213
FXUS63 KGRB 210555
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1255 AM CDT Sat Mar 21 2026

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

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

- Areas of fog and low clouds expected this morning. A 20 percent
  chance of rain or freezing rain near the Upper Michigan border.

- Rain (30-50% chance) tonight into Sunday morning. Rain may
  briefly mix with snow or sleet before ending, but little or no
  accumulation is expected.

- Well above normal temperatures expected today, especially in
  central Wisconsin, where highs could reach well into the 60s and
  possibly 70 (20-40% chance). Mild readings into the 50s are
  also anticipated next Tuesday and Thursday.

- A wintry mix of precipitation possible during the middle of
  next week, especially Wednesday into Thursday.

&&

.DISCUSSION...
Issued at 1255 AM CDT Sat Mar 21 2026

Some patchy fog and stratus will impact the region this morning
with light winds and low-level moisture from melting snow. Once
the fog dissipates, there will be a small (10-30%) chance for
rain or freezing rain this morning in response to isentropic lift
in a moisture starved air mass.

Today will likely be the warmest day of the week as an
approaching low pressure system from the Northern Plains brings a
warm front and associated surge of very mild air into the forecast
area. This warmth will primarily be felt in central Wisconsin,
where there is a 60-80% chance of highs greater than 65 degrees
and a 20-40% chance of highs hitting 70 degrees across the far
southwest corner of the region. Farther north and east, a
combination of low clouds (north of the warm front) and SE-S winds
off Lake Michigan will keep readings in the 40s and 50s.

As the low shifts east, a cold front will sweep through the
forecast area during the late afternoon/evening. Models show
strong mid-level FGEN forcing with this system, which should
bring a band of light rain through the area tonight into early
Sunday. This band should sag southeast with time, with the lagging
influx of colder air only leading to a brief period of mixed
precipitation (mainly sleet/snow) on the northwest periphery of
the precipitation band. Therefore, not expecting much (if any)
snow accumulation. Most of the precipitation should be gone by
Sunday afternoon.

High pressure will then provide mainly dry weather and more
seasonable temperatures from Sunday afternoon through Monday
night. Another clipper system will move through during the middle
of next week. This system looks fairly similar to this weekend`s
system, with potential for a light mix of rain/snow, especially
Wednesday into Thursday. Mild days occur ahead of the clipper on
Tuesday, and within a dry slot on Thursday, with potential for
50s both days.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 903 PM CDT Fri Mar 20 2026

VFR conditions prevailed across the forecast area this evening.
Mostly clear skies, decoupling winds, and ample low-level
moisture from melting snow will then result in a window for fog
development late this evening and overnight, potentially dropping
vsbys into IFR or LIFR territory. However, opted not to include
any TEMPO groups, as it is still uncertain whether or not this
will materialize as fog or low stratus. Slight chances for rain or
freezing rain then arrive from the north toward the end of the
TAF period, though this should remain north of RHI.

Winds will gradually veer to south/southwesterly throughout the
day on Saturday, picking up slightly Saturday afternoon. Gusts
between 15 and 20 knots will be possible. LLWs may become a
concern late Saturday morning and afternoon as 850 mb winds ramp
up.

&&

.HYDROLOGY...
Issued at 1255 AM CDT Sat Mar 21 2026

As temperatures warm across the region, the snowmelt will result
in increasing flows and rising river levels. Some rivers could
reach bankfull or even minor flood stage starting this weekend.
The lack of a prolonged 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. Modeled snowpack temperature
from the NOHRSC site points to widespread ripening of the
snowpack (and higher susceptibility of melting/runoff) over the
area today.

&&

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

&&

$$

DISCUSSION.....Kurimski
AVIATION.......Goodin
HYDROLOGY......Kurimski

NWS GRB Office Area Forecast Discussion