NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 200623
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
123 AM CDT Fri Mar 20 2026

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Areas of dense fog possible this morning across central to
  north- central Wisconsin.

- Next chance of a wintry mix and snow (20-40%) Saturday night
  into Sunday, especially over northern Wisconsin.

- Temperatures surging above normal today and Saturday, with the
  warmth peaking Saturday (mid to upper 50s).

- Snowmelt and increased flows and rising levels on rivers and
  streams are expected. Several rivers may reach bankfull or even
  minor flood stage beginning this weekend.

&&

.DISCUSSION...
Issued at 122 AM CDT Fri Mar 20 2026

A clipper system will bring some light rain to far northeast
Wisconsin early this morning, with snow and freezing rain possible
near the Michigan border. In addition, some patchy fog will be
possible later this morning with abundant low level moisture over
a cold snowpack. The worst visibility restrictions are expected
across central and north-central Wisconsin, where locally dense
fog is possible.

Dry weather is then expected the rest of today as temperatures
continue their climb across the western Great Lakes region. Highs
today are expected to range from the lower to middle 40s across
the Fox Valley with around 50 degrees north and west of the Fox
Valley where NBM probabilities of exceeding 50 degrees are
50-80%.

Saturday will likely be the warmest day of the week as an
approaching low pressure system from the Plains brings a surge of
warm air over the western Great Lakes region. NBM probabilities of
exceeding 60 degrees have increased to 40-80% southwest of a line
from Mosinee to Oshkosh. The rest of the area will likely see
temperatures in the 40s across far northeast Wisconsin, with 50s
in between these areas. Precipitation on Saturday will mainly be
limited to far northern Wisconsin near the Michigan border
associated with isentropic lift near the warm front.

The cold side of this low pressure system will track through the
area Saturday night, bringing colder temperatures and a rain/snow
mix as a cold front sinks south through Sunday. The chance of
precipitation is 20-40%, with most of the precipitation occurring
on Saturday night. NBM 24 hour probabilities for accumulating
snow have trended down precipitously and are currently de minimis,
clocking in at 10% or less across far north-central and northeast
Wisconsin ending Sunday evening.

High pressure will then provide dry weather to the area early
next week. Temperatures will start off at or slightly below
normal, but quickly rebound to slightly above normal by the middle
of next week. A clipper system will also be moving through the
middle of next week. This system has a lot of uncertainty
surrounding it, as evidenced by the large spread in probabilistic
data. Current 24 hour NBM probabilities for an inch or more of
snow during the middle part of next week are 20-30% across north-
central Wisconsin.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1040 PM CDT Thu Mar 19 2026

A light wintry mix is possible from KIMT to KMNM to K2P2
through 08z. Otherwise, main concern for tonight will be the
potential for confidence. Confidence is high that there will
be areas of fog around, but confidence is low if the fog would
become dense at times. Any lingering fog should burn off by
15-16z. Southerly winds are expected to veer to the west and then
northwest overnight into Friday morning. A lake breeze boundary
is anticipated at KGRB/KATW/KMTW late Friday afternoon. Areas of
fog are expected again Friday night into Saturday morning, and
could be dense at times.

&&

.HYDROLOGY...
Issued at 122 AM CDT Fri Mar 20 2026

As temperatures warm across the region, the snowmelt will result
in increasing fast flows and rising river levels. Some rivers
could reach bankfull or even minor flood stage. The lack of a
rapid, significant warmup points to a more gradual rise in area
rivers as opposed to widespread rapid rise flooding. That being
said, the flooding situation will be monitored closely given how
much water is locked up in the current snowpack across the region.
Latest Snow Water Equivalent (SWE) here at our office is now 2.88
inches with a snow depth of 14 inches. This matches the current
NOHRSC snow depth and SWE analysis pretty well. Modeled snowpack
temperature from the NOHRSC site points to ripening of snowpack
(really starting the melting/runoff process) over central WI as
early as today, with more widespread ripening of snowpack up over
the area on Saturday.

&&

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

&&

$$

DISCUSSION.....Kurimski
AVIATION.......Eckberg
HYDROLOGY......Kurimski