393
FXUS63 KGRB 010630
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
130 AM CDT Thu Oct 1 2026

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Periods of light to moderate rain are forecast to continue over
  central and east-central Wisconsin into this afternoon.
  Additional rainfall amounts up to around 0.5" are expected.

- Patchy frost will be possible at times across northern Wisconsin
  into the weekend. Greatest chance for a widespread frost/freeze
  event will be Sunday night into Monday morning.

&&

.DISCUSSION...
Issued at 100 AM CDT Thu Oct 1 2026

Rain chances today... Radar currently shows a broad area of
stratiform rain spreading across southern Wisconsin early this
morning where decent moisture convergence and weak FGEN reside.
This rain should make it up into portions of central and east-
central Wisconsin over the next several hours as moist conveyor
belt lifts north and interacts with cold frontal passage and weak
coupled shortwave. Axis of heaviest rain should remain off to our
south, with probabilistic guidance only showing a 40 to 70% chance
for receiving 0.5" of QPF over east-central Wisconsin. Areas
north of Hwy 29 have a good chance of missing out on the rain
entirely. Rain eventually comes to an end from northwest to
southeast this afternoon as cooler and more stable air filters in
behind the front.

Patchy ground fog, locally dense, will be possible through this
morning due to saturated boundary layer. Will be tough to pull
the trigger on an advisory due to low stratus regime and generally
moist airmass, though will continue to keep an eye on obs.

Extended... After showers wrap up later today, pattern through
the middle of next week will be characterized by mostly dry
weather and near to slightly below normal temperatures as upper
flow flattens out and high pressure builds. Only exception will be
30 to 50% chance of light rain north of Hwy 29 Saturday evening as
transient shortwave and weak cold front move through the upper
Midwest. Otherwise, frost/freeze setup remains on track for Friday
night into Saturday morning, and again Sunday night into Monday
morning as surface high sits overhead and 850 mb temperatures fall
to near, or even slightly below, 0C. As it stands now, better
setup for a widespread frost/freeze event looks to be early Monday
morning. With mostly clear skies providing effective radiational
cooling, some of the cold spots across the north may even dip
below freezing during this time. Will continue to monitor for
headline potential.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 952 PM CDT Wed Sep 30 2026

A cold front over northwest Wisconsin will gradually drop
southeast as a low pressure system tracks from the Central Plains
tonight across northern Illinois on Thursday morning.

As the low tracks closer, light rain chances will increase in the
08-18Z Thu period, mainly over east-central WI. KATW and KMTW
have the greatest potential to be impacted from the showers. KGRB,
KAUW, and KCWA will be on the northern periphery, but confidence
of shower activity is increasing in the 11-16Z timeframe.
Regardless, lowering ceilings should result in widespread LIFR/IFR
conditions along with IFR/MVFR visibilities.

As rain potential ends after 16-18Z Thu, winds will shift to the
northwest and finally usher in drier low level air. Will therefore
see ceilings increase with a return to VFR conditions possible at
all terminals by 21-22Z Thu.

&&

.MARINE...
Issued at 100 AM CDT Thu Oct 1 2026

Southerly winds continue to decrease overnight, though waves
remain elevated along the Lake Michigan nearshore waters. Waves
should come down within the next couple of hours, after which
marine and beach hazards will come to an end.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Beach Hazards Statement until 4 AM CDT early this morning for
WIZ022-040-050.
&&

$$

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