310
FXUS63 KGRB 270623
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
123 AM CDT Sun Sep 27 2026

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Patchy dense fog is expected over eastern and northeast
  Wisconsin early this morning.

- Light rain showers are possible across central Wisconsin today,
  with better rain chances arriving Tuesday afternoon through
  Wednesday night.

- Trends favor a return to dry weather from Thursday through Saturday
  despite lower forecast predictability.

&&

.DISCUSSION...
Issued at 123 AM CDT Sun Sep 27 2026

High pressure is pumping in a dry airmass across the western Great
Lakes while an approaching low brings mid and high level clouds in
across the region. In areas without so many clouds, some fog is
forming, mainly across northeast Wisconsin and the lakeshore. This
fog should dissipate sometime this morning after sunrise and after
some mechanical mixing. The approaching low will bring a shortwave
some some better moisture in across western Wisconsin during the
day. While most of this precipitation will stay to the west given
the aforementioned feed of dry air from a high over eastern
Canada, some light rain or sprinkles could sneak their way in
across western portions of central and north-central Wisconsin
during the day.

Dry weather and light winds return tonight as the main energy from
the low lifts to the northeast. Models suggest fog will be a bit
more dense and ubiquitous tonight into Monday morning given
abundant low level moisture, clearing skies, and light winds. The
worst of the fog looks like it will be across north-central
Wisconsin, although it could also develop across central Wisconsin
west of Highway 39. Given current trends it would not be entirely
shocking for a Dense Fog Advisory in the future late tonight into
Monday morning, especially for north-central Wisconsin, if trends
continue.

A more widespread period of precipitation is expected from
Tuesday afternoon through Wednesday night. Models have taken a
turn this run, with the chance for half an inch or more of rain
increasing to 40 to 60% and a 20 to 40 percent chance of
receiving one inch or more of rain. This trend is due to the
slower progression of the low through the western Great Lakes,
giving the area more time to reach those rainfall amounts. We are
still only on Sunday, so further adjustments are still possible as
this system gets sampled by the RAOB network.

Dry weather trends favored Thursday through Saturday: Forecast
predictability decreases considerably from Thursday onward due to
a large spread in guidance regarding the evolution of the
southern stream system. Despite this uncertainty, current trends
support a higher potential for dry weather returning to the area
from Thursday through Saturday.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1001 PM CDT Sat Sep 26 2026

VFR conditions are expected throughout most of this TAF period as
high clouds continue to move over the area, with mid-clouds
moving over the central and north-central WI TAF sites after 09z
Sun. Patchy fog will likely develop in far eastern WI early
Sunday morning between 09-14z Sun, causing reduced vsbys to IFR at
GRB/ATW/MTW. However, the prevailing high clouds may limit some
of this development. BKN mid to low-level clouds will continue at
the central and north-central WI TAF sites through Sunday evening
before becoming SCT with the potential for fog development after
06z Mon. Meanwhile, the SCT high clouds will prevail at the east-
central WI TAF sites with some mid clouds arriving Sunday evening.
A few sprinkles or light showers may squeeze out of the BKN mid
to low-level clouds in central and north-central WI, but
confidence remains too low to include in this TAF issuance due to
the isolated nature. Light and variable winds less than 5 kts are
expected throughout the TAF period.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION.....Kurimski
AVIATION.......Kruk

NWS GRB Office Area Forecast Discussion