Normal, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

519
FXUS63 KILX 041754
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1254 PM CDT Mon May 4 2026

.KEY MESSAGES...

- There is a 50-80% chance southwest winds gust over 35 mph
  today near and east of the I-55 corridor, promoting patchy
  blowing dust especially in areas that have recently missed the
  rains. This can result in localized, sharply reduced
  visibilities for motorists.

- Isolated to scattered showers and thunderstorms are forecast
  through the afternoon, and become more widespread tonight.
  There is slight to marginal risk for large hail and damaging
  wind gusts, mainly during the 7 pm to 1 am timeframe. The
  higher risk of severe storms this evening (slight risk with
  level 2 of 5) is from Shelbyville to Danville north, and
  south of Knox, Stark and Marshall counties.

&&

.UPDATE...
Issued at 1045 AM CDT Mon May 4 2026

Updated the forecast to adjust chances of showers and
thunderstorms the rest of today. Continued Blowing Dust Advisory
from 11 am to 6 pm southeast of the IL river and north of
Effingham, Cumberland and Clark counties. SW winds 10-20 mph
and gusts of 20-30 mph to increase this afternoon with gusts
30-40 mph possible especially over east central IL per latest
HRRR 10M wind gust forecast. This could lead to blowing dust in
recently tilled fields between the IL river and I-70, especially
in areas that stayed dry so far since last night.

Radar mosaic shows a band of showers and thunderstorms from
Springfield to Decatur to Paris south to near I-70 and tracking
eastward quickly at 50 mph. There is a subtle short wave
tracking quickly eastward with this convection along with 30-40
kt sw low level jet into central IL. This convection should
weaken next few hours as LLJ weakens and short wave moves into
Indiana. However more convection expected to develop late this
afternoon and early evening mainly se of I-55, and also during
this evening over nw CWA as cold front moves into nw IL during
this evening. SPC Day1 outlook continues marginal risk of severe
storms for large hail and damaging winds over much of IL for
mainly late afternoon and evening hours, with areas from Canton
to Decatur to Taylorville sw upgraded to a slight risk of severe
storms. Breezy sw winds and some sunshine to warm temperatures
to 75-80F degrees.

&&

.DISCUSSION...
Issued at 246 AM CDT Mon May 4 2026

***** BREEZY AND WARM WITH PATCHY BLOWING DUST TODAY *****

At 230am, scattered thunderstorms were ongoing across areas near and
south of a roughly Jacksonville to Paris line where 30-40 kt
effective bulk shear and 250-500 J/kg MUCAPE rooted around 850mb
were apparent on SPC`s mesoanalysis page. Radar presentation would
suggest the cores of the strongest storms are producing small hail,
though the general trend is toward weakening storms as instability
continues to wane. CAMs suggest this activity will wane through
daybreak, though the leftover outflow boundary may serve as a focus
for a few lingering showers through afternoon by which time surface
heating will bring a resurgence of instability. The High Resolution
Ensemble Forecast (HREF) and Rapid Ensemble Forecast System (REFS)
mean SBCAPE climb to 1000-1500 J/kg by late afternoon, though
forecast soundings also advertise a capping inversion which should
inhibit realization of that instability until LLJ ramps up during
the evening.

With enough sunshine, deep mixing will promote temperatures warming
into the upper 70s to low 80s by mid afternoon. It will also result
in gusty southwest winds, with Bufkit soundings showing winds
approaching 40 kt (46 mph) at the top of the mixed layer - a
reasonable estimate for peak gusts - in east central Illinois. Given
we had blowing dust yesterday afternoon with similar wind speeds, we
elected to issue a Blowing Dust Advisory for areas north of I-70 and
east of the Illinois River, where the risk appears greatest due to
soil type and expected winds. (While several of the counties in this
Advisory received rain from storms early this morning, the spotty
nature of that rainfall and tendency for the near surface topsoil to
quickly dry out made us think the potential is still significant
enough, particulary along highways, to issue.)

***** STRONG STORMS TONIGHT, RAINY AND COOL TUESDAY *****

As a 40-50 kt LLJ ramps up ahead of a cold front this evening,
scattered storms are forecast to develop, posing primarily a risk
for locally damaging winds and large hail given steep mid level
lapse rates and dry air in both the mid levels and below cloud bases
(around 850mb). Given high LCLs, the tornado risk appears low (less
than 2%), but SPC maintains a level 1 of 5 (marginal) risk for wind
and hail. After midnight, coverage of storms is slated to
increase while instability gradually wanes, lowering the risk
for severe weather but bringing more widespread rain, which will
continue in waves into tomorrow night. While this rainfall will
be spread out over 24+ hours, we can`t fully rule out
hydrological issues south of I-72/Danville where some spots
received up to 5 inches last week and where NBM gives a 5-15%
chance for more than 2 inches; WPC has a level 1 of 4 (marginal)
risk for excessive rainfall near and east of a roughly
Shelbyville to Danville line. Behind the cold front tomorrow
into Wednesday, it`ll be quite chilly with afternoon highs in
the mid to upper 50s.

***** STAYING COOL WITH LOW PRECIP CHANCES LATE WEEK *****

The parent upper level trough will linger over Ontario late week,
with shortwaves orbiting it and offering the local area with
periodic, low (15-30%) shower chances and shots of chilly Canadian
air through the early part of the weekend. While global models and
their respective ensembles differ in how long it will take for this
upper level trough to retreat to the northeast, NBM`s
probabilistic distribution for daily high temperatures shifts
up each day Thursday through Saturday. For example, the 25th
percentile (75% chance of warmer temperatures) in Lincoln
increases from 57 Thursday to 65 Friday to 70 Saturday.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1255 PM CDT Mon May 4 2026

A band of showers and isolated thunderstorms was se of BMI and
went to Champaign and Danville areas and to affect CMI airport
next hour or so with possible brief MVFR vsbys. Isolated
convection to develop late this afternoon and early evening and
become more scattered later this evening into overnight as
ceilings lower to MVFR from I-55 se. Showers to diminish from
the west and nw during mid to late Tue morning from I-55 nw and
likely continue at CMI and DEC into Tue afternoon. Breezy SW
winds 15-22 kts with gusts 25-32 kts this afternoon could cause
blowing dust at CMI and BMI but recent rainfall at CMI may limit
that. SSW winds to diminish to around 10 kts during this evening
and switch north to NNE between 06Z-10Z overnight as cold front
moves se through central IL, starting at PIA and last at DEC
and CMI, and continue into Tue.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Blowing Dust Advisory until 6 PM CDT this evening for ILZ031-
037-038-041>048-050>057-061.

&&

$$

KEY MESSAGES...Bumgardner
UPDATE...07
DISCUSSION...Bumgardner
AVIATION...07