611
FXUS63 KILX 141457
AFDILX

Area Forecast Discussion...Updated
National Weather Service Lincoln IL
957 AM CDT Mon Jul 14 2025

.KEY MESSAGES...

- Areas of dense fog have developed overnight. A Dense Fog
  Advisory is in effect for north of I-70 until 10am.

- Additional chances for strong thunderstorms and flooding return
  by the middle of the week (Wednesday - Thursday) and again by
  next weekend (Saturday).

- Heat indices will get up to 100-105 degrees on Wednesday, before
  a cold front sweeps through Wednesday night.

&&

.UPDATE...
Issued at 955 AM CDT Mon Jul 14 2025

Surface observations and webcams collectively suggest visibilities
have rapidly improved over the past 1-2 hours, so we`ve cancelled
the Dense Fog Advisory. There may still be some localized fog in
low lying areas, but for the most part this has lifted into a low
stratus layer which should gradually thin and lift with surface
heating through lunchtime.

Bumgardner

&&

.DISCUSSION...
Issued at 318 AM CDT Mon Jul 14 2025

Patchy dense fog is hanging around central IL this morning. Some
areas are seeing very limited visibilities. There is a Dense Fog
Advisory out until 15z (10am), but the conditions should start to
improve between 8-10am as the sun erodes the fog layer.

Today will be a dry, but quite typical summer day. Highs today will
being the upper 80s, with lows upper 60s to low 70s. Most of the
area will be dry today. A stationary front is draped across
southeastern Il today. There are some low chance POPs (20% or
less) in our southeast 6 counties this afternoon, but should stay
mostly to our south.

Tomorrow, better shower and storm chances return (30-60%), as the
stationary front starts to shift northward. The storms won`t be
anything organized. They will be of the typical scattered middle
July, popcorn variety. However, any storms that do occur could
produce decent rainfall locally. Forecast soundings show a long,
skinny CAPE profile, slow storm motions (~15-20 knots), and PWATs
around 2-2.3 inches, which would support very heavy rainfall and
localized flooding risk. SBCAPE values are around 2500-3500 J/kg
(depending on the model), with no CIN and low shear. Severe threat
is not expected, but strong wind gusts would be possible within any
stronger downbursts.

Wednesday, there is a marginal risk for severe weather north and
west of the IL River. This will connected to how Tuesday`s storms
evolve on if the risk increases or not. Timing is looking to be an
overnight issue. Currently, the models are showing PWATs around 2
inches, astronomical SBCAPE values (>4000 J/kg), MLCAPE around 2000-
3000 J/kg, and DCAPE around 1000 J/kg. Slow storm motions are shown
on forecast sounds, so another flooding threat? We shall see.

Beyond day 3, periodic chances for showers and thunderstorms exist
into the weekend.

The hottest day of the week looks to be Wednesday with highs around
90s and heat indices 100-105 degrees. Then a cold front will swing
through, dropping daytime temperatures back into the 80s, perhaps
even below normal for mid July.

Copple

&&

.AVIATION...  (For the 12z TAFs through 12z Tuesday Morning)
Issued at 546 AM CDT Mon Jul 14 2025

Dense fog developed overnight, causing very limited visibility and
extremely low ceilings this morning. PIA will be the first to
break free from the fog, becoming VFR by 14z. The other sites
start with VLIFR and LIFR conditions. Then, will see a gradual
improvement as the sun works to erode the fog. All sites should be
VFR for both ceilings and vis by 15z and that is expected to go
through the end of the 12z period.

Copple

&&

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

$$