249
FXUS63 KGRB 070351
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1051 PM CDT Sun Jul 6 2025

Updated aviation portion for 06Z TAF issuance

.KEY MESSAGES...

- Areas of fog possible in the Wisconsin River Valley late
  tonight.

- Seasonal summer weather is expected over the next week. Shower
  and thunderstorm chances expected Monday night into Tuesday,
  and again Friday into Friday night.

&&

.DISCUSSION...
Issued at 255 PM CDT Sun Jul 6 2025

Rain associated with a short-wave trough was finally moving out of
eastern WI this afternoon, and clouds were gradually clearing.
North to northeast winds were gusting to around 20 mph in eastern
WI. Temperatures ranged from the middle 60s near Lake Michigan to
the 70s and lower 80s inland.

Fog Potential Tonight...High pressure will ridge into the western
Great Lakes tonight, resulting in partly cloudy skies and
decreasing winds. Conditions will be most favorable for fog in
the Wisconsin River Valley (NC/C WI), where boundary layer winds
will diminish to around 5 knots. Farther east, there should be
just enough wind to prevent any significant fog development.
Although patchy dense ground fog is likely, do not anticipate any
need for fog headlines.

Precipitation Trends...Rainfall chances will occur in association
with a couple short-wave and frontal passages this week; mainly
during the late Monday night through Tuesday and Friday through
Friday night periods. Current indications suggest only marginal
instability for both events, so the severe threat is uncertain.
The late week system appears to have a bit more dynamic forcing
and a more moist air mass, with PWATs increasing to 2+ inches in
some areas. Will need to keep an eye out for heavy rainfall
potential Friday into Friday night.

Seasonal temperatures are expected through the extended forecast
period.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1051 PM CDT Sun Jul 6 2025

Mainly VFR conditions are expected through the TAF period. The
exception will be if fog can develop overnight. Chance for
widespread fog remains under 20% with no major change in the 00z
guidance, but with the recent rain, would expect at least some
patchy ground fog to develop overnight across parts of central and
north central WI (especially in/near the Wisconsin River Valley),
where winds are the lightest (under ~5 kts). Have continued with
TEMPO groups between 08z-12z/Mon for fog at RHI/AUW/CWA. Across
eastern WI, there was more rain over the past 24-36 hours, but
winds in the boundary layer are a little stronger (5-10 kts), so
it will be more of a challenge to get fog to form. Will hold off
on any TEMPO groups at GRB/ATW/MTW and monitor trends.

Monday will be dry with light winds. Chances for showers and
storms return Monday night into Tuesday morning. Some elevated
smoke could make for a hazy sky at times through the TAF period.

&&

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

&&

$$

DISCUSSION.....Kieckbusch
AVIATION.......Bersch