781
FXUS63 KGRB 042305
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
605 PM CDT Sun Oct 4 2026

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- A Frost Advisory is in effect late tonight into early Monday
  morning for north-central and far northeast Wisconsin, where low
  temperatures will drop into the lower to middle 30s.

- Breezy southwest winds gusting 25 to 35 mph are expected Tuesday
  afternoon.

- Patchy frost will be possible again over far northern Wisconsin
  on Thursday night and Friday night with low temperatures in the
  mid 30s.

&&

.DISCUSSION...
Issued at 1133 AM CDT Sun Oct 4 2026

The latest RAP analysis and radar and satellite imagery show a
cold front moving over Lower Michigan this afternoon, while
surface high pressure builds in from the central Plains. Behind
the front, cold advection and Lake Superior moisture fluxes are
keeping strato-cumulus clouds scattered to broken over north-
central Wisconsin, though these clouds will mix out later today.
High pressure over the central Plains will migrate into the Great
Lakes tonight, while a Pacific cold front will approach the region
by Tuesday.

Frost And Near-Freezing Temperatures Tonight:
As high pressure moves into the region late tonight, clear skies
and precipitable water values at 50 to 60 percent of normal will
create decent radiational cooling conditions. Winds remain the
primary uncertainty, as statistical guidance suggests a light 3 to
4 knot breeze lingering overnight before decoupling toward
daybreak. This slight breeze may keep temperatures from dropping
as low as blended model guidance indicates, keeping confidence too
low for a Freeze Warning. A Frost Advisory continues for north-
central Wisconsin, with a 30 to 50 percent chance of temperatures
falling below 33 degrees across northern Forest and Florence
counties.

On Thursday and Friday nights, NBM percentiles also show a 30 to
50 percent probability of low temperatures falling into the
mid-30s across the Northwoods.

Strong Wind Gusts On Tuesday:
Southerly return flow strengthens on Tuesday as high pressure
slides east and a Pacific cold front approaches the Upper Midwest.
Warm advection will push daytime maximum temperatures into the
upper 60s to lower 70s across inland central and northern
Wisconsin. Tightening pressure gradients will produce gusty south-
southwest winds, with NBM guidance showing a 60 to 80 percent
probability of wind gusts exceeding 30 mph Tuesday afternoon.
Moisture transport remains limited, keeping precipitation
probabilities below 10 percent ahead of the frontal boundary.

Outlook for Hazardous Marine Conditions Through Tuesday Night:
Breezy northwest winds of 10 to 20 knots and waves of 2 to 4 feet
across northern Lake Michigan nearshore waters and Green Bay will
continue to gradually subside by late afternoon. Surface high
pressure centered over the region will then maintain quiet marine
conditions tonight through Monday, with winds under 15 knots
backing west to southwest Monday night and wave heights remaining
2 feet or less.

Hazardous marine conditions are expected to return Tuesday into
Tuesday night as an advancing Pacific cold front tighten the
regional pressure gradient. Southerly to south-southwesterly warm
advection winds will ramp up significantly Tuesday morning to 15
to 25 knots, with gusts reaching 25 to 30+ knots across nearshore
zones and potential for marginal gales over open Lake Michigan
waters. These strong onshore winds will build waves to 5 to 9
feet along the Lake Michigan shoreline and 3 to 5 feet on Green
Bay. Confidence is high that a Small Craft Advisory will be
required for all Green Bay and Lake Michigan nearshore zones
Tuesday afternoon through Tuesday night before winds shift
westerly and subside behind the cold front Wednesday morning.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 557 PM CDT Sun Oct 4 2026

VFR conditions will prevail through Monday afternoon. A deck of
clouds around 8,000 feet will move across northern WI this
evening before turn clear again overnight. Otherwise, northwest
winds should drop off quickly around sunset to 5 to 10 knots, then
continue around 5 knots overnight. Winds should back to the
south/southwest late Monday afternoon. The exception will be at
KMTW where winds should turn to the southeast around 20z. The
next chance of rain across northern WI will be Monday evening.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from 2 AM to 8 AM CDT Monday for WIZ005-010>013-
018>021-030-073-074.
&&

$$

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

NWS GRB Office Area Forecast Discussion