065
FXUS63 KLOT 301055
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
555 AM CDT Sat Aug 30 2025

.KEY MESSAGES...

- A pleasant pattern will continue through the holiday weekend.

- An early fall storm system may move through the Great Lakes
  region toward the middle to end of next week accompanied by a
  shot of well below average temperatures.

&&

.DISCUSSION...
Issued at 258 AM CDT Sat Aug 30 2025

A weak mid-level impulse will continue to foster some spotty
light showers across portions of the area through daybreak this
morning. Otherwise, a rather tranquil weather pattern is
expected through the holiday weekend into early next week as
high pressure remains dominant across the Great Lakes region.
Temperatures through the weekend should top out in the low to
mid 70s today under partly to mostly cloudy skies, then warm
into the upper 70s to around 80 for inland areas with more
sunshine for Sunday and Labor Day. Similar weather is slatted
for Tuesday.

The upper-level weather pattern is expected to amplify
significantly across North America next week in response to
anomalously strong mid/upper-level ridging building across
northwestern Canada. The associated buckling of the Polar jet
over this region will act to eject and dig a strong impulse from
the Beaufort Sea south-southeastward right into the Upper
Midwest and Great Lakes region for the later half of next week.
Given the anticipated strength of this system, surface low
pressure development is likely over the Great Lakes region
Wednesday into Thursday of next week in advance of a southward
surging cold front. This thus lends to above average forecast
confidence in our area seeing the next good opportunity (60%+
chance) for rainfall, particularly ahead of the quickly
approaching cold front on Wednesday.

In the wake of the Wednesday cold front passage, robust cold
air advection (especially for early September) on gusty
northwest winds will foster a significant and notable cool down
for Thursday into Friday of next week. In fact, highs may
struggle to climb out of the low to mid 60s both Thursday and
Friday. For climate comparison, the record coldest high
temperature for Thursday the 4th of September is 60 and 61 in
Chicago and Rockford, respectively. Similarly, overnight low
temperatures will be well below average, and may make a run for
the lower 40s (if not colder) outside of Chicago and away from
Lake Michigan. Fortunately, the heart of this unseasonably cold
airmass will shift out of the area in time for the weekend of
the 6th, which will support quickly moderating temperatures back
into the 70s.

KJB

&&

.AVIATION /12Z TAFS THROUGH 18Z SUNDAY/...
Issued at 555 AM CDT Sat Aug 30 2025

There are no significant aviation weather concerns through the
period. However, a deck of low end VFR clouds (4,000-5000 ft
AGL) will persist across the area through much of the day
before scattering out into this evening. Otherwise, with surface
high pressure remaining dominant across the Great Lakes, expect
prevailing light (10 kt or less) easterly winds through the
period.


KJB

&&

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

&&

$$

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