664
FXUS63 KGRB 051652
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1152 AM CDT Mon Oct 5 2026

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Light rain showers will move across northern Wisconsin late
  tonight into early Tuesday morning.

- Breezy southwest winds gusting 25 to 35 mph are expected to create
  hazardous marine conditions Tuesday morning through early
  Wednesday morning. Marine headlines have been issued.

- Patchy frost will be possible over far northern Wisconsin Thursday
  and Friday nights with low temperatures in the mid 30s.

&&

.DISCUSSION...
Issued at 1151 AM CDT Mon Oct 5 2026

The current surface analysis displays high pressure positioned
over the western Great Lakes, delivering clear skies and pleasant
fall conditions across northern Wisconsin. On the western flank of
the ridge, warm advection is increasing across the Northern
Plains ahead of a shortwave trough advancing through central
Canada. Zonal upper-level flow will prevail through the week,
keeping the storm track generally north of Wisconsin with
temperature swings and limited moisture return.

Light Rain Showers Northern Wisconsin Tonight: As the surface
high slides east tonight, low-level moisture transport will
increase across the Upper Mississippi Valley. Moisture convergence
on the nose of a 30-knot low-level jet will support scattered
light rain showers moving into north- central Wisconsin late this
evening and clearing by Tuesday sunrise. NBM guidance indicates a
40 to 60 percent probability of 12-hour precipitation exceeding
0.01 inches at Rhinelander and Land O Lakes, but only a 25 to 35
percent chance of reaching 0.10 inches. High-based cloud ceilings
between 5,000 and 7,000 feet will prevent significant visibility
reductions as showers shift eastward into Michigan.

Breezy Tuesday Winds: A tightening surface pressure gradient
ahead of the approaching cold front will drive strong south to
southwest winds on Tuesday, with inland daytime highs reaching the
lower to mid-70s. Deep boundary layer mixing will support gusty
winds of 30 to 35 mph across central and eastern Wisconsin during
Tuesday afternoon.

Late Week High Pressure Patchy Frost: Canadian surface high
pressure building across the Great Lakes Thursday and Friday will
reinforce a cool, dry airmass and maintain dry conditions. Strong
radiational cooling beneath clear skies and light winds Thursday
night and Friday night will drop overnight minimum temperatures
into the mid to upper 30s across north-central Wisconsin. NBM
probabilistic guidance shows a 30 to 50 percent probability of
temperatures falling to 36 degrees or colder in low-lying spots
near Eagle River, Rhinelander, and Crandon each night.
Temperatures will rebound into the upper 60s and lower 70s over
the weekend as southerly return flow re-establishes, with low-end
rain chances of 15 to 25 percent returning late Sunday.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1151 AM CDT Mon Oct 5 2026

Good flying weather will continue this afternoon thanks to surface
high pressure. As this surface high slides east, a band of light
showers are expected to develop over Minnesota and track east
across northern Wisconsin tonight. These showers will likely fall
out of a 5-7 kft cloud deck. Confidence is highest at KRHI for a
few hours of light rain and a tempo group has been added. prob30
groups have been added to rest of the TAF sites (KAUW, KCWA, KGRB,
KATW, KMTW). Flight conditions will likely remain VFR in the
showers due to their high based nature.

After the rain ends by 9-11Z, wind shear to 35 kts are expected to
move into central and north-central WI on Tuesday morning. These
winds will start to mix down to the surface by mid to late morning
and create gusts from 20-30 kts from the south or southwest
through Tuesday afternoon.

&&

.MARINE...
Issued at 1151 AM CDT Mon Oct 5 2026

Southerly winds of 15 to 25 knots with gusts to 30 knots will
build waves to 5 feet on Green Bay and 6 to 10 feet on Lake
Michigan on Tuesday and Tuesday night. Winds look to remain below
Gale Warning criteria. Consequently, the Gale Watch will be
converted to a Small Craft Advisory for the nearshore zones. High
confidence exists in these hazardous marine conditions.

&&

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

&&

$$

DISCUSSION.....MPC
AVIATION.......MPC
MARINE.........MPC

NWS GRB Office Area Forecast Discussion