835
FXUS63 KGRB 031802
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1202 PM CST Tue Mar 3 2026

Forecast discussion for routine afternoon 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, especially south and east. Heavy rainfall and
  strong storms 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 breakup 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,
  especially late in the week.

&&

.DISCUSSION...
Issued at 1202 PM CST Tue Mar 3 2026

Mainly Dry Weather Expected through Thursday night:

High pressure will persist across the region 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 deep 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 on Thursday. Models are not in unanimous agreement on this,
with the Canadian ensembles still fairly aggressive with rain over
the southeast half of the area. Have kept 20-50% chances for rain
over the south/southeast counties per the NBM; however, it
wouldn`t be shocking if these are 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 500-1000 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 almost the entire 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.

Severe Weather Potential:

The severe weather potential late Friday afternoon into Friday
night has increased some, as evidenced by the SPC Day 4 outlook
surging the 15% severe weather potential into southern Wisconsin
and at our doorstep. Instability has increased this run, with
MUCAPEs of 500-1000 J/kg. Although bulk shear values are 60 knots,
effective shear is a more modest 20 knots. Given the elevated
nature of these storms the bulk shear is probably not a great
indicator of the severe weather potential given the amount of
shear below the steep inversion around 900 mb. At this point the
severe weather potential is still low; however, it has increased
from the previous forecast and the trend is further north. That
being said, cannot rule out some strong storms during this period
with gusty winds being the main threat given the very elevated
hail growth zone and fairly skinny CAPE profiles.

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 Wisconsin, 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 18Z TAF Issuance
Issued at 1126 AM CST Tue Mar 3 2026

MVFR CIGs across central Wisconsin should give way to VFR as drier
air breaks up the clouds across the region later this afternoon.
This breaking up the clouds and drier air are evident on satellite
imagery and progressing eastward. Further north, MVFR/VFR CIGs
will remain with some breaks in the clouds at times.

Partly cloudy skies, light winds and moisture from melting snow
will combine to produce areas of fog, locally dense, late tonight.
The fog will be most extensive over the northwest half of the
forecast area, where a deep snow pack remains. Any fog will then
dissipate Wednesday morning.

&&

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

&&

$$

DISCUSSION.....Kurimski
AVIATION.......Kurimski

NWS GRB Office Area Forecast Discussion