640
FXUS63 KGRB 191726
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1126 AM CST Wed Nov 19 2025

Updated aviation portion for 18Z TAF issuance

.UPDATE...
Issued at 653 AM CST Wed Nov 19 2025

Cancelled the Dense Fog Advisory for Shawano and Waupaca counties.
There has been improvement in vsbys in many other counties, but
suspect there are pockets of dense fog/poor vsbys in most of the
remaining counties. Satellite is being masked by high clouds, so
don`t have a good of a view of the fog/stratus coverage anymore.

&&

.KEY MESSAGES...

- Patchy light rain, possibly briefly mixed with light snow or
  light freezing rain, across northern Wisconsin late tonight
  into early Thursday morning.

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

&&

.DISCUSSION...
Issued at 346 AM CST Wed Nov 19 2025

Have expanded the Dense Fog Advisory into Lincoln and Langlade
counties in north central WI, and Manitowoc County in east
central WI. Also extended the expiration to 15z/Wed. Fog is
patchy across parts of the advisory area, but did not remove any
counties, as fog will probably fill in a bit toward sunrise.
Satellite/observations/web cams showed the worst conditions
occurring in the Fox Valley (including the Hwy 41 corridor from
Green Bay to Oshkosh) and the Wisconsin River Valley (including
Hwy 39/51 from Portage County north into Lincoln County). Fog and
low stratus was starting to work its way into the western parts of
Oneida/Vilas counties, so will need to watch trends there for
possible headline expansion.

The fog should mix out by mid-morning, followed by increasing high
clouds. A large area of low clouds situated southwest of the
forecast area will start to work its way into the southwest part
of the forecast area late in the day. High temperatures will be in
the upper 30s and lower 40s.

A weak cold front and low-amplitude short-wave will approach the
forecast area late tonight, then move through Thursday into
Thursday evening. This looks to be another moisture-starved
system, with the best saturation occurring across far northern WI.
Will only carry chance pops across northern WI, though some
neighboring offices feel enough low-level saturation will occur
for some drizzle farther south. Have kept the mention of drizzle
out of the forecast for now, as timesections don`t show much (if
any) lift in the saturated layer. Precipitation type across
northern WI should be mainly rain, as 1000-850 mb thicknesses
remain above 1300 meters. However, with surface/boundary layer
temperatures close to freezing, cannot rule out spotty light
freezing rain or snow late tonight/early Thursday.

Rest of the forecast: Split flow is expected through the period,
with the forecast area firmly enternched in dry northern stream
zonal flow. A weak system passes well north of the region over the
weekend, with any precipitation staying to our north. The
remnants of the southern stream upper low kicks northeast toward
the Great Lakes during the middle of next week, and this could
bring a chance of precipitation. Overall, expect below normal
precipitation and seasonable temperatures through the week.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1124 AM CST Wed Nov 19 2025

High pressure will slide east this afternoon, allowing VFR
conditions with passing mid and high clouds to persist through
early evening. Winds will remain south to southwest at 5 to 10
kts.

Conditions are expected to deteriorate tonight as low-level
moisture returns ahead of an approaching cold front. MVFR/IFR
ceilings are forecast to overspread the region from 01z to 05z.
The poorest conditions are expected across north-central WI
(RHI/CWA/AUW), where ceilings will likely fall to LIFR/IFR levels
with visibilities dropping to MVFR/IFR in mist. Scattered light
rain or mixed precipitation is possible at RHI late tonight into
Thursday morning and kept the prob30 from 09Z-15Z.

Further east across the Fox Valley and lakeshore (GRB/ATW/MTW),
ceilings will lower to MVFR late tonight, but visibilities should
largely remain VFR. Improvement will be slow on Thursday morning,
with IFR/MVFR ceilings lingering through 15z-17z.

&&

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

&&

$$

UPDATE.........Kieckbusch
DISCUSSION.....Kieckbusch
AVIATION.......MPC