624
FXUS63 KGRB 101804
AFDGRB

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

Forecast discussion for routine afternoon forecast 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 18Z TAF Issuance
Issued at 1203 PM CDT Mon Aug 10 2026

Fair weather cumulus clouds will continue to develop this
afternoon with daytime heating. Currently bases range from
015-025 across central and east-central Wisconsin with higher dew
points, to 4-5k ft across north-central Wisconsin given the lower
dew points. Bases should slowly rise to 3-4k ft across central and
east-central Wisconsin this afternoon as temperatures rise. These
clouds should then dissipate shortly after sunset with the loss
of daytime heating. Some patchy fog could develop overnight across
east- central Wisconsin, reducing VSBYs to MVFR at times at
GRB/ATW/MTW. Higher up in the atmosphere a plume of smoke will
continue to stream in above the lower clouds. Winds will be light
through the TAF period.

Chances for showers and some storms occur on Tuesday morning along
a frontal boundary. However, the best chance for storms appears to
be further south closer to the actual boundary. Therefore, will
not include precipitation at the TAF sites as chances are too low
with this forecast issuance. Occasional MVFR conditions may occur
with the showers.

&&

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

&&

$$

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

NWS GRB Office Area Forecast Discussion