870
FXUS63 KGRB 141704
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1204 PM CDT Wed Oct 14 2026

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Widespread rain will develop Thursday afternoon and continue
  through Friday. NBM probabilistic guidance indicates a 60 to 90
  percent chance of 24-hour rainfall accumulations exceeding 0.50
  inches across the region.

- Northwest winds increase on Friday, with gusts between 35 and 45
  mph possible. Gale force gusts expected across marine zones.

- A widespread frost/freeze event is expected Friday night into
  early Saturday morning.

- A warming trend and breezy southwest winds will bring daytime
  high temperatures back into the 60s late this weekend with
  minimal rain chances through midweek.

&&

.DISCUSSION...
Issued at 1204 PM CDT Wed Oct 14 2026

The current surface analysis shows high pressure centered over
the northern Plains, maintaining a cool northwest flow regime
across the western Great Lakes. Widespread low stratus continues
across northern Wisconsin with moisture trapped beneath a
subsidence inversion centered between 800mb and 750mb. Upstream,
an amplifying northern stream shortwave trough digging out of
western Canada will induce cyclogenesis over the central Plains
before tracking into the Upper Midwest. This surface low will
bring widespread rainfall and strong cold advection to Wisconsin
on Thursday and Friday.

Widespread Rain Thursday Into Thursday Night: An amplifying
shortwave and developing surface cyclone tracking northeast across
the Great Lakes will spread rain into central Wisconsin around
midday Thursday before reaching northeast Wisconsin in the
afternoon. Robust dynamic forcing and moderate mid-level
frontogenesis interacting with a moisture plume featuring
precipitable water values 180 percent of normal will yield
widespread rainfall. NBM probabilistic guidance indicates a 60 to
90 percent chance of 24-hour liquid accumulations exceeding 0.50
inches, with expected storm total rainfall between 0.50 and 1.00
inch. Rain will diminish in intensity late Thursday night as the
system center exits to the northeast, but scattered showers are
expected to continue through much of Friday within strong cyclonic
flow.

Strong Friday Wind Gusts And Marine Gales: Strong cold air
advection surges across Wisconsin Friday morning on the backside
of the departing cyclone, dropping 850mb temperatures over western
Lake Superior to -4 degrees C. Deep cyclonic flow combined with
steep boundary layer lapse rates will drive strong northwest wind
gusts. NBM guidance shows a 40 to 70 percent chance of wind gusts
exceeding 40 mph inland, while gale-force wind gusts and wave
heights of 6 to 10 feet create hazardous marine conditions across
Green Bay and Lake Michigan. Winds will begin to subside late
Friday afternoon as the pressure gradient relaxes.

Widespread Friday Night Hard Freeze And Frost: Canadian surface
high pressure quickly building into Wisconsin Friday night will
bring in very cold air beneath clearing skies and diminishing
winds. Overnight minimum temperatures will plummet into the
mid-20s to lower 30s across north-central and central Wisconsin,
with mid-30s near the Lake Michigan shore. NBM probabilistic
guidance displays high confidence in a widespread hard freeze,
showing a greater than 90 percent chance of temperatures below 33
degrees west of the Fox Valley and a 60 to 90 percent chance
eastward. Rapid solar heating Saturday morning will quickly burn
off widespread frost, warming daytime temperatures into the mid to
upper 50s.

Breezy Weekend Warming Trend And Minimal Rain: Return southerly
flow and warm advection strengthen Saturday afternoon into Sunday
as surface high pressure shifts to the East Coast. Daytime high
temperatures will rebound into the 60s over the weekend and reach
the upper 60s by Tuesday under mostly sunny skies. Tightening
regional pressure gradients will produce breezy southwest winds,
with NBM guidance indicating a 50 to 70 percent probability of
gusts reaching 30 to 35 mph on Saturday and Sunday. High
confidence exists in minimal precipitation coverage with NBM
24-hour rainfall probabilities remaining under 10 percent through
midweek.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1204 PM CDT Wed Oct 14 2026

A mix of MVFR and low end VFR ceilings prevail across the region
late this morning. Ceilings should continue to rise through the
afternoon with help from daytime heating, but a profound clearing
trend is not expected due to a stout inversion above 800mb.
Ceilings are forecast to fall to IFR/MVFR again after 06Z Friday.
As low pressure tracks towards the region, light rain will be
approaching the central and east-central WI TAF sites between
16-18Z Thursday.

&&

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

&&

$$

DISCUSSION.....MPC
AVIATION.......MPC

NWS GRB Office Area Forecast Discussion