572
FXUS63 KGRB 121923
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
223 PM CDT Mon Oct 12 2026

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- There is a 30 to 90% percent chance for light rain across the
  region this evening and early overnight, highest chances north.
  A couple rumbles of thunder will also be possible at times.

- Chances for more widespread soaking precip arrive late this
  week, though there is still much uncertainty. Much cooler
  temperatures next weekend.

&&

.DISCUSSION...
Issued at 223 PM CDT Mon Oct 12 2026

Precipitation tonight...
A surface low will track into the area this evening, accompanied
by a mid-level shortwave. The highest rain chances (70-90%)
accompanying the low will be on the northern edge of the warm air
this afternoon across northern Wisconsin, mainly north of a line
from Merrill to Oconto. Probabilistic guidance keeps a corridor of
40-60% chance of exceeding a half an inch of rainfall for the
northern areas. Precipitation potential will quickly taper off
south of this line, with around 20-40% chance across most of the
rest of the area. Still, would expect some short-lived showers to
produce some quick accumulations for central to east- central with
more measurable precipitation for northern Wisconsin. Some meager
upper instability accompanying showers could prove sufficient to
produce an occasional rumble of thunder (10-20% chance), but
expect widespread thunderstorms to be unlikely.

Precipitation Towards the End of the Week... A larger phasing
system is expected towards the end of the week as southern and
northern streams merge. Phasing systems generally have much
uncertainty in terms of timing but some general agreement has come
into alignment with the most recent forecast cycles. Rain will
start sometime in the late morning to afternoon hours and cross
the region into the overnight hours. How long the system remains
around into Friday remains uncertain and will depend largely on
whether the phasing occurs overhead or to our east. On the shorter
end, dry conditions could be back by Friday morning and on the
longer end some wrap around moisture could keep a few showers
around into Friday afternoon. Both solutions do still suggest
bringing enough cold air in on the backside of the system to
produce the first snowflakes across far north- central Wisconsin
near the Upper Peninsula border, but accumulations will generally
be brief and light. This system will also bring another period of
windy conditions for Friday.

Temperatures...
The near-record temperatures today will be the warmest
temperatures in the forecast, with high temperatures seeing a
downward trend through the end of the week. Friday is expected to
be the coldest day, with highs in the upper 40s in the northwoods
to middle 50s in the warmest areas. A small warmup trend is then
in store for the region over the weekend into next week.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1230 PM CDT Mon Oct 12 2026

VFR conditions will persist through the afternoon as high clouds
cross the region. Cloud coverage then increases ahead of a surface
low pressure system that will bring showers into portions of
northern and central Wisconsin. Confidence on the southern extent
of showers remains low, so maintained a PROB30 group for TAF
terminals across central to east-central Wisconsin. Confidence is
higher for the north so included the TEMPO for the rain passage
this evening.

Lower clouds will wrap in behind the low pressure system in the
mid to late morning tomorrow, so would expect ceilings to drop to
MVFR and eventually IFR during the mid-morning hours of Tuesday.
Some improvement will be possible towards the end of the TAF
period as clouds begin to scatter out again.

&&

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

&&

$$

DISCUSSION.....Uhlmann
AVIATION.......Uhlmann

NWS GRB Office Area Forecast Discussion