922
FXUS63 KGRB 011130
AFDGRB

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

Updated aviation portion for 12Z TAF 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 12Z TAF Issuance
Issued at 600 AM CDT Thu Oct 1 2026

Widespread IFR cigs persist this morning, with several sites also
reporting IFR to LIFR vsbys due to patchy ground fog and BR/DZ.
SCT showers/BR have arrived to the east-central Wisconsin
terminals, which should fill in within the next hour or two. Rain
is then progged to continue at times at GRB, ATW, and MTW through
this afternoon. Less confident in steady rain making it to AUW
and CWA as they skirt the northern periphery of the rain shield,
though have included PROB30 mention of SHRA in the TAF.

As rain comes to an end this afternoon, cigs should gradually
lift to VFR from northwest to southeast as cooler and drier air
filters in behind a cold front. Have all sites returning to VFR
flying conditions by around 21Z.

Winds continue to shift to the northwest through this afternoon.
Gusts between 15 and 20 knots will be possible at AUW, CWA, and
RHI during this time.

&&

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

&&

$$

DISCUSSION.....Goodin
AVIATION.......Goodin

NWS GRB Office Area Forecast Discussion