
mildest from Springfield sw.

Tight pressure gradient over IL in warm sector on Sunday with
south to SW winds having gusts 30-40 mph by late
morning/afternoon. HREF has 30-60% chance of wind gusts over 40
mph from I-55 nw on Sunday afternoon. Warmer highs Sunday in the
upper 70s/lower 80s. After slight chance of convection over
northern/nw CWA overnight into Sunday morning, will see
increasing chances of convection further into central IL during
Sunday afternoon and Sunday night, and into southeast IL
overnight Sunday night. This due to short waves ejecting ne from
Texas into IL along with increasing moisture. SPC keeps risk of
severe storms well west/sw of IL Sunday afternoon and Sunday
night. SPC Day3 outlook has severe risk mainly north and west of
CWA, with marginal risk clipping far northern CWA for late
Monday afternoon/Mon evening, with slight risk further north
over central/southern WI into northern Iowa and southern half of
MN where strong forcing will be. Breezy sw winds continue
Monday with gusts to around 30 mph and warm highs in lower 80s,
with mid 80s from Springfield sw toward MS river valley.

SPC has risk of severe storms over central IL from Paris to
Shelbyville nw on Tue afternoon/Tue night and over much of
central and southern IL on Wed with stronger forcing and
instability around. SW winds gusting 25-35 mph on Tue to bring
warm highs in the mid 80s over the area. Highs in the upper 70s
Wed in central IL and lower 80s in southeast IL. A cold front to
drop into northern IL on Thu and then pushes se through central
IL later Fri night into Sat, likely bringing more showers and
thunderstorms to CWA. Highs in the upper 70s/lower 80s Thu and
lower 80s Friday, cool off next weekend behind a stronger cold
front passing through. WPC has marginal risk of excessive
rainfall over central/nw IL Tue/Tue night and across CWA Wed/Wed
night.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 601 PM CDT Sat Apr 11 2026

Low pressure will move east across the northern Great Plains
into the Upper Midwest tonight and tomorrow. Across central
Illinois, a modest SE breeze currently in place will veer to the
SSW and increase Sunday morning with gusts eventually topping
out in the 25 to 35 kt range Sunday afternoon. Meanwhile, a few
spotty showers are weakening as they approach central Illinois
this evening with PIA having the best chance to see any precip
on station. Otherwise VFR conditions are favored through the
period.

&&

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

&&

$$

KEY MESSAGES...07
DISCUSSION...07
AVIATION...Deubelbeiss