099
FXUS63 KGRB 110355
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1055 PM CDT Mon Aug 10 2026

Updated aviation portion for 06Z TAF issuance

.KEY MESSAGES...

- Highs in the 80s through Wednesday, then slightly cooler late
  this week into the weekend.

- Potential for rounds of showers and storms late tonight through
  middle of the week. At this time, risk of severe storms is low.

&&

.DISCUSSION...
Issued at 103 PM CDT Mon Aug 10 2026

Fog potential tonight...

Some patchy fog may develop across eastern Wisconsin overnight
with light winds and mostly clear skies. Models hint that fog
development would not be as ubiquitous or as dense as this
morning.

Shower and storm chances (15-30%) return late tonight through
Wednesday...

Showers and storms developing this evening over the Dakotas
forecast to produce shortwave/upper jet that shifts east toward
Wisconsin late tonight. Gradient of instability from MN to
southern WI, as is the stronger convergence with LLJ. Even so,
with the wave and elevated instability farther north, cannot rule
out some showers and storms on Tuesday morning, with perhaps
slight boost in coverage farther north during peak heating of
afternoon as MLCAPEs increase over 1000J/kg. Effective shear over
40 kts would support stronger storm if convection develops. SPC
does keep the marginal risk for severe farther south near the more
persistent frontal boundary/highest instability.

Rain chances (30-50%) continues Tuesday night into Wednesday as
another shortwave moves through the region and the front remains
close enough to our area. Similar to expectations for late tonight
and Tuesday, appears better signal for severe remains south.
However, late Tuesday night through Wednesday, there is stronger
forcing farther north and sufficient instability. Seems like this
time frame may hold the greatest chances for some stronger storms
over our area, especially if things slow a bit and these factors
catch up to at least the beginning of peak heating on Wednesday.
Machine learning progs show a weak "bump" in severe probs to
5-15% for Wednesday after a relative minimum in severe potential
earlier in the week.

Dry and cooler conditions are then expected late this week, then
chances for rain (30-60%) return for the weekend...

High pressure builds in across the area Wednesday night through
Friday, pushing the front and lingering instability south and
generally keeping the area dry through the rest of the week. Highs
will settle into the 70s regionwide. The high eventually shifts
east, allowing for the chance for showers and thunderstorms to
return to the area Friday night into the weekend. Looking at the
entire weekend it appears Sunday would be the best chance out of
the two days to be dry.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1055 PM CDT Mon Aug 10 2026

Fog will be the main aviation concern overnight, with dense fog
expected at times overnight along the shoreline of Lake Michigan
which will impact MTW. How far this fog moves inland remains
uncertain, but included a mention for ATW and GRB, where
dewpoints remained however during the day. Any fog along the
lakeshore will be IFR to LIFR through the night. Some patchy fog
may also briefly enter central Wisconsin, but confidence and
spread were considered too low to include at this time.

An active weather system will pass south of the area late
overnight into Tuesday morning, which could bring some brief rain
or storms into our area. The northern extent of any overnight
system is still fairly uncertain, so left it to a PROB30 group in
ATW and MTW for now.

After the initial rain Monday, any lingering fog will also
dissipate, bringing back light winds across the region. Early
signs point to a few showers in the evening, which may need
inclusion in later TAF periods, but would expect predominantly
good flying conditions across the area Tuesday afternoon and
evening.

&&

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

&&

$$

DISCUSSION.....Kurimski
AVIATION.......Uhlmann

NWS GRB Office Area Forecast Discussion