122
FXUS63 KGRB 061756
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1256 PM CDT Mon Oct 6 2025

Updated aviation portion for 18Z TAF issuance

.KEY MESSAGES...

- Conditions hazardous to small craft continue on Lake Michigan
  through 7 AM this morning.

- Rain chances continue through tonight. Total rainfall will
  generally be held down to 0.25" or less, though there is a 40 to
  60% chance of seeing 0.5 to 1" of rain in parts of central
  Wisconsin.

- Turning much cooler early this week, with a frost or freeze
  likely for portions of central, north-central, and far northeast
  Wisconsin Tuesday night. Patchy frost could occur in the Fox
  Valley.

&&

.DISCUSSION...
Issued at 218 AM CDT Mon Oct 6 2025

Short Term...Today...Tonight...and Tuesday

Rain/storms... Latest obs and radar show that the cold front has
moved into the central part of the state early this morning, with
a broken line of showers ongoing. East-central Wisconsin remains
dry as of this forecast issuance. The front will continue to trek
southeast throughout the day, bringing with it periods of off and
on rain to eastern Wisconsin. Suspect that thunder chances would
be rather limited given meager instability, though a rumble or two
would not be out of the question. CAMs are starting to pick up on
a signal, albeit weak, for isolated pockets of heavier rain
within a narrow corridor of deeper moisture behind the front,
which comes much needed given the prolonged stretch of dry
weather. Probabilistic guidance currently shows around a 40 to 60%
chance of receiving 0.5 - 1" of rain over central Wisconsin,
which is where showers are expected to reside the longest. Rain
chances then come to an end area-wide by early Tuesday morning,
giving way to high pressure and a building ridge.

Winds/marine... Winds subside and veer to northwesterly behind the
front this afternoon as the pressure gradient loosens up, though
latest obs still show gusts to 15 to 20 mph early this morning. As
such, waves on Lake Michigan stay up between 3 and 6 ft through
around 12Z, when the current Small Craft Advisory is set to
expire. No additional headlines or extensions are anticipated.

Long Term...Tuesday Night Through Sunday

Primary themes in the long term are minimal chances for precipitation
through next weekend, along with the potential for widespread frost
early this week. Warmer weather not done though, as temperatures
rebound into the 70s next weekend.

Precipitation...
A weak front could bring showers over the western Great Lakes
Thursday night into Friday. Otherwise, next chance for more
widespread showers will not occur until next Sunday night or
Monday as the warm front shifts east from the plains. Significant
precipitation totals are not expected from either system.

Temperatures/Frost Potential/Fire Weather...
In wake of the cold front moving through, much cooler temperatures
expected through early Thursday. Coldest night across the entire
area, by far, will be Tuesday night. High pressure overhead with
clear skies, light winds and PWATS less than 25th percent of
normal result in conditions that will be ideal for widespread
frost, with many locations over northern WI seeing a freeze. This
will not be just a marginal event that only impacts typical cold
spots. It is looking likely that all locations north of a line
from Stevens Point and Wisconsin Rapids to Oconto will see temps
around or below freezing. Temps as low as the mid 30s with patchy
frost may occur in the Fox Valley. Thought about issuing Freeze
Watch on this shift, but will let dayshift take another look. Will
start to message it stronger though. Wednesday night will see more
frost (northern WI to far northeast WI), but with less areal coverage
as temperatures begin slowly moderating.

Temps begin to rise again mid to late week. Highs back into the
upper 60s Friday, with a few 70s showing up on Saturday as the
high shifts to the east and warm front develops over the plains.
Probabilities of seeing highs over 70 increase on Sunday, as does
the pressure gradient and SE winds. NBM probabilities showing
chances are 60-80% that wind gusts could exceed 25 mph next
Sunday, but only 20-30% chances of seeing gusts over 35 mph.
The relatively extended period of dry weather, drying and curing
fuels certainly aided by freeze in some areas Tuesday night, could
lead to return of fire weather concerns next weekend, especially
if it turns breezy.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1256 PM CDT Mon Oct 6 2025

Scattered showers will continue to move across the region today,
impacting mainly ATW, GRB, and MTW in eastern Wisconsin. A second
surge of moisture could still bring some showers to central
Wisconsin in the afternoon however, so added a PROB30 group to AUW
and CWA to account for any showers that may get further
northwards. Ceilings under the showers are largely MVFR, but
improvement to VFR is expected over the course of the evening as
drier air moves in.

Winds today and tonight will remain fairly light, but a few gusts
up to 15 knots will be possible tomorrow afternoon.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Freeze Watch from Tuesday evening through Wednesday morning for
WIZ005-010>013-018>021-073-074.
&&

$$

DISCUSSION.....Goodin/JLA
AVIATION.......Uhlmann