631
FXUS63 KGRB 300346
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1046 PM CDT Tue Jul 29 2025

Updated aviation portion for 06Z TAF issuance

.KEY MESSAGES...

- A cold front will move across northeast Wisconsin this evening,
  bringing a chance of showers and thunderstorms, though
  widespread severe weather is not anticipated. A strong storm
  cannot be ruled out.

- Smoke from wildfires to the northwest is expected to spread
  across north-central and northeast Wisconsin tonight through
  Thursday, potentially reducing visibilities at times. An Air
  Quality Advisory is in effect until noon Thursday.

- On Wednesday, light rain is possible for southern portions of the
  forecast area as a convective complex tracks across southern
  Wisconsin.

- From Thursday through early next week, a pattern change will bring
  cooler, drier, and more comfortable air to the region, with the
  next chance of rain arriving Sunday into Monday.

&&

.DISCUSSION...
Issued at 209 PM CDT Tue Jul 29 2025

Short Term...Tonight and Wednesday

Passage of a weak cold front brought some isolated shower activity
to portions of eastern Wisconsin, mainly along the Lake Michigan
shoreline but most of the area did remain dry through the evening.
Any remaining shower activity will quickly diminish through the
early overnight hours, bringing back quiet conditions behind the
cold front.

Following the frontal passage, northerly to northeasterly winds
will bring a significant amount of smoke, both aloft and at the
surface, into the region. This smoke is anticipated to spread
across north-central and northeast Wisconsin from mid-evening
through the overnight hours. Reduced visibilities are possible at
times through Wednesday, given the current lower visibilities
upstream over northern Minnesota and north of Lake Superior.

On Wednesday, a convective complex is forecast to track from west
to east across southern Wisconsin and northern Illinois.
Confidence is increasing (30-60%) that the northern periphery of
this system will affect areas south of Wisconsin Rapids to
Kewaunee from mid to late Wednesday morning through late Wednesday
afternoon. Rainfall amounts are expected to be light, generally
less than a tenth of an inch. Northern Wisconsin should experience
a cooler and less humid day, with high temperatures in the
mid-70s.

Long Term...Wednesday Night Through Tuesday

The latest ensemble means indicate a significant pattern change
across the western Great Lakes for much of this period. Ridging
over northwest Canada is forecast to gradually shift eastward late
this week. Simultaneously, high pressure will build southeastward
and slowly traverse the Great Lakes. This surface high will
introduce an airmass originating from northern Canada,
characterized by 850 mb temperatures approximately 4-5 degrees
Celsius below normal and precipitable water values at 50-60% of
normal.

High temperatures are expected to be near normal, ranging
from the mid-70s to lower 80s. Overnight low temperatures will be
comfortable, generally in the mid-40s to mid-50s. The next chance
of rain will arrive Sunday into Monday, as a low-amplitude
shortwave undercuts the ridge and tracks over the northern
Mississippi Valley. Upper-level wind fields appear typical for
late summer, so severe weather is not anticipated.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1042 PM CDT Tue Jul 29 2025

Smoke will be the initial concern for the area, with near surface
smoke working its way into and across the area tonight through
Wednesday morning. Visibility could drop to MVFR at times from
smoke in the area through the afternoon hours.

Then another larger rainy system will pass to our south which
could bring some rain into portions of central and east-central
Wisconsin during the afternoon. The northern extent of any rain
remains uncertain, so kept only a PROB30 for ATW and MTW. If this
rain pushes further northwards, GRB may also see an inclusion in
future TAF updates. Lowered ceilings some for Wednesday afternoon
as a result as well, but should still remain VFR outside of
showers, which could dip briefly MVFR.

&&

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

&&

$$

DISCUSSION.....MPC/MPC
AVIATION.......Uhlmann