936
FXUS63 KGRB 190234
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
834 PM CST Tue Nov 18 2025

New Information added to update section

.UPDATE...
Issued at 833 PM CST Tue Nov 18 2025

Fog is beginning to form across central and east-central Wisconsin
where snow fell during the day. Airport and local law enforcement
indicated the fog has become dense across some areas. Given skies
continue to clear out, will issue a Dense Fog Advisory for
Portage, Waupaca, Outagamie, Waushara, Winnebago and Calumet
counties where the heaviest snow fell. Will keep a close eye on
observations and expand the Dense Fog Advisory as needed if it
spreads out of these counties.

&&

.KEY MESSAGES...

- Light to moderate snow will exit parts of central and east-
  central Wisconsin by the end of the afternoon. Icy spots may
  develop on untreated roadways this evening as temperatures fall
  below freezing.

- Patchy dense fog will restrict visibilities over parts of
  central and east-central Wisconsin late tonight into Wednesday
  morning. A Dense Fog Advisory has been issued for portions of
  the area.

- Seasonal temperatures with below normal precipitation for the
  rest of the week.

&&

.DISCUSSION...
Issued at 156 PM CST Tue Nov 18 2025

Short Term...Tonight and Wednesday

The latest RAP analysis shows shortwave energy moving into far
southwest Wisconsin early this afternoon. Associated surface low
is moving towards the St. Louis area while high pressure resides
north of Lake Superior. A mid-level deformation zone remains
draped across central to east-central Wisconsin where a band of
moderate precipitation is occurring. This band intensified by late
morning from northern Wood county into Manitowoc county. A report
of 4" was received north of Iola in northwest Waupaca county. The
back edge of the precip is moving across Wood county early this
afternoon which should shift southeast over the next several
hours. This precipitation should exit east-central WI by the end
of the afternoon. The Winter Weather Advisory ends at 3 pm this
afternoon, and will make a last minute decision whether an
extension is warranted for parts of east-central WI. Anticipate
that central WI counties included in the Advisory will be dropped.

There is also some concern exists for icy spots after the snow
ends due to temperatures falling below freezing this evening,
mainly on untreated roads.

A sharp edge to the precipitation exists on the northern flank due
to very dry air from the high pressure system to the north. This
high pressure system will drop south across the area tonight and
linger across the area on Wednesday. Some guidance generates fog
over central to east-central Wisconsin overnight into Wednesday
morning. This looks plausible given the precipitation today, plus
any snow melt that takes place that could augment boundary layer
moisture. Have added fog to the forecast. The signal for fog seems
strongest over central WI, but confidence isn`t the highest due to
the dry air from the high to the north.

Any fog should burn off by mid-morning, which should leave some
mostly sunny skies until late in the day when clouds increase from
the west.

Continued to trend low temperatures colder than the NationalBlend
tonight with lows in the teens and 20s. Highs on Wednesday should
rise into the upper 30s to lower 40s.

Long Term...Wednesday Night Through Tuesday

Over the next week, a split flow pattern will remain present over
the lower 48. Slow moving energy will translate east across the
desert southwest while the northern stream will generally be low
amplitude.

Generally low impact weather is forecast in this pattern. A
northern stream shortwave will push a cold front across the region
on Thursday. There will be a chance of light rain (30-40%) over
mainly far northern Wisconsin from late Wednesday night into
Thursday. The NBM initialized with precip chances further south,
but given the split flow pattern, think this is rather aggressive.

Additional shortwave energy in the northern stream will skirt pass
the region to the north over the weekend into early next week.
While a low precip chance could develop confidence is rather low
on the details given the fast, nearly zonal flow aloft.

Temperatures from Thursday into early next week will generally
range from the upper 30s to upper 40s, which is near to slightly
above normal for this time of the year.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 509 PM CST Tue Nov 18 2025

High pressure will build into the region tonight. Clearing skies
and light winds, combined with boundary layer modification from
today`s precipitation, will create favorable conditions for fog
development. Confidence is increasing for IFR to LIFR visibilities
developing at AUW, CWA, GRB, and ATW generally between 07Z and
15Z Wednesday morning. Lower confidence at RHI due to drier air at
the surface, though patchy fog cannot be ruled out.

Any fog is expected to burn off by mid-morning (14-15Z), leaving
VFR conditions with scattered mid and high clouds for the rest of
the taf period. Looking ahead, MVFR ceilings are expected to
return to the area late on Wednesday afternoon and Wednesday
night.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 8 AM CST Wednesday for WIZ036>038-045-
048-049.
&&

$$

UPDATE.........Kurimski
DISCUSSION.....MPC
AVIATION.......Kurimski