940
FXUS63 KGRB 291132
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
632 AM CDT Fri Aug 29 2025

.KEY MESSAGES...

- Other than some showers across central Wisconsin today,
  generally dry weather is expected through the weekend with
  temperatures rebounding into early next week near to above
  average.

- Areas of fog may develop tonight (40-80% chance), highest
  chances across north-central Wisconsin. Fog may be locally
  dense in spots.

- Next chance for rain centered mid-next week (40-60% chance)
  with much cooler air likely for late in the week.

&&

.DISCUSSION...
Issued at 224 AM CDT Fri Aug 29 2025

Today-Monday:

Surface high pressure was centered across Lake Superior early this
morning. The 00Z sounding at GRB showed a dry airmass in place
(precipitable water around 0.5 inches) with the Canadian high.
Through the weekend, the surface high will slowly migrate eastward
as northern stream mid-level ridging works eastward across the
region. Thermal profiles will gradually moderate through the weekend
with the ridging building in, resulting in temps rising back near to
above average through the holiday weekend. A plume of
seasonably moist air will generally extend northward into the
northern plains this weekend where weak mid-level southern
stream troughing will be found. Thus, the higher shower chances
will generally be focused west of the area into early next week.
However, showers may brush parts of central Wisconsin this
afternoon/evening as a weak embedded shortwave trough swings
through with some mid-level warm advection/frontogenesis.

A deeper layer of light winds overnight tonight under high
pressure should support some fog development during the predawn
hours on Saturday. The HREF shows medium to high probabilities
(40-80%) for fog development across northern Wisconsin early
Saturday, possibly dense in spots.

Tuesday-Thursday:

A pattern shift is expected by mid next week with a transition to
western US ridging and Great Lakes/eastern US troughing.
Although there are still some differences in amplitude/evolution
of the trough, rain chances look to be maximized around
Wednesday (40-60% chance) as the front moves through followed by
much cooler late week temps. There are high probabilities
(>70%) for below average temps late in the week - highs may
struggle to top 60 degrees later in the week. The pattern would
favor breezy winds and perhaps some showers within the cyclonic
flow aloft lingering into the late week period. It looks to be
another early taste of fall weather. However, ahead of this
system, ensemble guidance shows small overall temperature
spread through through Tuesday with temps likely in the 70s to
low 80s.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 609 AM CDT Fri Aug 29 2025

Patchy IFR fog/stratus early this morning will give way to
mainly VFR conditions and light winds through the remainder of
the day. Although a shower could not be completely ruled out at
KAUW/KCWA this afternoon, the higher chances remain to the south
and west.

Overnight tonight, a relatively deep layer of light boundary
layer flow will support areas of fog development, with the HREF
showing the highest probabilities (40-80%) across northern
Wisconsin, and potential for LIFR visibilities. Have trended
the TAFs towards this scenario, especially across central into
northern sites.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
WI...Frost Advisory until 8 AM CDT this morning for WIZ005-010>012.
MARINE...None.

&&

$$

DISCUSSION...JM
AVIATION...JM
MARINE...