515
FXUS63 KGRB 081130
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
630 AM CDT Sat Aug 8 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Several rounds of showers and storms are expected from Sunday
  through the middle of next week, though confidence in storm
  timing and severity remains low.

- Near normal temperatures in the low 80s through the middle of
  next week, with a cooling trend by the end of the week.

&&

.DISCUSSION...
Issued at 1243 AM CDT Sat Aug 8 2026

Expect dry conditions today as weak high pressure shifts east and
more stable air filters in behind the front, with fair weather cu
field developing by late morning. Gradient winds increase
slightly out of the northwest this afternoon, with gusts to 20 mph
possible across the forecast area.

Rain/storm chances... Prior forecasts remain on track as prevailing
northwest flow containing several embedded shortwaves brings
periodic chances for rain/storms through the better part of next
week. Greatest opportunity for heavy rain and storms look to be
Sunday afternoon into Monday as surface low crosses the upper
Mississippi Valley, though severe chances remain nebulous. Better
jet dynamics remain off to our south during this time, and
environment looks relatively capped from around 850 to 700 mb up
into northeast Wisconsin. Regarding heavy rainfall potential, NBM
probabilistic guidance only shows a 10 to 20% chance for receiving
1" of rain across our southern two tiers of counties through
Sunday. However, timing of the boundary will play a large role in
whether or not we can get excessive rain, as some long-range
models hint that the front might stall out over southern
Minnesota into central Wisconsin. In this case, we would mostly
rely on training storms to get heavy rain across portions of
central to east-central Wisconsin. This is represented in WPC Day
3 ERO with a marginal risk south of Hwy 29 and a slight risk just
to our south.

Extended... Temperatures to read generally in the low 80s through
mid-week as upper flow flattens out and weakens. Signal for a
cooler and drier pattern shift then exists late next week as
polar airmass builds to the north and is transported south via
troughing regime. Highs will fall into the 70s for most during
this time.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 615 AM CDT Sat Aug 8 2026

VFR conditions prevail through Sunday morning as weak high
pressure centers itself over the Great Lakes. SCT fair weather cu
with bases at around 4 to 5k ft should begin popping over most of
the area by around 15 to 16Z, lifting to around 6 to 8k ft by late
afternoon. Northwest winds will increase and back to
west/southwesterly by this evening, with gusts to 20 knots
possible at all terminals. Rain/storm chances arrive from the west
just beyond the TAF period.

&&

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

&&

$$

DISCUSSION.....Goodin
AVIATION.......Goodin

NWS GRB Office Area Forecast Discussion