Manawa, Wisconsin Weather Forecast Discussion

646
FXUS63 KGRB 212010
AFDGRB
Area Forecast Discussion
National Weather Service Green Bay WI
310 PM CDT Sun Sep 21 2025
Forecast discussion for routine afternoon 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 where quarter size hail and strong wind
  gusts are possible.
- Areas of fog are expected tonight, especially after midnight and
  then linger into Monday morning. The fog may be locally dense
  with the visibility of 1/4 mile possible. The fog may impact the
  morning commute to work or school.
&&
.DISCUSSION...
Issued at 310 PM CDT Sun Sep 21 2025
SHORT TERM (Today through Monday afternoon)
Scattered showers and isolated thunderstorms continued this
afternoon, with a few of them producing brief locally heavy rain.
The showers and storms should diminish and then end around
sunset. Later this evening and overnight, areas of fog will
develop with locally dense fog possible at times. The HREF
was indicating probabilities of 40-70% that the visibility
will drop below one mile tomorrow morning. The probabilities
were pretty similar for 1/4 mile as well. Also overnight,
an upper level disturbance will bring another round of showers
and perhaps a thunderstorm across north-central WI that could
impact the fog. On Monday, scattered thunderstorms are expected
as the upper level disturbance moves over the state. Bufkit
soundings indicated around 1,000 J/KG of CAPE, 0-6 km shear
values around 30 knots to support stronger storms. The
Storm Prediction Center Day 2 outlook has a Marginal Risk of
severe storms, generally south of Highway 29. Will mention
the risk of a severe storm in the Hazardous Weather Outlook.
LONG TERM (Monday Night through next weekend)
Any lingering storms Monday afternoon should come to an end
Monday evening. Overnight, areas of fog are expected. The fog
may be locally dense. Confidence is moderate to high based
on numerical guidance supporting fog. From Wednesday through
Sunday, above normal temperatures are expected. By late
September, the normal high drops into the 60s. NBM probabilities
of highs reaching 70 each day ranged from 40-70% across the north
and 50-80% over the south. The only concern will be Wednesday
into Thursday as the ECMWF has shifted the system northward over
the last few days. May need to add or increase the chance of rain
for this period. Dry conditions should prevail Friday through
Sunday.
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 18Z TAF Issuance
Issued at 1216 PM CDT Sun Sep 21 2025
Isolated to scattered thunderstorms are expected to develop
across the area this afternoon. Based on the meso models,
confidence is low that a storm would move across a TAF site, thus
only went with a PROB30 group to cover the potential for storms
this afternoon. At KRHI, there may be another round of showers
during the evening based on the meso models. Later tonight, fog
and low CIGS (VFR or lower) are expected to develop. HREF
probabilities of the visibility dropping below one mile is
40-70%. If fog does develop, suspect areas of dense fog at times
with a visibility below 1/4 mile. Later tonight, another round
showers and storms will move into north-central Wisconsin and
continue through most of the morning. Thunderstorms will also
be possible. The storms should move into east-central WI by late
morning or afternoon. A few stronger storms with hail and gusty
winds will be possible with the stronger storms. Low clouds and
fog are again possible Monday night into Tuesday morning.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION.....Eckberg
AVIATION.......Eckberg

NWS GRB Office Area Forecast Discussion