845
FXUS63 KLOT 031938
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
238 PM CDT Sun Aug 3 2025

.KEY MESSAGES...

- Hazy skies and patchy smoke from wildfires lingers today.

- A gradual increase in temperatures and humidity expected
  through the week.

&&

.DISCUSSION...
Issued at 238 PM CDT Sun Aug 3 2025

Through Sunday:

HRRR smoke forecasts for today have largely panned out with the
smoke across the northern half of the local area. Latest HRRR
runs suggest smoke will thin out further on Monday and based on
these forecasts, not planning to have any smoke or haze in the
forecast for Monday.

Some patchy fog will be possible early Monday morning, mainly in
rural locations, but no mention with this forecast.

A very weak mid level trough will pass across the region Monday
through Tuesday as a weak wave lifts north from the southeast
into the southern Great Lakes region. Models are in general
consensus with these trends and show isolated/scattered showers
from Monday afternoon through Tuesday evening, mainly across the
southeast cwa with the best coverage possibly east of the local
area. While there may be some diurnal decrease/increase with the
heating of the day, showers may continue Monday night into early
Tuesday morning. Despite these trends, blended guidance is dry
for all but Tuesday afternoon and made no changes. Instability
looks marginal for thunder, but maintained a chance of thunder
Tuesday afternoon.

The middle to end of the week is looking mainly dry and warmer
as southerly flow brings warmer temperatures back into the area.
High temps by Thursday may be around 90 and then lower 90s
Friday and Saturday. Still some question for how strong the
southerly winds will be and there may be lake breezes each
afternoon, at least along the IL lakeshore.

Models differ quite a bit on the arrival of a cold front later
next weekend or early next week. Too much uncertainty and too
far out to make any changes which have slight chance pops into
the northwest cwa by next Sunday. cms

&&

.AVIATION /18Z TAFS THROUGH 00Z TUESDAY/...
Issued at 1202 PM CDT Sun Aug 3 2025

- Visibility reduction in lingering wildfire smoke and fog patches

High pressure over the southern Great Lakes will begin a slow
retreat eastward into Monday. This will maintain generally
lighter easterly wind (some variation between NE and SE) through
the TAF cycle. Some minor visibility reductions in haze/smoke
(4SM-6SM) will continue through this evening with the light
winds in place. It looks like tomorrow as we get more of a SE
wind that the near surface smoke/haze should ease through the
day. There could also be some patchy fog late tonight.

A slow moving disturbance will spread some higher clouds in from the
south and west later Monday, but any shower activity will
remain well south of the terminals.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Air Quality Alert until midnight CDT tonight for ILZ005-ILZ006-
     ILZ012-ILZ013-ILZ020-ILZ021-ILZ103-ILZ104-ILZ105-ILZ106-
     ILZ107-ILZ108.

IN...Air Quality Alert until midnight CDT tonight for INZ001-INZ002-
     INZ010-INZ011.

LM...None.

&&

$$

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