850
FXUS63 KLOT 231114
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
614 AM CDT Sat Aug 23 2025

.KEY MESSAGES...

- Slight chance (20%) for a few thunderstorms this afternoon.

- Fall-like temperatures early/mid next week.

&&

.DISCUSSION...
Issued at 212 AM CDT Sat Aug 23 2025

Primary forecast concern is a chance of thunderstorms this
afternoon. A few showers are ongoing across east central IA
early this morning and isolated showers will be possible across
northern IL this morning, possibly developing over the area
around daybreak. These are expected to dissipate through late
morning with a brief lull for precip chances midday. Then as the
main cold front pushes across the area this afternoon, there
will be a low chance (20%) for a few thunderstorms, roughly
along and east of I-55 and then ending by 00z. While its
possible that most of the area may remain dry, given the shear
aloft, if any storm can form, it may have the potential to
produce locally gusty winds.

Northwest winds will gust into the mid 20 mph range behind the
cold front this afternoon and then diminish with sunset over
land but continue to be gusty over southern Lake Michigan. These
northwest winds will remain gusty at times over the lake through
Monday night, which will allow for high waves and likely
dangerous swimming conditions for beaches at least along the
Porter County Lake Michigan shore and we`ll need to monitor for
a possible beach hazard statement.

Lake effect rain showers will be possible Sunday night and again
Monday night for mainly Porter County in northwest IN, though
overall confidence is fairly low and will be dependent on the
wind directions. There is also the potential for a few
waterspouts during this time period though the better conditions
may remain to the north and northeast of our marine area and not
planning any mention for now.

Temperatures will trend cooler behind this cold front with highs
generally in the 70s Sunday through Thursday with Monday looking
to be the coolest day with some areas possibly struggling to
reach 70 for high temps. Outside the Chicago urban area, low
temps in the 40s look likely Monday, Tuesday and Wednesday
mornings. cms

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/... Issued at 600 AM CDT
Sat Aug 23 2025

- Brief period of VFR SHRA near MDW/GYY in the afternoon,
  isolated TS southeast of the terminals.

- Breezy WNW winds with gusts 20-25 kt this afternoon.

A leading band of isolated showers will slide through the
terminals at the start of the TAF period while more scattered
showers pass to the southwest of the Chicago area. Lower VFR
conditions will accompany these showers.

After a period of clearing this morning, a cold front will
shift through late morning into the afternoon. Instability will
rebuild ahead of the front, with the frontal speed pivotal to
determine whether a brief period of showers will occur near the
Chicago terminals. Current guidance suggests most of the
Chicago TAFs remain dry given that the moisture layer will be
somewhat shallow before the front clears. MDW, and more so GYY
would be briefly favored in the 19z-21z window. A few
thunderstorms may also develop downstream along the ORD
southeast arrival track (SE of KGYY) mid to late afternoon.

Winds will shift to northwest and increase in late morning into
the afternoon, with gusts in the lower to mid 20s. Expect a mix
of clear skies or scattered lower VFR clouds tonight into
Sunday and somewhat lighter NW winds,

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...Beach Hazards Statement from this evening through Sunday
     morning for INZ002.

LM...None.

&&

$$

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