418
FXUS63 KGRB 061619
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1119 AM CDT Mon Apr 6 2026

Updated aviation portion for 18Z TAF issuance

.KEY MESSAGES...

- Scattered snow showers today. Some of the snow showers may be
  heavy and cause brief visibility reductions/minor travel
  impacts.

- Next potential for precipitation Tuesday night through Wednesday
  night. Probabilities for at least 0.50 inch of liquid
  precipitation between 20-50%, and for at least 0.5 inch of snow
  between 20-40% mainly north and west of the Fox Valley.

- Potential is increasing for additional heavier precipitation
  late this weekend into early next week. Probabilities for at
  least 1 inch of rain between 50-70%.

- Minor flooding will continue along some rivers this week due to
  recent rainfall. Additional precipitation over the next week may
  exacerbate flooding in some areas.

&&

.DISCUSSION...
Issued at 356 AM CDT Mon Apr 6 2026

Scattered Snow Showers Today...This morning`s surface
observations and satellite and radar imagery indicated flurries or
sprinkles were falling from a low stratus cloud deck at times,
which coincided with a 500mb vort max over the area. This 500mb
vort max will exit the region later this morning, but another one
is progged to move into the area by midday in addition to a
surface boundary beginning to drop south over the area. Paired
with steep low-level lapse rates and some surface instability,
CAMs remain on track with diurnally driven scattered snow showers
developing over the area. Inverted-V forecast soundings would also
indicate these bursts of snow would produce gusty winds of 25 to
30 mph, with slightly higher gusts to 35 mph over the Door
Peninsula. Given these favorable parameters, the snow showers may
become briefly heavy with visibility reduced to under a mile
through the early evening, which may impact the evening commute.
Warmer roads may limit travel impacts, but as air temperatures
fall below freezing into this evening some cooling of the roads
should still occur. Some slippery spots on untreated roads,
bridges, overpasses, and sidewalks may still occur during the
evening. Any of the snow showers will come to an end a few hours
after sunset with the loss of daytime heating and as high pressure
moves into the area. Snow accumulations will remain on the lighter
side with a dusting to a couple tenths of an inch in most spots,
but upwards of an inch in Vilas County due to this morning`s
lingering lake-effect snow showers.

Colder air will trail behind this boundary tonight causing
temperatures to fall into the single digits in far north-central
WI and the teens to low 20s farther south.

Midweek Precipitation...Low-level southwest flow ahead of a low
pressure system/cold front looks to generate some WAA driven
precip over the area Tuesday night into Wednesday. Forecast
soundings indicate there may be a brief period of a wintry mix at
the onset of this precipitation before surface temps/boundary
layer temps warm above freezing. By Wednesday morning, locations
north and west of the Fox Valley could see some snowfall as probs
for at least 0.5 inch of snow are between 20-40% in these areas.
This will be follows by pre-frontal rain occurring between
Wednesday afternoon and Thursday morning. Probabilities for at
least 0.50 inch of liquid precipitation are between 20-50%, with
lower chances in far north-central WI.

Rest of the forecast...High pressure will be dominant over much of
the area on Friday, but there are indications of the southern
portions of the forecast area seeing some precip from a system
tracking south of the area. An unsettled pattern looks to set up
late this weekend into early next week, causing the potential for
heavier precipitation to increase, which long-range ensembles
support with probabilities for at least 1 inch of rain between
50-70% area-wide. Given the saturated conditions and elevated
river levels, this will be a period to watch.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1119 AM CDT Mon Apr 6 2026

Scattered snow showers will continue into early this evening.
Conditions will generally be MVFR; however there will be breaks in
the clouds at times with VFR conditions as well as IFR/LIFR
conditions within the heavier snow showers. Flying conditions will
improve to VFR as the snow showers come to an end later this
evening.

Northwest winds will prevail through the TAF period. Gusty winds
are expected through this evening, peaking early this afternoon,
with gusts of 20 to 25 kts. However, within the heavier snow
showers, winds may gust up to 35 kts. Winds will subside below 10
kts late this evening.

&&

.HYDROLOGY...
Issued at 356 AM CDT Mon Apr 6 2026

Many area rivers across central and eastern WI remain at/near
bankfull or in minor flood stage this morning due to runoff from
recent rounds of rainfall and melting snow/sleet. The Yellow,
Peshtigo, Oconto, Embarrass, and other rivers/streams in eastern
WI will level off and slowly fall the next couple of days. The
Wolf, especially near Shiocton, will continue to slowly rise into
mid-week. No rivers are forecast to reach moderate flood stage. No
river flooding is expected across north-central WI, where less
rainfall fell and some snow is still on the ground.

The isolated rain/snow showers today will not have any impact on
the flooding. The Tuesday night and Wednesday system will bring a
little more substantial rain, but current probabilities of over
0.5" of rain (or liquid equivalent) are only between 30-50%
(highest in central WI). We will have had at least a couple days
to dry out, which will allow more water to push through the
rivers. So while the additional rainfall could slow the fall of
some river levels slightly and possibly create some minor low-
land flooding, no additional significant flooding is anticipated.
Will need to keep an eye on next weekend and/or early next week
as the flow turns southwesterly again, ushering in PWATs over an
inch and possible rounds of heavier precip, which could bring a
more substantial flooding threat.

&&

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

&&

$$

DISCUSSION.....Kruk
AVIATION.......Kurimski
HYDROLOGY......Bersch

NWS GRB Office Area Forecast Discussion