884
FXUS63 KILX 091746
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1246 PM CDT Wed Jul 9 2025

.KEY MESSAGES...

- There will be daily chances (20-50% coverage) for showers and
  storms over central and southeast Illinois through the
  remainder of the week and into the weekend. Thunderstorms will
  generally be favored during the afternoon and evening hours,
  except for Friday night as a warm front lifts northward across
  the area.

- Seasonable heat and humidity will remain in place the remainder
  of the week into this weekend with afternoon highs generally in
  the mid to upper 80s and dew points in the 70s. Friday will be
  the hottest day this week with highs around 90 and afternoon
  heat indices peaking in the upper 90s to around 100 degrees.

&&

.DISCUSSION...
Issued at 355 AM CDT Wed Jul 9 2025

The predawn surface map shows a frontal boundary draped north of
IL from central lower MI into southeast WI and central Iowa. Radar
mosaic shows scattered showers over eastern parts of Vermilion
and Edgar counties eastward into west central Indiana, with very
isolated light showers in southeast IL. Areas of fog had developed
past few hours over the IL river valley, west of I-55 where low
and mid level clouds had decreased. Though even in the cloudier
areas east of I-55 we are getting some fog with stratus clouds
like at Taylorville with 1/2 mile vsby and 200 foot ceiling. Have
increase coverage of fog over nw half of CWA into early morning
and will see pockets of dense fog too. We will monitor possibility
of dense fog advisory over parts of IL river valley if fog get
more dense and widespread next few hours. Fog should lift by mid
morning while more clouds prevail in east central and southeast IL
today. Isolated to scattered convection to develop this afternoon
with unstable airmass with MLCapes of 1400-1800 J/kg over
southern/eastern CWA but very weak wind shear values around 10
kts. So a few pulsey type storms possible this afternoon with
gusty winds and locally heavy rains. SPC Day1 does not have a
marginal risk over our area today and WPC Day1 ERO has marginal
risk of excessive rainfall over far se IL. Highs today in the mid
to upper 80s with heat indices peaking in the lower 90s this
afternoon.

Isolated convection early this evening otherwise much of tonight
dry. Could see patchy fog develop overnight over ne and eastern
CWA with light winds and moist boundary layer. Lows overnight in
the mid to upper 60s.

Isolated to scattered convection to develop during Thu afternoon
as airmass gets more unstable again especially sw half of CWA as
MLCapes rise back to 1400-1800 J/kg and wind shear values a bit
higher than today at 15-20 kts. SPC Day2 does not have marginal
risk of severe over CWA on Thu afternoon/evening (marginal risk is
over Iowa) but could be a few stronger cells with gusty winds sw
and west central CWA Thu afternoon and early Thu evening. Highs
Thu in the mid to upper 80s and afternoon heat indices in the
lower 90s so similar to todays readings.

A stronger short wave trof moving over the Midwest on Friday to
have higher chances of convection nw of CWA Fri afternoon with our
pops of 30-40% Fri afternoon, and mainly slight chance in
southeast IL. Gets more unstable Fri afternoon with MLCAPES 2-3k
J/kg (highest sw CWA) wind wind shear increasing as well to 25-30
kts by late day. Could be a few stronger storms especially nw CWA
Fri afternoon/evening with low level jet placing a role Friday
night. Warm front lifting northward Fri afternoon and Fri night
to bring hot and humid conditions with highs around 90F and
afternoon heat indices in the upper 90s to around 100 degrees on
Friday. Good chance of convection Friday night and Saturday
especially during the afternoon hours. More unstable airmass is
over southeast IL Sat afternoon with MLCAPes around 2500 j/kg so
could be some strong to severe storms Sat afternoon in southeast
IL.

Models have trended wetter over CWA by Sunday afternoon as a
system approaches from the Central Plains. Heat and more tropical
humidity looks to return early next work week as upper level
ridge builds more into IL as 500 mb heights rise to near or above
591 dm.

07

&&

.AVIATION...  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1239 PM CDT Wed Jul 9 2025

Surface heating getting off to a late start today due to
widespread morning fog and low stratus, cloud bases remain near
the VFR/MVFR threshold of 3kft early this afternoon - most notably
at BMI and CMI where TEMPO groups were included. By 20z, SCT to
BKN clouds should be VFR across the board, with the next
opportunity for MVFR (or lower) conditions arriving around 09z/4am
when once again radiational losses may prove sufficient for patchy
fog; 12z HREF suggests the highest chances (20-40%) for IFR
visibilities will be at BMI and CMI.

Bumgardner

&&

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

$$