608
FXUS63 KGRB 251204
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
704 AM CDT Tue Aug 25 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Periods of showers and storms today through Wednesday evening.
  Greatest potential (40-60%) for widespread chances overnight.
  Low risk of severe weather, mainly late this evening in north-
  central and central WI.

- Next chance for unsettled weather arrives this weekend.

- Gusty south/southwest winds will generate hazardous conditions
  for small craft and dangerous swimming conditions along Lake
  Michigan this evening through Wednesday morning.

&&

.DISCUSSION...
Issued at 213 AM CDT Tue Aug 25 2026

Precipitation Trends...Periods of showers and thunderstorms are
anticipated from late this morning through Wednesday evening. For
late this morning into this afternoon, a weak 850mb jet and
increasing WAA will drive the potential for isolated showers and
storms (25-35%) mainly across the Northwoods. Later this evening
through late tonight, chances for showers and storms increase to 40-
60% spreading across the entire forecast area as a cold front sweeps
across the area. During the late evening (after 9 PM), there appears
to be a small window for a few stronger storms to move into north-
central and central WI. Surface instability and deep-layer shear
will be greatest northwest of the area and will be waning as the
storms move eastward into the forecast area. However, cannot rule
out the potential for the ongoing convection to produce damaging
wind gusts and hail in central and north-central WI before
weakening. The strong/severe storm potential will decrease a few
hours after 9 PM as the storms become elevated. Additional showers
and non-severe storms are possible Wednesday, mainly during the
afternoon, as the surface cold front`s mid-level shortwave trough
moves overhead. By Wednesday evening, probabilities for 0.50 inch or
more of precip range between roughly 20-40% mainly across the
Northwoods and Door County, with less than 10% elsewhere, but would
still expect a few localized areas to receive closer to an inch of
rain under the stronger convection.

After Wednesday, dry weather is anticipated for the remainder of the
work week with the next chances for showers and storms arriving
sometime this weekend. Will need to monitor for the severe weather
potential as the pattern may favor this solution on one of the days
somewhere across the Midwest, but there are timing and placement
differences that will need to be resolved until then.

Temperatures...Throughout the week and into the weekend,
temperatures, both highs and lows, will hover around normal. Highs
will mainly be in the 70s to low 80s, with lows generally in the 50s
to low 60s, but locations across the Northwoods could see lows in
the 40s Thursday night into Friday morning.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 704 AM CDT Tue Aug 25 2026

Mainly VFR conditions with high and mid-level clouds prevailed
across the region this morning. Patchy ground fog was also
reported in a few spots. Taking away the patchy ground fog,
expect these conditions to continue through at least this evening.
Hi-res models indicate scattered showers developing in the late
afternoon, most likely impacting the RHI TAF site, but determining
the exact timing and placement of these showers is rather
difficult, so kept a PROB30 after 20z Tue for now. A greater
chance of showers and storms arrives at the RHI/AUW/CWA TAF sites
between 02z and 06z Wed. Gusty winds and IFR vsbys will be
possible in the heavier showers/storms. The showers/storms will
be weakening as they track southeast over the GRB/ATW/MTW TAF
sites, so have included PROB30 groups for -SHRA for now. Following
the precip, cigs will drop to IFR/MVFR from northwest to
southeast beginning at RHI around 06z Wed.

Southwest winds will increase this afternoon with gusts of 15-20
kts. While the gusts will decrease in central and north-central
WI, the gusts will continue across the east-central WI TAF sites
overnight.

&&

.MARINE...
Issued at 213 AM CDT Tue Aug 25 2026

A period of persistent south/southwest winds is expected this
afternoon into Wednesday. Winds will gust to 25 kts, with waves
building to 2 to 4 ft with some 5 foot waves possible mainly along
the Lake Michigan nearshore waters. As a result, a Small Craft
Advisory has been issued from 6 PM this evening to 4 AM Wednesday
from Sheboygan to Sturgeon Bay, and 8 PM this evening to 11 AM
Wednesday from Sturgeon Bay to Washington Island. These conditions
will also result in a high swim risk at Lake Michigan beaches.
Beach Hazards Statements have been issued for Manitowoc, Kewaunee,
and Door County.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Beach Hazards Statement from this evening through Wednesday
morning for WIZ022.

Beach Hazards Statement from 6 PM CDT this evening through late
tonight for WIZ040-050.
&&

$$

DISCUSSION.....Kruk
AVIATION.......Kruk
MARINE.........Kruk

NWS GRB Office Area Forecast Discussion