579
FXUS63 KGRB 221136
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
636 AM CDT Sat Aug 22 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Isolated to scattered showers and storms (30-50% chance)
  expected over north-central to eastern WI, mainly in the
  afternoon. A strong storm with gusty winds and hail is possible.

- Dry weather returns Sunday and Monday, with a period of
  unsettled weather arriving for the middle of next week.

- Slightly below normal temps this weekend, then a return to near
  normal readings for most of next week.

&&

.DISCUSSION...
Issued at 126 AM CDT Sat Aug 22 2026

This Weekend...Recent rainfall, mostly clear skies and light
winds has led to some patchy ground fog development, especially
across northern WI. Some clouds moving in should help keep the
fog in check, but at least some patchy fog will continue early
this morning, then burn off after sunrise. Northwest, cyclonic
flow will prevail across the Great Lakes through the weekend with
a couple shortwaves moving with this flow bringing chances for a
few showers and storms. The first weak shortwave arrives this
morning, bringing a stray shower or sprinkle across far northern
WI. A second shortwave will dive across northeast WI this
afternoon, bringing isolated to scattered showers and storms
(20-50% chance) mainly to far northern and eastern WI. While weak
deep layer shear (under ~25 kts) will limit overall organization
of the storms and the severe threat, SBCAPE of up to ~1200 J/kg,
inverted-V soundings and very steep low-level lapse rates will
promote some gustier winds and small hail in the stronger
showers/storms. Northwest winds will increase to 15 to 25 mph this
morning and afternoon.

Surface high pressure and drier air will keep the area dry tonight
into Sunday. Northwest winds will be a little lighter on Sunday,
but still gust to 20 mph.

Next Week...Dry weather continues on Monday, then another
shortwave trough is forecast to move across the region late
Tuesday into Wednesday, bringing the next chance (40-65%) for
showers and thunderstorms. Instability appears modest with this
mid-week feature, keeping severe probabilities low.

Temperatures...Temps this weekend will dip a little below normal
as northwest flow prevails, with highs mainly in the 70s to near
80 (with a few upper 60s over far northern WI on Sunday). A couple
chilly nights are in store this weekend, especially across
northern WI where lows will dip into the upper 30s to low 40s.
Temps nudge back to near or slightly above normal for much of next
week with highs mainly in the mid 70s to low 80s.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 636 AM CDT Sat Aug 22 2026

Patchy ground fog will burn off shortly after sunrise, with some
other mid clouds moving across eastern WI. While a few lower
clouds could move into far north-central WI this morning, expect
low end VFR clouds to build with daytime heating in the 15-16Z
timeframe. Isolated showers should develop over far northeast WI
in the 20-00Z timeframe, but coverage will be limited, so have
kept the PROB30 going at GRB/MTW/ATW. A stray storm is also
possible, but chances are too low to include. Only a few lingering
clouds are expected after dark and into tonight.

Northwest winds will increase this morning and become a bit
breezy, with gusts to 20 kts in the late morning and afternoon,
then easing to under 10 kts after sunset.

&&

.MARINE...
Issued at 126 AM CDT Sat Aug 22 2026

Northwest winds of 10-20 kts are expected this weekend. Gusts to
25 kts will be possible, mainly near Death`s Door. HREF 10m gust
ensemble mean and max bring 25 kt winds right to Washington
Island, but keep the stronger winds towards northern Lake
Michigan. Due to the very small area and marginal winds, will hold
off on issuing a Small Craft Advisory.

Offshore winds will limit waves to 1 to 3 ft for most spots on the
bay and nearshore waters, with any 3-4 foot waves staying in the
open waters.

&&

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

&&

$$

DISCUSSION.....Bersch
AVIATION.......Bersch
MARINE.........Bersch

NWS GRB Office Area Forecast Discussion