403
FXUS63 KGRB 160630
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
130 AM CDT Fri Oct 16 2026

New Information added to update section

.UPDATE...
Issued at 121 AM CDT Fri Oct 16 2026

Per coordination with surrounding offices, upgraded the Freeze
Watch to a Freeze Warning for portions of central, east-central
and portions of northeast WI. Winds are expected to drop off late
tonight across the Door peninsula, thus have added a Frost
Advisory where areas of frost will be possible over interior and
southern sections of the county.

&&

.KEY MESSAGES...

- Widespread rain continues tonight, becoming scattered into
  Friday morning. Most locations should see an additional 0.25 to
  0.5" of rainfall.

- Northwest winds increase on Friday, with gusts between 30 and 40
  mph expected. Locally higher gusts to 45 mph will be possible
  along the lakeshore counties. Gale force gusts are expected
  across marine zones.

- A Freeze Warning is in effect late tonight into early Saturday
  morning for much of central, east-central and portions of
  northeast Wisconsin.

- A Frost Advisory has been posted for late tonight into early
  Saturday morning for Door County. Areas of frost are anticipated
  over interior and southern sections of the county.

&&

.DISCUSSION...
Issued at 900 PM CDT Thu Oct 15 2026

Rain chances through Friday... Radar and surface obs show
widespread stratiform rain ongoing late this evening as cold front
infringes on northwest Wisconsin and phased upper trough
approaches the Great Lakes. Expect rain to become more scattered
in coverage overnight into Friday morning with the loss of
moisture advection and upper jet support, though most locations
should still pick up an addition 0.25 to 0.5" of QPF.
Probabilities for receiving 0.5" of rain through tonight sit at
around 30 to 60%, highest over far northeast Wisconsin where
modest mid-level FGEN resides in proximity to the surface low.
Rain then tapers off from west to east late Friday morning, though
wrap around moisture may keep showers or drizzle around over
east-central Wisconsin through the afternoon.

Winds... Gradient winds ramp up Friday morning as a surge of CAA
accompanies northwesterly wind shift and building high pressure
over the Plains. Deep daytime mixing will tap into 40 to 45 knot
winds at 850 mb Friday afternoon, resulting in a high confidence
(60 to 90%) setup for widespread surface gusts between 30 and 40
mph. Only caveat will be Door County, where locally higher gusts
will be bumping up against advisory criteria. HREF currently
shows a 20 to 40% chance for gusts exceeding 44 mph over northern
Door, with sustained winds also coming within a mph or two of
criteria. Current thinking would be to hold off on an advisory for
the time being due to low confidence, though CAM trends will have
to be monitored on subsequent shifts.

Temperatures... Intrusion of arctic high paired with stout
northwesterly flow will result in a brief spell of well below
normal temperatures Friday and Friday night. Highs will struggle
to meet 50 degrees for many locations, with lows then plummeting
into the mid 20s to low 30s. Setup still looking favorable (50 to
70%) for a hard freeze Friday night, so have retained the Freeze
Watch. A rapid pattern shift to more seasonable temperatures then
occurs over the weekend as return flow sets up and upper flow de-
amplifies. As such, highs are progged to read mainly in the mid to
upper 60s through at least mid-week, with several shots at seeing
70 degrees.

Extended... High pressure looks to be the main driver of the
synoptic pattern through at least the middle of next week, with
no organized systems on the horizon. More active pattern then looks
to set up toward the end of next week as upper flow re-amplifies,
though details are few this far out.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1241 AM CDT Fri Oct 16 2026

Light rain or drizzle will continue overnight and then on
Friday morning. IFR CIGS will improve into the MVFR category,
then VFR by early to mid afternoon. North/northwest winds
of 15 to 25 knots with gusts of 30-40 kts expected late
morning through mid afternoon before winds ease during the
late afternoon and early evening hours.

&&

.MARINE...
Issued at 900 PM CDT Thu Oct 15 2026

Gale Warning remains on track for the Bay and Lake as northerly
winds ramp up following cold FROPA later this evening. HREF
probabilistic guidance is currently showing a 65 to 95% signal for
10-meter wind gusts exceeding 39 mph, which should translate
pretty well to gale force gusts over our marine zones. Waves will
build 4 to 7 ft on the Bay and 6 to 10 ft on the Lake during this
time. Have opted to throw out a wind down Small Craft Advisory
along the Lake Michigan nearshore waters on this shift, as waves
remain elevated through around 08Z Saturday as winds shift to more
westerly.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Freeze Warning from 1 AM to 9 AM CDT Saturday for WIZ020-030-031-
035>040-045-048>050-073-074.

Frost Advisory from 3 AM to 9 AM CDT Saturday for WIZ022.
&&

$$

UPDATE.........Eckberg
DISCUSSION.....Goodin
AVIATION.......Eckberg
MARINE.........Goodin

NWS GRB Office Area Forecast Discussion