NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 091151
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
651 AM CDT Thu Apr 9 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Aside from light rain across the the south half of the forecast
  area tonight, generally dry conditions are anticipated through
  Saturday.

- Periods of heavy rainfall and thunderstorms expected late this
  weekend through the middle of next week. 1.5 to 2" of rainfall
  expected, with locally higher amounts possible. Strong or severe
  thunderstorms possible Monday afternoon and evening.

- Minor flooding continues along the Wolf River, though runoff
  from melting snow in the Upper Peninsula paired with heavy rain
  may result in more widespread and significant flooding late this
  weekend into next week.

&&

.DISCUSSION...
Issued at 249 AM CDT Thu Apr 9 2026

The last remnants of the frontal band of rain was exiting east
central WI early this morning, followed by clearing skies over
most of the region. An upper low was moving through southern
Ontario, and CAA and subsidence on the south flank of this system
was generating gusty west winds over northern MN and northwest
WI.

West winds gusting to 25 to 30 mph can be expected today due to
subsidence and daytime mixing. Low clouds will move into the
northwest part of the forecast area, but the rest of the area
should see periods of sunshine. Highs will be in the 40s
northwest and over Door County, and 50s elsewhere.

Low pressure tracks south of the region tonight, but strong
mid-level FGEN brings light rain to mainly central and east
central WI. Some models show measurable precipitation as far north
as northern WI, but drier air should limit this to sprinkles or
flurries. Lows range from the middle to upper 20s northwest to the
middle to upper 30s southeast.

High pressure brings dry weather Friday into Saturday morning,
with a small chance of showers arriving in NC/C WI later Saturday
afternoon.

A prolonged period of active weather arrives Saturday night into
Sunday and continues through the middle of next week. Periodic
showers and thunderstorms, and potential for heavy rainfall, can
be expected through the period. The rain will be focused along a
frontal boundary that lifts north as a warm front late Saturday
night into Sunday, shifts back south and stalls across the area
Monday into Tuesday, and potentially lifts back to the north as a
strong low pressure system approaches Tuesday night into Wednesday.
This front will interact with a persistent flow of Gulf moisture
and marginal to moderate instability. Instability peaks across
the southwest half of the forecast area Monday afternoon and
evening, as CAPE increases to 1-2k j/kg. This moderate
instability, combined with the frontal boundary and deep layer
shear of 35-50 knots, could lead to a period of strong to severe
storms. Additional severe potential could occur on Wednesday,
depending on the track of the surface low. See the Hydrology
section for possible flooding impacts.

Milder temperatures are expected through the period, with highs
reaching into the 70s in parts of the area Sunday and Monday.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 645 AM CDT Thu Apr 9 2026

BKN stratocumulus clouds will impact mainly the western TAF sites
with ceilings between 2500-4000 ft AGL through late morning, then
ceilings should rise to VFR only. Clouds will increase regionwide
later this afternoon and evening, with frontogenetic forcing
aiding in light precipitation development during the later evening
and overnight hours. Most of the precipitation will fall as rain
across central and east central WI, but some sprinkles and
flurries may move through parts of northern WI for a few hours.

Gusty west winds will impact the area this morning, then gradually
diminish later today into tonight.
&&

.HYDROLOGY...
Issued at 249 AM CDT Thu Apr 9 2026

Minor flooding continues on the Wolf River early this morning.
A mainly dry period is anticipated through Saturday, with the
exception of light rain over parts of central and east central WI
tonight. Periods of heavy rain and thunderstorms arrive later in
the weekend and continue through the middle of next week.
During this upcoming period, probabilities for rainfall in excess
of 1 inch are 80-90%, with a 30-50% chance of amounts in excess
of 2 inches and a 5-15% chance of 3 inches or more. Current
forecasts call for 1.5 to 2 inches in most areas. Runoff from
this rainfall, combined with rapid snowmelt in the Upper
Peninsula and far northern WI, is expected to bring potential for
more widespread and significant flooding heading into the early
to middle part of next week. Right now, it appears the most
significant flooding impacts may occur on the Menominee River and
its tributaries.

&&

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

&&

$$

DISCUSSION.....Kieckbusch
AVIATION.......Kieckbusch
HYDROLOGY......Kieckbusch