346
FXUS63 KGRB 232319
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
619 PM CDT Sun Aug 23 2026

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- Dry through Monday, with rain chances (50-80%) Tuesday
  afternoon through Wednesday evening. The risk of widespread
  severe weather is low.

- Chilly with lows into the 30s north-central WI tonight.
  Otherwise temperatures most of this week will be near or
  slightly above normal.

&&

.DISCUSSION...
Issued at 1234 PM CDT Sun Aug 23 2026

Near term through Monday...NW flow persists to the west of deep
troughing over the central and eastern Great Lakes. Cooler air
aloft the warmer lakes and daytime heating will result in
blossoming cu this afternoon. Moisture appears too shallow to
conjure up any showers, though a few sprinkles could occur.
Northern Door most favored for those. Northwest winds will be
gusty again this afternoon, but will back off quickly this
evening. As winds become light and skies clear, temps will drop
quickly, with mid 30s in favored cold spots of north-central WI,
low-mid 40s central WI into far northeast WI, and upper 40s to
near 50 from the Fox Valley to the lakeshore. Some very patchy
ground fog will be possible late tonight into Monday morning,
especially across central and northern WI. It could be cool enough
for sheltered areas in the far north to see some brief patchy
frost late tonight. Mostly sunny on Monday with light winds.

Showers and some storms Tuesday afternoon through Wednesday
evening...Sharp shortwave trough with cold front drop into
northern MN Tuesday afternoon before shifting across WI and MI
through Wednesday. Pooling instability along the front late
Tuesday may allow a small severe risk into far northwest portions
of cwa very late Tuesday afternoon into Tuesday evening. Various
ML sources point to this, but even so, stronger signal stays
farther into northwest WI and northern MN. That said, showers
and storms will probably not completely die off later Tuesday
night as they move east given a persistent LLJ and some elevated
instability with the stronger system. Does appear that models are
coming into better agreement with faster fropa on Wednesday,
pushing the primary severe risk farther east. Enough cool air
aloft with the trough to result in chance pops northeast and
eastern WI through peak heating on Wednesday. Thus, suppose an
isolated strong to severe storm is not off the table. Chances for
showers and storms on Thursday have decreased as core of upper
trough and cooler air aloft has shifted farther north. Pops for
Thursday now sitting at less than 10 percent.

Extended...Next chances for showers and storms (20-40%) eases
back into the area from the southwest for the weekend as flow
aloft becomes more zonal. Early look, but signal for greatest
instability and severe/heavy rain potential remains southwest
plains to the upper mississippi river valley.

Temperatures...After the chilly conditions tonight, temperatures
the rest of the week look to be near normal or slightly above
normal. Warmest days with highs in the low-mid 80s would be
Tuesday and/or Wednesday ahead of and near the frontal boundary
moving through. Warmest night in the 60s much of the area will be
Tuesday night with clouds, showers and some wind. Lows could drop
back into the 40s again late this week over the north.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 619 PM CDT Sun Aug 23 2026

No significant changes to the previous forecast.

Other than patchy ground fog for central and north-central WI
late tonight, plan on VFR conditions through the TAF period.
Higher based cumulus clouds will clear out early this evening,
with just wispy cirrus at times for the rest of the night. Less
fair weather clouds are expected on Monday, but increased coverage
a bit in this issuance based on obs upstream into the few-sct
range. Cloud bases will likely remain above 5-6 kft.

Northwest winds will subside early this evening becoming 5 kts or
less overnight. With high pressure centered across the region, winds
on Monday will be light, topping out at 5 to 10 kts during the
afternoon.

&&

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

&&

$$

DISCUSSION.....JLA
AVIATION.......MPC

NWS GRB Office Area Forecast Discussion