847
FXUS63 KGRB 212332
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
632 PM CDT Tue Jul 21 2026

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- Scattered light showers ending by late afternoon and breezy
  winds subsiding toward sunset. Small craft advisories are in
  effect through early Wednesday morning.

- Comfortable and quiet conditions through Friday, followed by
  increasing heat, humidity, and thunderstorm chances (30 to 50
  percent) over the weekend.

&&

.DISCUSSION...
Issued at 218 PM CDT Tue Jul 21 2026

A subtle west to east sfc trough is moving swd across the area
with a wind shift from nwly to more nly expected. Scattered
light showers are ahead of and along the trough with drier air
and isolated showers behind the trough. The cold advection
will continue tnt as the 992 mb low just south of James Bay
lifts newd into north central Quebec through tomorrow. Cloud
cover will gradually clear through the evening with the loss of
heating and the arrival of drier air. Low temps in the 40s are
forecast for ne WI with lower to middle 50s over the Fox Valley.

On Wednesday, a shortwave trough will move across the nrn Great
Lakes to srn Ontario, while high pressure will track from the
nrn Great Plains to sw WI and ne IA. Lingering cool air aloft
will lead to broken cloud cover for a time on Wed, with high
temps mainly in the lower to middle 70s.

A relatively dry airmass and gradually warming temperatures back
to near normal are anticipated for Thu-Fri as high pressure
tracks from nrn IL to the lower Great Lakes.

Shower and thunderstorm chances return to the forecast for the
weekend and early next week. Nwly flow aloft will continue with
embedded shortwave troughs. There may be a couple low pressure
areas that track across srn Canada or the nrn USA and affect ne
WI and east central WI. High temperatures in the 80s are
forecast with increasing relative humidity.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 620 PM CDT Tue Jul 21 2026

A deck of BKN to OVC at 060 over the north woods is anticipated
to dissipate through sunset as northerly flow slowly transits it
south. Gusty north-northwesterly flow will gradually subside into
the overnight hours, remaining northerly into Wednesday. Primarily
VFR conditions should prevail for the 00Z TAF cycle.

.KOSH...

Gusty north-northeasterly winds to 25kts are anticipated for the
coming hours, gradually diminishing following sunset. Clouds
lift and clear overnight, with northerly flow and few to scattered
cu expected Wednesday. VFR conditions should prevail.

&&

.MARINE...
Issued at 218 PM CDT Tue Jul 21 2026

Breezy nly winds will continue for much of the night with the
Small Craft Advisory in effect until 4 AM CDT Wed. Light to
modest nnwly winds are expected on Wed with lake breeze
development possible by mid to late afternoon. Light wly winds
Thu AM are expected to become modest sly winds for Thu
afternoon.

&&

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

&&

$$

DISCUSSION.....MG
AVIATION.......HEK
MARINE.........MG

NWS GRB Office Area Forecast Discussion