Appleton, Wisconsin Weather Forecast Discussion

411
FXUS63 KGRB 150850
AFDGRB
Area Forecast Discussion
National Weather Service Green Bay WI
350 AM CDT Mon Sep 15 2025
Forecast discussion for routine morning forecast issuance
.KEY MESSAGES...
- Patchy dense fog will impact travel across far northeast and
  eastern WI early this morning.
- Mainly dry through Tuesday night, with a chance of showers and
  thunderstorms returning Wednesday into Thursday.
- Temperatures about 10 to 15 degrees above normal through mid-
  week, with a return to near normal conditions expected from
  Friday into the weekend.
&&
.DISCUSSION...
Issued at 350 AM CDT Mon Sep 15 2025
Fog Trends: Clear skies and light winds have allowed patchy fog
to develop in far northeast WI, and near the bay and lakeshore,
where boundary layer winds were lightest early this morning. Have
seen a few observations briefly drop to 1/4sm, but given the
patchy nature of the fog, opted to just issue a Special Weather
Statement to cover localized travel impacts for the morning
commute. The fog should mix out by 14z. Fog may redevelop again
late tonight, with models focusing primarily on far northeast WI.
Precipitation Trends: Dry weather continues early this week as
strong upper level ridging persists, and high pressure over Quebec
ridges into NE WI. A chance of showers and storms arrives in the
northwest part of the forecast area Wednesday afternoon as the
upper ridges flattens and a cold front sags south toward the
area. This front will move through the forecast area Wednesday
night into Thursday morning, and continue to bring a chance of
showers and thunderstorms. A break in the precipitation is
expected Thursday night into Friday night, as a SE-NW oriented
upper ridge sets up over the region. The ridge shifts northeast
late Friday night into Saturday, as an upper low lifts into the
western Great Lakes. This system should bring showers through the
weekend.
Temperature Trends: Temperatures will remain well above normal
through mid-week, with highs running 10 to 15 degrees above
normal. A post-frontal cool down is expected late in the week,
with highs dropping back to normal from Friday into the weekend.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1047 PM CDT Sun Sep 14 2025
VFR conditions will prevail late this evening, then attention
will turn to the low cloud and fog potential overnight into
Monday morning. Conditions not as favorable as last night for
widespread clouds/fog. Latest SREF/HREF probabilities have trended
down, now in the 40-60% for VSBY under a mile over far northeast
WI, with lower probabilities under 40% at the TAF sites. Keeping
some fog still seems warranted with the light winds and clear
skies, so will continue to include some MVFR fog at GRB/ATW. Will
keep a lower VSBY in a TEMPO group at RHI, where ground fog is a
little more likely. Will not include fog at AUW/CWA as
probabilities are lowest in this area, but can`t rule out a
little ground fog early Monday morning. Finally, some lake fog may
impact MTW. Will need to monitor fog trends and adjust as needed
through the night.
Any fog will burn off/lift by 13-14z Monday, with VFR conditions
expected the rest of the day. Winds will be light mainly out of
the southeast/east overnight, then increase to around 10 kts on
Monday. LLWS is possible overnight across north central WI as
winds at 1000 ft will be ~25 kts.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION.....Kieckbusch
AVIATION.......Bersch

NWS GRB Office Area Forecast Discussion