775
FXUS63 KGRB 200517
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1217 AM CDT Tue Oct 20 2026

Updated aviation portion for 06Z TAF issuance

.KEY MESSAGES...

- Dry this week. Next chances for rain (25% or less) this
  weekend.

- Late night, early morning fog expected this week, starting
  tonight into Tuesday morning. Patchy dense fog is possible.

- Temperatures remain above normal through the weekend. Highs may
  reach or exceed 70 degrees (probability of 30-50%) in portions
  of central and far northeast WI, Wednesday through Sunday.

&&

.DISCUSSION...
Issued at 1146 PM CDT Mon Oct 19 2026

Mostly Dry This Week...The region will be under the influence of a
ridge of high pressure through at least Friday, keeping conditions
dry under mostly sunny skies. Guidance indicates the next chance for
rain sometime this weekend as a mid-level trough and surface low
eject northeast from the Middle Rockies. Any precip will be
associated with the surface low`s cold front as it sweeps across the
Upper Mississippi Valley, with the earliest guidance starting late
Saturday night and with the latest guidance exiting on Monday.
However, forcing and moisture is rather lacking due the cold front
becoming too far removed from the surface low. This leaves the
forecast area with low chances for measurable precip (0.01") of less
than 25%.

Fog Potential...The prevailing high pressure combined with nighttime
cooling and light winds will result in the potential for at least
patchy ground fog each night/morning from tonight through Thursday
night. Patchy dense fog may occur during these times.

Temperatures...This weather pattern will keep above normal
temperatures in the forecast through the weekend with highs mainly
in the 60s each day. A few spots in central and far northeast WI may
reach into the low 70s a couple of the days, from Wednesday through
Sunday, as NBM probs for 70 degrees or warmer sit around 30-50%
each day. After tonight`s low temps in the low 30s to low 40s,
overnight lows will be rise above normal through the weekend, with
values mainly in the 40s.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1217 AM CDT Tue Oct 20 2026

Primary aviation concern through the TAF period will be possible
fog development early this morning. Guidance is most aggressive with
fog across east-central into far north-east WI, so have included
TEMPO grounds with IFR vsbys at ATW, GRB, and MTW. Not as confident
in fog impacting AUW and CWA, but do have TEMPO groups with MVFR
vsbys. Where fog does develop it may linger through mid-morning as
the late sunrise and light surface winds will slow mixing. Otherwise
VFR conditions are expected through the day Tuesday.

Winds will be light and variable overnight, turning S/SE Tuesday
afternoon and remaining less than 10 kts.

&&

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

&&

$$

DISCUSSION.....Kruk
AVIATION.......GK

NWS GRB Office Area Forecast Discussion