231
FXUS63 KGRB 221730
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1230 PM CDT Thu Oct 22 2026

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Areas of fog, locally dense, possible again late tonight into
  Friday morning.

- Mild into the weekend, with high temperatures inland of Lake
  Michigan warming into the mid 60s to low 70s.

- Light rain chances (20 to 40%) return Saturday evening,
  continuing at times through Monday. Rain chances linger through
  much of next week.

- Cooler next week, with highs mainly in the 50s.

&&

.DISCUSSION...
Issued at 1215 PM CDT Thu Oct 22 2026

Fog... Onshore breeze off the Bay has kept patchy fog around
portions of east-central into far northeast Wisconsin through
early this afternoon, though dense fog has lifted. Signal then
once again exists for fog development late tonight into Friday
morning due to continued onshore flow and light winds aloft,
though remain uncertain if this will materialize as fog or low
stratus. CAMs remain divided in this regard, though current
thinking is that there may be just enough mixing to keep low
stratus deck elevated. Radiational cooling late tonight is also
not looking as good as it did this morning. For the above reasons,
have opted out of issuing an advisory, though trends will have to
be monitored into this evening.

Rain chances... Light rain chances increase Saturday evening as
low pressure ejects into northern Canada and trailing cold front
progresses over the upper Midwest. Moisture return along the slow-
moving boundary will nudge PWATs into the 1 to 1.25" range
Saturday into Sunday (~90th percentile), which should work in
tandem with upper jet energy to keep periodic rain chances in the
forecast through the weekend. Blended PoPs continue to trend in
the 20 to 40% range, though suspect these will have to be
increased within the next day or two with front in the vicinity.
NBM probabilities show a 20 to 40% chance for receiving 0.25" of
QPF through Monday. Beyond Monday, similar pattern of on/off rain
chances exists as upper flow flattens out, opening the door for
several shortwave passages within the 500 mb wave train. However,
overall rainfall amounts should be held to a minimum with high
pressure in the area and lack of forcing mechanisms at the
surface.

Temperatures... Arctic high sliding south in the wake of the front
Monday into Tuesday will bring about a spell of below average
temperatures during the middle of next week, with highs only
getting into the mid 40s to mid 50s. However, cooler temperatures
will be short-lived as return flow sets up on Wednesday, warming
highs back up into the 50s and 60s. Monday night lows will fall
into the low to mid 30s across the north, though little to impacts
are expected since the growing season has come to an end.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1215 PM CDT Thu Oct 22 2026

Onshore fog off of the southern Bay and along the lakeshore has
been slow to lift early this afternoon, with locally reduced vsbys
persisting over portions of east-central Wisconsin. Have thus
included a TEMPO group for LIFR cigs at GRB and MTW where fog
continues to lift into a low stratus deck. Lower cigs should
continue to improve within the next several hours, eventually
becoming VFR at all terminals later this afternoon. Another round
of low stratus and/or fog is then possible late tonight into
Friday morning. Otherwise, winds will be mainly out of the
east/southeast at under 10 knots throughout the TAF period.

&&

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

&&

$$

DISCUSSION.....Goodin
AVIATION.......Goodin

NWS GRB Office Area Forecast Discussion