Oak Lawn, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

683
FXUS63 KLOT 100510
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1210 AM CDT Thu Apr 10 2025

.KEY MESSAGES...

- Lingering showers turning to drizzle tonight into Thursday.

- Temperatures will warm toward the end of the week and into the
  weekend.

&&

.DISCUSSION...
Issued at 305 PM CDT Wed Apr 9 2025

Through Thursday:

A surface low in southeastern Iowa will gradually move eastward
through Central Illinois through the night. It has already
brought light showers across much of the forecast area south of
I-80 this morning, with some small graupel/sleet embedded into
it. Showers will continue tonight over northern Illinois on the
back side of the low as it moves east. There is a chance for
some graupel to remain mixed in but the dominant precip type
through the night should remain rain. Lapse rates remain fairly
steep aloft, but model soundings have more dry air collocated
with the lapse rates keeping the thunder chances fairly low.
Recent hi-res models have also sped up the timing of the of the
rain exiting to the east in the early morning hours on Thursday.
Drier air will slowly sink from the top down, while the lower
parts of the column remain saturated into the morning. It would
not be surprising if shower chances transition over to drizzle
and linger into Thursday morning. Lastly, the southeasterly
winds today will slowly become northeasterly and weaken
overnight. With enough moisture at the low levels, patchy fog
cannot be ruled out, but confidence is low. There should be
enough flow at the surface to prevent widespread fog from
developing.

Another short wave will descend down the parent long wave
trough on Thursday with another weak surface low transversing
south through Iowa. Chances for scattered showers are fairly
limited and most models keep the better chances around or west
of the Fox Valley closer to the low. A thunderstorm cannot be
ruled out, but the instability looks fairly weak and mostly
south and west of the forecast area. Temperatures will warm once
again into the 40s with the potential for some 50s south of
I-80.

DK

Thursday Night through Wednesday:

Upper-level troughing will be slow to clear leading to another
day of near to below average temperatures. Highs should top off
in the low to perhaps mid 50s, except near the lakeshore where
northeasterly winds will hold highs in the 40s. Nearly calm
winds and clear skies will set the stage for chilly temperatures
Friday night, with overnight lows set to fall just below the
freezing mark except within the urban heat island of Chicago.

This weekend, upper-level ridging will develop across the
central US leading to a gradual warming trend. Highs will warm
toward the upper 50s to lower 60s on Saturday (cooler near the
lakeshore), and then the upper 60s to around 70 on Sunday
(areawide, thanks to southwesterly winds).

Ensemble model guidance favors the next upper-level trough and
associated system moving through the region on Monday.
Temperatures will depend on the exact timing of the cold frontal
passage, with an earlier (later) arrival leading to a cooler
(warmer) day. With the GEFS/EPS max temperature interquartile
ranges remaining entirely in the 60s, the NBM-delivered high
temperatures in the low to mid 70s (which are reflected in our
official forecast) currently represent an outlier outcome. The
timing of the front will also be key to precipitation chances,
as an earlier (later) arrival would favor less (more) coverage
of showers and thunderstorms. In all, Monday looks to be a
transition day from warmer to cooler temperatures as the front
slides through the area.

Ensemble model guidance favors another period of near or below
average temperatures during the middle of next week as the low-
level cold pocket associated with the Monday trough meanders
through the region.

Borchardt/DK

&&

.AVIATION /06Z TAFS THROUGH 12Z FRIDAY/...
Issued at 1210 AM CDT Thu Apr 10 2025

A pool of low stratus based between 400 and 500 feet across
southeastern Wisconsin and northeastern Illinois will continue
to slowly ooze southward and stall overnight. With weak
northeasterly winds (generally at or below 6 kt), cigs at
outlying terminals may build downward toward 200 to 300 feet
prior to daybreak. Visibilities should also gradually lower to
the 3 to 4SM range through the overnight hours, and may even
approach 1 mile for a time at RFD. In all, it looks like a
somewhat soupy night.

After sunrise, cigs should ever-so-slowly build upward, with a
trend from LIFR to IFR to eventually MVFR expected from daybreak
to early afternoon. Confidence in cigs from tomorrow afternoon
onward lowers, as northeasterly steering flow ahead of a wave
approaching from the northern Plains may provide a reinforcement
of MVFR stratus. Winds should remain northeasterly through the
TAF, perhaps picking up in magnitude toward 10kt toward the
latter 12 hours of the period.

Borchardt

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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