River Forest, Illinois Weather Forecast Discussion

809
FXUS63 KLOT 090518
AFDLOT
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1218 AM CDT Tue Sep 9 2025
.KEY MESSAGES...
- Mostly dry weather expected the remainder of the work week
  with gradually warming temperatures.
&&
.DISCUSSION...
Issued at 208 PM CDT Mon Sep 8 2025
Quiet, pleasant September weather expected through the rest of
the work week, potentially through next weekend, but forecast
uncertainty increases over the weekend.
Rex block over western North America is breaking down and looks
to transition to an Omega block over central portions of the
North America this week. As the Omega block forms, look for
upper ridging to expand eastward into the Mississippi Valley
resulting in warming temperatures and dry conditions. By later
this week, high temperatures should climb well into the 80s, but
with dewpoints expected to remain in the 50s, it shouldn`t be
too uncomfortable.
Shortwave trough is progged to move across the area Tuesday
night into early Wednesday. Low levels are expected to be quite
dry, so expect the radar will light up with virga, but most of
the precip should evaporate before reaching the ground due to
the very dry low levels. Certainly can`t rule out some sprinkles
or even a light shower, but chances for measurable rain look
low.
The 12z operational runs of the GFS and especially the ECMWF
drive a strong cut off upper low from Hudson Bay due south into
the Great Lakes over the weekend into early next week. There
isn`t much support in the ensemble means for these solutions,
owing to quite a bit of spread among ensemble members from both
the EPS and GEFS. If this morning`s operational ECMWF and GFS
runs are onto something, then the weekend could end up cooler
and potentially wetter. Given the wide array of solutions,
confidence is on the lower end of the spectrum and didn`t
deviate from the NBM which is weighted heavily toward last
night`s 00z model runs. Certainly worth keeping an eye on model
trends in coming days.
- Izzi
&&
.AVIATION /06Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 1217 AM CDT Tue Sep 9 2025
Expect VFR conditions through the period with upper-level
cirrus gradually lowering into a mid-level cloud deck. Dry
conditions are also favored, but a slow-moving wave crossing
southern Wisconsin may produce isolated sprinkles or VFR -SHRA
prior to sunrise Wednesday at RFD.
SE winds 5-10 knots early this morning will shift SSW around 10
knots shortly after sunrise. Winds will then settle SSE around
5 knots this evening before veering back SSW/SW late tonight.
Kluber
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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NWS LOT Office Area Forecast Discussion