Northerly Island Park, Illinois Weather Forecast Discussion

000
FXUS63 KLOT 160805
AFDLOT
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
305 AM CDT Tue Sep 16 2025
.KEY MESSAGES...
- Warm and dry conditions persist through the work week.
- Periodic shower and thunderstorm chances return this weekend
  into early next week (20-40%).
&&
.DISCUSSION...
Issued at 305 AM CDT Tue Sep 16 2025
Expansive surface high pressure across the broader Great Lakes
region early this morning has led to continued mostly clear
skies and light and variable to calm winds. Radiational cooling
across interior northern Illinois may lead to patchy shallow fog
development through daybreak but coverage should remain much
lower than seen over the weekend given overall drier low-levels.
A blocky upper-level flow pattern across the eastern CONUS will
continue to support quiet weather conditions across our area
through the work week. Mostly clear skies each day will foster
unseasonably warm temperatures, with inland highs in the 80s to
near 90 (warmest toward western and central Illinois) through
the remainder of the work week. Closer to the lake, relatively
weak surface flow will allow lake breezes to push inland each
afternoon. This will thus result in cooler temperatures (mainly
in the 70s) near the Lake Michigan lakeshore.
While quiet and dry weather will persist in this blocked
pattern through the rest of the work week, the upper level ridge
begins to break down heading into the weekend as a western
trough (and/or potential cut-off low) begins to slide eastward
towards the Great Lakes. This will lead to increasing chances
for periodic showers and thunderstorms over the weekend into
early next week.
Petr/KJB
&&
.AVIATION /06Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 1231 AM CDT Tue Sep 16 2025
No major forecast concerns are expected through the TAF period
as high pressure remains overhead. Therefore, expect light and
variable winds tonight to become east-northeast Tuesday morning
with speeds in the 5-7 kt range. Skies will remain mostly clear
through the period though some occasional passing cirrus is
possible especially at RFD.
Finally, there is some shallow fog developing in far northeast
IL and southern WI. Given the large temperature-dew point
depressions (around 5-6 degrees) suspect fog will struggle to
develop at the terminals and thus have forgone a formal mention.
That said, did add a TEMPO at GYY for some 5SM BR given the low
temp-dew point depression here and some fog being noted in Lake
County, IN. Fog will erode after daybreak Tuesday morning.
Yack
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
Visit us at weather.gov/chicago

NWS LOT Office Area Forecast Discussion