261
FXUS63 KILX 111748
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1248 PM CDT Fri Jul 11 2025

.KEY MESSAGES...

- Slight risk (level 2 of 5) for severe weather this afternoon
  into evening. Damaging winds, hail, a tornado or two, and heavy
  rainfall are forecast. Timing looks to be from 4pm to 12am.

- Daily chances for afternoon/evening thunderstorms will be seen
  through the weekend. SPC has a marginal risk for severe weather
  in place for Saturday and Sunday.

- Hot and humid conditions will be in place through the end of
  this week and again early next week. Temperatures look to trend
  cooler by the end of next week.

&&

.DISCUSSION...
Issued at 320 AM CDT Fri Jul 11 2025

Storms over Iowa are expected to weaken as they get into Illinois
this morning, but some lingering rumbles of thunder and rain are
possible for north central IL early this morning.

Today, the SPC has us in a SLIGHT (level 2 of 5) risk for the areas
north of a Jacksonville to Bloomington line. The marginal risk
(level 1 of 5) expands southward from a Danville to St. Louis line.
A warm front will lift north of the area, bringing more humid air
with it. The suite of CAMs are showing an average of 2000-3000 J/kg
of MLCAPE this afternoon, with the HRRR only showing 1000-2000 J/kg.
Dewpoints will be in the 70s, giving us plenty of moisture,
especially if the corn helps out. Decent 0-1km SRH and bulk shear of
30-40 knots will aid in the severe threat this evening. Timing looks
to be starting around 21z going until about 06z. This is a all
hazards event, with a 5% tornado chance (far northern CWA), 15% (5%)
wind risk north of IL River Valley (north of a Danville to STL
line), and 5% hail risk north of IL River Valley.

A Flood Watch has been issued for Knox, Stark, and Marshall counties
for this evening. These counties saw decent rainfall last night,
making their grounds more susceptible to localized flooding. BUT
these storms will likely have very heavy rain in them, with rain
rates of 1-2 inches per hour. Localized flash flooding is a concern
we have. PWATs of 1.9-2.2 are forecast, which would provide the
atmosphere with enough juice to dump rain on any one location. WPC
has us in a slight risk ERO today north of I-72.

Rain chances continue into Sunday, along with marginal risk of
severe weather from the SPC. Sunday night into Tuesday morning looks
to be dry with ridging taking over. More showers and thunderstorms
return to the forecast Tuesday going into Thursday as another
trough sloshes through.

Today, we will be hot and humid again, with highs in the low 90s and
heat indices of 100-105. A cold front passes over Saturday, dropping
highs into the 80s. By Tuesday, highs will be back into the low 90s.
There is a signal temperatures could cool ever so slightly by late
week.

Copple

&&

.AVIATION...  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1248 PM CDT Fri Jul 11 2025

Primary aviation forecast challenge will be timing the convection
later today. 1730z/1230pm visible satellite imagery shows very
little Cu across central Illinois...suggesting weak subsidence
along/north of an old outflow boundary. As this boundary
dissipates and/or mixes northward, SCT-BKN Cu at 3500-4000ft will
blossom across central Illinois this afternoon. Widely scattered
showers/storms will be possible as well, but areal coverage will
not be great enough to mention in the TAF at this time. Will
monitor radar trends and add thunder if appropriate as the
afternoon progresses. Further west, a line of thunderstorms is
expected to develop along a cold front this afternoon...then push
eastward into central Illinois during the evening. While CAMs
still exhibit some minor timing differences, general consensus
suggests the line will reach KPIA between 01z and 04z...and
further east to the I-55 corridor in a weakening trend between 03z
and 06z. Have included TEMPO groups for thunder at KPIA/KBMI/KSPI
accordingly. Models indicate a further weakening of the convective
line further east, so PROB30s still seem adequate for KDEC/KCMI
overnight. Once the line passes, NAM/HRRR both suggest a period of
MVFR ceilings developing along/west of I-55 by early Saturday
morning.

Barnes

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Flood Watch from 4 PM CDT this afternoon through late tonight
for ILZ027-028-030.

&&

$$