631
FXUS63 KGRB 011912
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
212 PM CDT Fri Aug 1 2025

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Smoke from Canadian wildfires will result in poor air quality
  and reduced visibilities at times through Saturday morning. An
  Air Quality Advisory is currently in effect until noon Saturday.

- Patchy fog may restrict visibilities for motorists at times
  early Saturday morning.

- Dry weather, cool nights, warm days and low humidity are
  expected through the weekend. The chance of rain is not expected
  to return until the Wednesday and Thursday of next week (15-30%
  chance).

&&

.DISCUSSION...
Issued at 210 PM CDT Fri Aug 1 2025

Short Term...Tonight and Saturday

High pressure is centered across the northern Mississippi Valley
and western Great Lakes early this afternoon. Other than fair-
weather convective clouds between 5000-6000 ft, skies are hazy
from smoke across the forecast area. Widespread reduced
visibilities are reported across northern Minnesota, Ontario, the
Lake Superior region, and far northern Wisconsin, down to 3 to 5
miles. Forecast concerns are few, and include smoke trends and the
potential for fog.

An Air Quality Alert is in effect until noon Saturday. Surface-
based smoke is forecast to rotate southward across the area late
this afternoon and evening and continue through much of Saturday.
The potential for the greatest impacts are roughly from about 5
pm this afternoon through about 8 am Saturday morning according
to the HRRR and RAP models. Confidence for surface-based impacts
from smoke is lowest over central Wisconsin and highest over far
northern Wisconsin.

Patchy ground fog is possible late tonight between about 2 am and
7 am. Confidence in the coverage of the fog is on the lower side
because crossover temperatures are below the forecast low
temperatures. At the very least, the cold spots of north-central
Wisconsin, including the sandy soil areas, will likely see ground
fog. Low temperatures tonight remained on the cold side of
guidance, so the previous forecast was blended with MOS
statistical data. Minimum temperatures in the lower to middle 40s
are possible in the sandy soil areas of far northern Wisconsin.

Long Term...Saturday Night Through Friday

Relatively quiet and seasonal weather remains forecast across
northeast Wisconsin. An upper ridge will be slowly migrating east
across central Canada, while troughing digs into the mid-
Mississippi Valley through early next week. Between these
features, the chance of rain will be low, less than 10 percent.
Around mid-week, the ensemble means point toward a weakness at
500mb moving across the region. At the same time, a more unstable
(but nothing drastic) airmass starts to build into the region.
This could lead to unsettled weather on Wednesday and Thursday of
next week.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1202 PM CDT Fri Aug 1 2025

Relatively good flying weather is expected through the TAF period.

Fair weather cumulus remains on track to develop this afternoon around
6,000 feet before rising to around 8,000 over north-central and
far northeast WI. Fair weather cumulus will develop again late
Saturday morning and afternoon.

Patchy ground fog is expected between 07-12z Saturday, probably
impacting much of north-central and far northeast WI. Confidence
is low whether the ground fog will impact the Fox Valley and
lakeshore areas.

Lastly, surface smoke will drop visibilities at times to MVFR for
much of the TAF period. Confidence is highest that MVFR
visibilities will occur over north-central and far northeast WI.
But some potential that the Fox Valley and Lakeshore areas will be
impacted between 22z Fri thru 13z Sat. Awfully difficult to case
reduced visibilities in smoke so will monitor and amend as
necessary.

&&

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

&&

$$

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

NWS GRB Office Area Forecast Discussion