281
FXUS63 KGRB 041943
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
143 PM CST Wed Mar 4 2026

.KEY MESSAGES...

- Periods of widespread rain and scattered thunderstorms Friday
  into early Saturday with low to medium (30 to 50%) chances
  for at least 1" of rain across central into east-central WI,
  although amounts will be variable with thunderstorm placement.
  This may lead to some ponding/standing water.

- Warmer weather may lead to ice break-up on rivers, leading to
  ice jam flooding. Ice floes could also be a concern,
  especially late in the week.

- Early spring warmth continues into early next week, with high
  temperatures likely exceeding 60 degrees for some areas
  Sunday/Monday.

- More precipitation chances (50-70%) return Tuesday/Wednesday
  although confidence in precipitation types and temperatures is
  lower.

&&

.DISCUSSION...
Issued at 143 PM CST Wed Mar 4 2026

Widespread rain/storms Friday into Saturday:

Relatively benign weather will continue through Thursday as
southwest flow develops aloft in response to a deepening trough over
the Four Corners Region. An embedded shortwave trough will may skirt
central into east-central Wisconsin with a low (20-40%) chance for
showers.

Warm advection will strengthen Thursday night into Friday as low
pressure develops to the west. The deeper moisture and higher rain
chances likely will hold off until Friday, but some patchy
drizzle/freezing drizzle could not be ruled out Thursday night,
depending on moisture depth.

Impressive moisture transport will occur ahead of the approaching
low pressure system on Friday aided by a 40+ kt low-level jet, with
NAEFS precipitable water values near the climatological max for this
time of year. Multiple rounds of showers and storms will occur in
association with the warm advection/moisture transport and frontal
passage Friday into early Saturday. There are still notable
differences in the strength of the upper wave and surface low
intensity/placement, which will impact the degree of destabilization
and warm sector placement. Steepening mid-level lapse rates
with at least modest elevated CAPE would support some small hail,
with any other convective hazards Friday evening dependent more
on boundary layer stability and surface low track.

With the convective nature of the rainfall and anomalous moisture in
place, rain amounts over an inch are plausible (30 to 50% chance for
central into east-central WI), with low (20-30%) chances for 1.5 to
2 inches of rain from central Wisconsin into the Fox Valley. This
may result in some river rises or ponding/standing water (localized
flooding), especially with substantial frost depth in place.
Some thawing of topsoil may help reduce some runoff, though.

Areas of fog may develop as warmer air overrides the cold
snowpack across northern Wisconsin.


Ice Jam/Ice Floe Potential:

There is a lesser threat of ice jam flooding, but the ice jam threat
should gradually increase through the week as warmer temperatures
promote some ice break-up. The ice jam threat will be reduced a bit
due to low water levels, though this could change if heavier
rainfall occurs. An increased threat of ice floes on Green Bay could
also develop later in the week, depending on how strong the
Friday/Friday night 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.


Warm into early Next Week:

After any lingering light rain/snow ends Saturday morning, a mild
Pacific airmass in zonal flow will prevail through the weekend.
Gusty southwest winds in warm advection and 925 mb temps
climbing into the 5-10C range Sunday afternoon per global
ensemble consensus suggest highs well into 50s or low 60s and
given the favorable mixing/thermal profiles, these temps could
trend a bit higher. Although low-level boundary placement will
impact temps early next week, an unseasonably warm airmass will
persist within the warm sector south of the front on Monday,
with some potential for record warmth. This environment with
gusty winds, warm and dry conditions would support increased
fire weather concerns, but antecedent rainfall and continued
snowmelt may limit this risk.


Unsettled Tuesday/Wednesday:

The next period of interest for impactful precipitation is
Tuesday and Wednesday next week. However, the evolution of a
closed low ejecting northeast from the southwest US with the
stronger westerlies to the north leads to lower predictability.
With deepening southwest flow aloft, global ensembles depict anomalous
(>90% percentile) precipitable water values returning northward
towards the Great Lakes.

However, there is substantial spread in the amplitude of the
longwave pattern within the ensemble envelope. In addition, a
pronounced east-west oriented baroclinic zone is forecast to be
draped across northern tier of states. Given the uncertainty in
the evolution of large scale flow pattern and low-level thermal
gradient position, the spread in temperatures is very large by
Tuesday with interquartile (25th-75th percentile) ranges from
the NBM from the upper 30s to low 70s across the area. Thus,
confidence in forecast details (temps, precip types and timing)
is low at this time.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1056 AM CST Wed Mar 4 2026

VFR conditions will continue this afternoon with light winds and
some high clouds. Winds will shift easterly overnight into
Thursday. Some patchy MVFR/IFR fog/stratus may develop (40-80%
chance) during the early morning, highest likelihood over
northern Wisconsin. In addition, soundings depict an increase in
low-level moisture overnight into Thursday from the south with
chances for MVFR ceilings increasing northward, but confidence
in timing/northward extent is lower. For now, limited MVFR to
KMTW and KATW.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
WI...None.
MARINE...None.

&&

$$

DISCUSSION...JM
AVIATION...JM

NWS GRB Office Area Forecast Discussion