Green Bay, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

082
FXUS63 KGRB 042330
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
630 PM CDT Sat Jul 4 2026

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- Isolated showers and thunderstorms are expected this afternoon
  and evening, mainly across central and north-central WI.

- Seasonal summer temperatures are expected for the holiday
  weekend and into next week.

- Dry conditions early next week, with shower and thunderstorm
  chances (50-80%) returning mid-week.

&&

.DISCUSSION...
Issued at 233 PM CDT Sat Jul 4 2026

This afternoon through tonight...very little shower activity so
far this afternoon as clouds and northeast winds have keep the
atmosphere more stable, with the higher dewpoints and instability
residing to our south/west. Getting some good insolation how
across portions of central WI, where MLCAPEs are expected to climb
to 1500 J/kg during peak heating. This, combined with an
approaching weak shortwave, should kick off at least isolated
showers and a couple storms across central and north-central WI
late this afternoon and early evening. CAMs have continued to
trend downward with coverage, with better chances to our
west/south. Will carry 15-30% PoPs to cover the shower/storm
threat. With little deep-layer shear, any storm would be more
pluse-like and a slow mover, which could produce locally heavy
rain and brief gusty winds. Further north/east, the prevailing
north/northeast winds and limited instability should keep
conditions dry. The shower/storm activity will come to an end this
evening as daytime instability wanes after sunset. A little area
of moisture/elevated CAPE is forecast to advect in from Lower
Michigan overnight, which could trigger a shower over east-central
WI, but no impacts are expected and will hold PoPs under 15.

Some fog and low clouds may linger on/near Lake Michigan, mainly
south of Kewaunee this afternoon into tonight, where the higher
dewpoints reside. But with the drier northeast winds prevailing,
think the thicker, more widespread fog will stay over southern
Lake Michigan.

For Sunday...the weak mid-level shortwave/trough will reside over
the area, but with less instability, persistent northeast winds
ushering in drier air, and CAMs backing off on coverage, looks
like most spots will stay dry. Can`t rule out a stray shower west
of a Rhinelander to Wausau line, so will have some 15% PoPs there.

Next Week...models continue show upper-level ridging residing
over the area for Monday through Tuesday morning. This will result
in dry conditions for Monday and potentially through most of
Tuesday, but some afternoon showers possible over northern WI
Tuesday afternoon. The ridge breaks down as a shortwave and low
pressure system approach, with chances (50-80%) for widespread
showers and storms returning mid-week. Long range global ensembles
do show instability typical of early July during this time making
stronger storms possible; however, there is no signal of a higher
end severe event within the statistical suite of guidance.

Temperatures...Seasonable temperatures are expected Sunday with
highs ranging from the upper 70s to low 80s. Dewpoints will drop
into the 50s and low 60s on Sunday, making for a pretty pleasant
summer day. Temperatures look to be in to upper 70s and 80s for
most of the week, with dewpoints slowly climbing through mid-week.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 436 PM CDT Sat Jul 4 2026

Conditions have lifted to VFR across the forecast area as of this
evening, though borderline daytime cu field remains. Otherwise,
mid and high clouds will continue to spread across the region
through Sunday. SCT showers and isolated storms remain possible
through this evening, mainly in/near the central and north-central
sites, though confidence remains low as to whether a shower or
storm will directly impact a terminal. Regardless, have retained
PROB30 mention of -SHRA at AUW, CWA, and RHI for the first few
hours of the TAF period. No drops in flight category are expected
with any shower or storm activity. Will continue to monitor the
potential for lake fog backbuilding into MTW late tonight into
early Sunday morning, though confidence was low enough to withhold
vsby reductions from the TAF.

Winds will continue to become light and variable overnight,
becoming east/northeasterly by Sunday morning. Winds should remain
under 10 knots throughout the TAF period.

&&

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

&&

$$

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