Lake Wazeecha, Wisconsin Weather Forecast Discussion

926
FXUS63 KGRB 210709
AFDGRB
Area Forecast Discussion
National Weather Service Green Bay WI
209 AM CDT Sun Sep 21 2025
Forecast discussion for routine morning forecast issuance
.KEY MESSAGES...
- On and off chances for showers and thunderstorms continue today
  through Monday. Best chance for a few strong storms is Monday
  afternoon and evening.
- Patchy areas of fog have developed overnight and will linger
  through mid-mornig before burning off. Another round of fog is
  possible tonight.
&&
.DISCUSSION...
Issued at 207 AM CDT Sun Sep 21 2025
SHORT TERM (Today through Monday afternoon)
Thunderstorms: Scattered light showers continue across eastern
Wisconsin early this morning as a short-wave trough moves to the
east. A second short-wave, currently over eastern North Dakota
and western Minnesota, is expected to arrive this afternoon. Warm
air advection ahead of this wave and a weakly destabilizing
environment with MUCAPE values of 800-1000 J/kg should trigger
showers and thunderstorms this afternoon and evening. While the
risk for stronger storms is low today due to the best forcing
remaining to the west, a marginal severe weather threat exists for
late Monday afternoon, mainly south of Highway 29. A cold front
will be dragged across Wisconsin on Monday by the short-wave as it
moves across the UP. This front, although expected to become
diffuse, may provide enough focused ascent to combine with
increased MUCAPEs of 1000-1200 J/kg and deep layer shear of 25-30
knots to support the development of marginal severe storms. The
primary hazards with any strong storms that develop are hail and
isolated microburst wind gusts.
Flooding Localized flooding is a concern for Monday due to slow
storm motions. However, Precipitable Water (PWAT) values are
expected to decrease from recent levels, dropping to 1.0-1.2
inches which should limit the heavy rain potential.
Dense Fog: Behind this mornings rain, areas of fog have developed
across parts of central and north-central Wisconsin, with a few
pockets of dense fog. This fog is expected to burn off by mid-
morning. Tonight patchy areas of are likely to develop across much
of the region.
LONG TERM (Monday Night through next weekend)
A short-wave trough and its associated surface boundary are
forecast to exit the region Monday night into early Tuesday
morning. A few lingering showers may persist Monday night, but the
area is expected to dry out by mid-Tuesday morning as a surface
high-pressure system builds in from the west and brings in drier
air. Ensemble guidance from various models supports this pattern,
showing continued height rises along the U.S./Canadian border
through the middle of the week, which should keep the forecast
area mostly dry.
The next synoptic feature of note is a surface low that is
progged to develop over the Ozarks during the middle of next week.
This low is then forecast to lift northeast, tracking toward the
eastern Great Lakes region from Thursday into Friday. While some
moisture wrapping around this system could potentially bring a few
showers to the lakeshore late in the week, the primary axis of
better moisture and instability is expected to remain shunted well
to the south of our forecast area.
Temperatures throughout this extended period are expected to
remain steady, holding at or just above normal for this time of
year. The overall pattern appears to favor a relatively tranquil
period with minimal impactful weather.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1147 PM CDT Sat Sep 20 2025
Scattered showers continued in portions of east-central and far
northeast WI late this evening. However, they were not impacting
the east-central WI TAF sites, and should continue to not impact
these sites. Instead, a low deck, with cigs of 100 to 500 ft AGL,
moved into portions of central and north-central WI. Regardless of
these cigs and lower vsbys moving into these areas a bit sooner
than previously forecast, anticipate the cigs and vsbys to
continue to bounce in and out of IFR/LIFR through 13-15z. The
signal continues to look less impressive over the east-central WI
TAF sites, but continued to include TEMPO groups with MVFR/IFR
conditions during early Sunday morning.
Models have lowered the coverage and likelihood of isolated
showers developing Sunday afternoon/evening. But, there is still a
signal for RHI to see some showers, so have included a PROB30 for
rain showers. Depending on how conditions evolve Sunday
afternoon, the mention of showers may need to be added to other
TAF sites.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION.....GK
AVIATION.......Kruk

NWS GRB Office Area Forecast Discussion