305
FXUS63 KGRB 242338
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
638 PM CDT Mon Aug 24 2026

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- Shower/storm chances (40-60%) at times Tuesday afternoon.
  Additional shower/storm chances overnight into Wednesday
  (50-80%). Low risk of severe weather, mainly Tuesday
  evening/night.

- Next chance for unsettled weather arrives over the weekend.

&&

.DISCUSSION...
Issued at 142 PM CDT Mon Aug 24 2026

This afternoon through tonight...
Fairly quiet conditions are expected through the near term period
under high pressure conditions and light winds. Skies will remain
fairly clear but will have some high clouds move through during
the evening to overnight. As winds drop off overnight, some patchy
ground fog may be possible again at times, but expect impacts to
be minimal.

Active Weather Tuesday into Wednesday...
A fast moving shortwave will drop through the region Tuesday
evening followed shortly by a cold front overnight, bringing with
them active weather through the first half of Wednesday. Ahead of
these features, daytime heating ahead could still produce a few
showers, but would expect the focus to be later in the day so
kept a 20-40% chance early. As the shortwave drops through in the
evening, brought some higher chances (50-70%) with the focus being
along the Upper Peninsula border further north. This period will
be the one to watch for any stronger storm potential as surface
instability and shear should suffice for organized convection,
with large hail and damaging winds as the main threats. The
better parameters all align to our northwest, so any stronger
storms should form upstream before slowly working their way
eastwards. As of this forecast issuance, the Marginal Risk area
expands into western Vilas and Oneida counties so storm will still
need watching to see if they hold together. If the low level jet
and surface instability prove more robust in upcoming forecasts,
could see the risk area expand another county or two eastwards
for the evening period. The cold front then arrives overnight,
bringing more widespread rainfall across the whole area (60-80%
chance). The overnight timing will not favor any stronger storms,
with any rain and thunder likely remaining elevated. Although
severe/strong storms aren`t expected, some thunder could still mix
in at times. Probability of exceeding half an inch of rainfall
remains around 50%, mainly for northern Wisconsin, but would still
expect a few localized areas to get closer to an inch of rain
under the stronger convection. The cold front will still be
pushing across the region Wednesday morning, so some precipitation
will still be in place across eastern Wisconsin, but areas
further west will likely already see dry conditions.

Rest of the Forecast...
Another extended period of dry conditions is expected for the
region for the rest of the work week. No active weather is
expected until the broad ridge over southwestern CONUS shifts
eastwards enough to bring a few shortwaves across the northern
edge into our area. Current forecast doesn`t bring the first of
these through the early until early Saturday. Early look at severe
potential keeps the stronger weather to our south, but this will
need monitoring as well as we get closer to the weekend.

Temperatures will change little over the work week, with highs in
the upper 70s to lower 80s during the afternoon, and lows in the
middle to upper 50s (a few lower 60s overnight). The Midwest time
of year you may want a light sweater in the morning and wish you
didn`t have it with you by the afternoon.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 638 PM CDT Mon Aug 24 2026

High pressure will remain over the region tonight. Mainly VFR
conditions are expected with only mid and high clouds present
above 12 kft. Patchy ground fog is possible over far northeast WI,
but probabilities of impacts at the TAF terminals is very low.

Clouds increase on Tuesday as a warm and more humid airmass moves
in ahead of a cold front. Ceilings should generally remain above
3.5 to 4 kft, but broken conditions are likely at times. Guidance
produces scattered showers at times, mainly impacting far northern
WI, including RHI. Timing of these showers is rather difficult to
pin point, but added a prob30 at RHI after 20Z Tue. Timing will
need to get refined in later forecasts.

Southwest winds will increase on Tue with gusts 15-20 kts in the
afternoon.

Outlook:  Thunderstorms are expected after 00Z Wed, which could
impact the RHI, AUW, CWA terminals.

&&

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

&&

$$

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

NWS GRB Office Area Forecast Discussion