330
FXUS63 KGRB 261059
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
559 AM CDT Mon Oct 26 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Isolated/scattered light rain/sprinkles overnight into Monday
  morning. Rain chances (30-80%) Monday afternoon into Tuesday,
  highest across central and north-central WI. 50-80% for rain
  Wednesday night, including the potential for a few storms.

- Cooler on Monday with near seasonal temps, then above normal
  temps return Tuesday and continue into next weekend.

- Hazardous conditions begin on Lake Michigan south of Two Rivers
  Monday afternoon then overspread the rest of the nearshore
  waters and possibly the bay of Green Bay Tuesday afternoon into
  Wednesday.

&&

.DISCUSSION...
Issued at 1144 PM CDT Sun Oct 25 2026

Precip and Storm Chances...post frontal shower/sprinkle activity
starting to wane across the area late this evening, but lingering
moisture and weak lift could lead to some additional sprinkles
overnight in Monday morning. Shower activity will then focus
across MN and northwest WI, closer to a low pressure system and
shortwave. However, isentropic lift and a ribbon on moisture will
extend into parts of northeast WI. This will bring rain chances of
30-75% to locations mainly north of Hwy 29 later Monday into
Tuesday morning, highest across north-central WI. The heavier and
most persistent rain will reside over far northwest WI, with
lighter rain expected in our area, with probabilities of over
0.25" of rain through Tuesday night under 35%. Thermal profiles
are showing a below freezing layer between 1000-2000 ft early
Tuesday, which if it materializes, it could be just cold enough
for a little sleet to mix in across far north-central WI. But
think temps will be slow to drop due to the expected cloud cover,
and have opted to stick with just rain. The low-level dry air
feeding into the area on the northeast winds will eat away at the
eastward progression of the shower activity, but some light
showers or sprinkles will spread into parts of eastern WI at
times. Another shortwave and frontal boundary will cross the area
on later Wednesday into early Thursday, bringing a 50-80% chance
for showers. A ribbon of mainly elevated instability will move
into the area late Wednesday (likely after sunset), bringing some
low thunder chances (~20%). Will continue to mention a slight
chance for storms. No severe weather is expected.

Temperatures...northeast/north flow behind the front will usher in
a much cooler day on Monday, with highs ranging from the upper 40s
across north-central WI to the mid 50s in the Fox Valley. The shot
of cooler air will be short-lived, as highs will rebound 5-15
degrees on Tuesday and back into the mid 60s to low 70s on
Wednesday. Above normal temps remain in place Thursday into next
weekend, with highs mainly in upper 50s and 60s, with a 70
possible over the south on Thursday.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 559 AM CDT Mon Oct 26 2026

Early this morning, a cold front is draped from southern Lower
Michigan to central Illinois. North of this boundary, ceilings
generally range from 3.5 to 5 kft across north-central to
northeast WI with scattered light rain showers that is providing
little to no impact to ceilings or visibilities. In fact, ceilings
should hold relatively steady and between 4-7 kft through 00z
Tue. After a lull in the coverage this morning, chances of light
rain showers will increase at AUW and CWA this afternoon and have
added a prob30 to those terminals.

After 00z Tue, the cold front will return north as a warm front
with increasing lift supporting rain chances over much of central
and north-central WI. Went -RA prevailing after 02z at AUW/CWA
and after 04z at RHI. Confidence is for light rain at GRB and
ATW, so a tempo was introduced. With the rain chances, ceilings
will be lowering to MVFR at AUW/CWA/RHI.

A period of northeast winds will impact northeast WI that could
bring gusts 15-20 kts at GRB/MTW after 15z Mon. These gusty winds
should subside after 00z Tue.

&&

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

&&

$$

DISCUSSION.....Bersch
AVIATION.......MPC

NWS GRB Office Area Forecast Discussion