440
FXUS63 KGRB 071801
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
101 PM CDT Wed Oct 7 2026

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Hazardous conditions to small craft will continue on Lake
  Michigan through 7 PM this evening.

- Gusty west winds to 30 to 35 mph and low afternoon relative
  humidity will elevate fire weather concerns this afternoon
  across north-central and far northeast Wisconsin.

- Patchy frost will be possible over far northern Wisconsin early
  Friday morning with low temperatures in the mid 30.

- Unseasonably warm and windy conditions arrive Saturday and
  Sunday with inland high temperatures into the upper 70s to lower
  80s.

&&

.DISCUSSION...
Issued at 1259 PM CDT Wed Oct 7 2026

Gusty Winds and Low Humidity This Afternoon: With clear skies,
quickly warming surface temperatures this morning, and a compact
short-wave passing over the region the boundary layer has become
deeply mixed for this afternoon as evidenced by quickly increasing
wind gusts of 25-30kts being observed across northern WI early this
afternoon. Along with the winds the deep mixing has also resulted in
RHs falling to the low to middle 30s across northern WI with a few
locations likely dropping into the upper 20s this afternoon.
Combination of strong winds and low RHs is creating at least
moderate fire danger across parts of northern WI. Winds will quickly
diminish this evening after 00-02Z as the PBL stabilizes. RHs will
also quickly recover shortly after sunset as temperatures begin to
cool. The compact short-wave may also kick-off a few isolated
showers along the WI/UP border late this afternoon/evening, however,
with such a dry air mass in place QPF amounts are expected to be
minimal.

Thursday Night Patchy Frost Potential: Surface high pressure
building over the western Great Lakes Thursday night will create
favorable radiational cooling conditions beneath decoupling winds
and clear skies. Overnight minimum temperatures will drop into the
mid to upper 30s across north-central and far northeast Wisconsin,
including Rhinelander, Land O Lakes, and Crandon. NBM temperature
percentiles show a 40 to 70 percent probability of low temperatures
falling to 35 degrees or colder in sandy soil areas, supporting
patchy frost formation late Thursday night. Rapid diurnal warming
after sunrise Friday will quickly burn off any patchy frost with
daytime highs recovering into the upper 60s.

Weekend Unseasonable Warmth And Strong Winds: Strong warm advection
and return southerly flow will setup across Wisconsin Friday night
into the weekend as high pressure shifts to the East Coast. Inland
maximum temperatures Saturday and Sunday will likely reach the upper
70s to lower 80s, approaching daily record highs at some locations.
Tightening regional pressure gradients will produce strong southerly
wind gusts on Saturday, with NBM guidance showing a 35 to 55%
probability of gusts exceeding 35 mph area-wide. Medium to high
confidence exists in these unseasonably warm temperatures as NBM
25th to 75th percentile spreads remain narrow at 2 to 4 degrees F
across most of the area, however, there is some uncertainty with how
the remnant cloud shield from what is currently tropical storm
Isaias may impact daytime heating Saturday afternoon into Sunday
morning.

An advancing upper-level trough and associated surface cold front
will cross Wisconsin Sunday night into Monday, bringing returning
rain shower chances. Limited moisture transport ahead of the
boundary will restrict precipitation coverage, keeping 24-hour
rainfall probabilities between 40 and 60 percent across north-
central and northeast Wisconsin. NBM probabilistic guidance
indicates a 15-30 percent probability of 24-hour rainfall exceeding
0.50 inches, with expected liquid accumulations remaining around
0.25 inches. Post-frontal cold advection Monday night into Tuesday
will drop daytime highs back into the upper 50s and lower 60s for
early next week.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1120 AM CDT Wed Oct 7 2026

VFR conditions will continue through this TAF period with mid and
high clouds filtering over the region at times. The main aviation
impact will be the increasing west to northwest winds this
afternoon. The highest gusts of 25-30kts are expected at
RHI/AUW/CWA/GRB/ATW. Gusts up to 25 kts are expected at MTW. Gusts
will subside by 00-02z this evening. Clear and calm conditions are
expected overnight. West winds are expected to increase again after
sunrise Thursday morning.

&&

.MARINE...
Issued at 1259 PM CDT Wed Oct 7 2026

Gusty west winds of 25-30 kts are expected this afternoon along and
over the Bay. These increasing winds will create a short period of
conditions hazardous to small craft through early this evening
before winds quickly diminish after about 00-02Z.

Friday into this weekend a period of increasing and persistent
southerly winds will drive up waves and likely create another period
of hazardous boating conditions on Lake Michigan.

&&

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

&&

$$

DISCUSSION.....GK
AVIATION.......GK
MARINE.........GK

NWS GRB Office Area Forecast Discussion