667
FXUS63 KILX 311101
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
601 AM CDT Fri Jul 31 2026

.KEY MESSAGES...

- There is a Marginal Risk to the IL/IN border and a Slight Risk
  in place for areas southwest of a Macomb-Havana- Taylorville
  line. The primary threat today is damaging wind gusts of 60
  mph. Timing mid afternoon into evening.

- Periods of heavy rain will spread across the area between
  Friday and Saturday. Slow-moving thunderstorms Friday night
  into Saturday morning will increase the risk for localized
  flash flooding over saturated ground. Total rainfall will
  average 1 to 2 inches across central Illinois, though
  localized spots could see 3 to 4+ inches where heavy rain
  bands repeat.

- Outside of thunderstorms Saturday, winds will be quite gusty.
  The HREF shows a 70-100% chance of wind gusts greater than 35
  mph west of I-55 during the afternoon and evening hours.

&&

.DISCUSSION...
Issued at 200 AM CDT Fri Jul 31 2026

An active weather pattern returns today as a low pressure system
moves through the central part of the United States today and
tomorrow. Showers and thunderstorms will be pushing through central
and southeastern IL the next few days in multiple waves. The next
few days won`t be a complete washout as there will be breaks in the
rainfall. There will be a dry slot that will push into the area
overnight tonight into tomorrow morning, before additional storms
develop tomorrow morning. Outside of any storms, skies will be
cloudy.

Our main concern with this system is the heavy rain potential. The
first wave will enter western IL by 12-13z this morning. Between 12z
this morning and 12z Sunday, we are forecasting 1-2.5 inches of
rainfall. The greatest probabilities of rainfall amounts exceeding 2
inches is north of I-72. The greatest rainfall amounts won`t be
widespread and fairly localized. Some localized areas could see 4-7
inches of rain based off the 00z HREF LPMM accumulated
precipitation. WPC has us in a slight risk ERO for today and a
marginal risk for tomorrow. Flash flooding could occur where grounds
are already saturated or after multiple rounds of heavy rain over
the same locations.

The SPC just expanded the severe threat for today to encompass our
entire forecast area with Marginal Risk to the IL/IN border and a
Slight Risk in place for areas southwest of a Macomb-Havana-
Taylorville line. The primary threat today is damaging wind gusts of
60 mph. MUCAPE will be highest in the slight risk area with values
of 1000-2000 J/kg mid to late afternoon today. The shear values are
around 30-40 knots.

The severe threat goes down overnight into Saturday, but MUCAPE
value will remain ~1000 J/kg into Saturday. SPC does not have us
outlooked at this time for Saturday. Although, a 2% tornado threat
could be introduced potentially. The low pressure center will move
directly overhead on Saturday, increasing the non-supercell tornado
parameter. Even if the low tornado chance doesn`t pan out, someone
may see a funnel cloud(s) across central IL. Outside of
thunderstorms, winds will be quite gusty. The HREF shows a 70-100%
chance of wind gusts greater than 35 mph west of I-55 during the
afternoon and evening hours.

Temperatures will cool off today into Sunday with highs in the mid
70s to low 80s. Temperatures gradually increase solidly back into
the 80s, nearing 90 degrees by Friday next week. Lows will be in the
60s for the next week before warming to around 70 degrees by
Thursday night.

Weather will dry out for Monday, but additional rain chances muddle
the new week starting Tuesday. There are low (~20%) chance for rain
off and on throughout next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 601 AM CDT Fri Jul 31 2026

Deteriorating conditions are expected as a low pressure system
brings waves of showers and storms beginning 15z-18z. MVFR
cigs/vsbys are anticipated by 15z-18z from SPI-BMI and
northwestward, perhaps eventually reaching IFR especially near
PIA. At DEC-CMI, primarily VFR cigs with periods of MVFR vsby
are expected. IFR cigs are likely to spread across the entire
area after 09Z Saturday. Winds increasing to SSE 12-15 kts with
gusts 20-25 kts by 16z.

&&

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

&&

$$

KEY MESSAGES...Copple
DISCUSSION...Copple
AVIATION...Copple