856
FXUS63 KGRB 030745
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
145 AM CST Tue Mar 3 2026

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Mainly dry through Thursday night.

- Widespread rain (80-100%) arrives Friday and lingers into
  Saturday. Thunderstorms possible late Friday afternoon and
  Friday night. Heavy rainfall possible.

- Mild, with highs in the 40s and 50s most days. Warm air flowing
  across lingering snowpack could lead to fog development at
  times.

- Warmer weather may lead to ice break-up on rivers, leading to
  ice jam flooding. Heavy rainfall Friday into Friday night could
  add to the flooding threat. Ice floes could also be a concern on
  Green Bay, especially late in the week.

&&

.DISCUSSION...
Issued at 144 AM CST Tue Mar 3 2026

Mainly Dry Weather Expected through Thursday night: A frontogenetic
band of light rain/virga has set up well to our south (over
northern IA) and is poised to stay south of the region. High
pressure persists through Wednesday, along with dry weather.
There is some concern for fog development tonight, due to partly
cloudy skies, light winds and low-level moisture from daytime
melting of snow. The fog should be most extensive where a depp
snowpack remains. The next system is expected to have a glancing
blow, with most if not all of the precipitation (rain) staying to
our south and east. Models are not in unaminous agreement on
this, with the Canadian ensembles still fairly aggressive with
rain over the southeast half of the area. Have kept 20-40% chances
for rain over the south/southeast counties, though I`m betting
these will be lowered as we get closer to the event.

Friday/Saturday System with Thunder/Heavy Rainfall Potential: The
main system of concern will impact the area Friday into Saturday
morning as a strong low pressure system moves from the central
Plains to the western Great Lakes. Rain is the main concern in the
mild air mass, with thunder possible as elevated instability
(MUCAPE of 300-500 j/kg) arrives in the SW CWA late Friday
afternoon and regionwide Friday night. Forcing will be provided by
strong WAA/ isentropic lift on the nose of a 35-40 knot low-level
jet, strong FGEN, and a warm front lifting into the southeast
part of the forecast area. This is followed by the passage of the
surface low Friday night into Saturday morning. PWATs surge to
1.0-1.3 inches across the southeast part of the forecast area,
leading to the potential for moderate to heavy rainfall,
especially where convection occurs. Could see minor flooding
impacts due to runoff from frozen ground, especially in
conjunction with any ice jam flooding that may be ongoing by that
time.

Mild Temperatures/Fog Potential...Much above normal temperatures
are anticipated through the week, with highs in the 40s and 50s
and lows in the 20s and 30s. Fog potential increases through the
week as rising dew points and melting snow add low-level
moisture. The greatest potential for fog development will be
the northwest half of the forecast area, especially north central
WI, where a deep snowpack remains.

Ice Jam/Ice Floe Potential...In addition to the previously-
mentioned potential for runoff flooding from heavy rainfall with
the Friday/Saturday system, there is a lesser threat of ice jam
flooding. The ice jam threat should gradually increase through
the week as warmer temperatures promote some break-up. The ice
jam threat will be reduced a bit due to low water levels, though
this could change if heavy rainfall occurs Friday/Friday night.
An increased threat of ice floes on Green Bay could also develop
later in the week, depending on how strong the Friday/Saturday
system is. Wind directions look favorable for a time from Friday
into Friday night, but there is some question about how strong the
winds will be.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1029 PM CST Mon Mar 2 2026

Cigs MVFR to VFR rest of tonight, with lowest cigs central to
north-central WI.

Uncertainty still remains on whether any light mixed precip will
enter the area late tonight. Latest trends seem to indicate area
of light precipitation over southern MN may diminish and/or stay
south of all the TAF sites. For now, will keep any precip mention
out of TAFs. Otherwise, MVFR to VFR clouds will gradually scatter
out on Tuesday afternoon. Winds will be light through the TAF period.

&&

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

&&

$$

DISCUSSION.....Kieckbusch
AVIATION.......JLA

NWS GRB Office Area Forecast Discussion