Green Bay, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

379
FXUS63 KGRB 150417
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1117 PM CDT Tue Oct 14 2025

Updated aviation portion for 06Z TAF issuance

.KEY MESSAGES...

- Showers will increase late this afternoon into tonight, but
  amounts will be generally light with 20 to 40% chances for at
  least 1/4 inch.

- Intermittent showers Thursday into the weekend with a small
  (10-30%) chance for non-severe thunderstorms Thursday night
  into Friday night.

- Seasonable temperatures will prevail through the middle of the
  week with well above average temperatures in the 60s to low
  70s for Friday and Saturday.

&&

.DISCUSSION...
Issued at 230 PM CDT Tue Oct 14 2025

Tonight-Wednesday: Showers Tonight

Despite the influence of Canadian high pressure across the Upper
Great Lakes region, radar mosaics showed returns extending from
Minnesota/Iowa into western/central Wisconsin in association
with mid-level warm advection/frontogenesis. 12Z GRB/MPX
soundings showed substantial dry air below 700 mb with more
moisture present in the mid-levels at MPX. Despite the stubborn
dry air in place, some light rain has been reported within the
higher returns nosing eastward from central Wisconsin this
afternoon. The higher chances for more widespread showers
(60-90% chance) come late today/tonight when mid-level
frontogenesis is strongest. However, rain amounts will generally
be modest with only low (20-40%) chances of exceeding 1/4 inch,
mainly across central Wisconsin per the HREF. Much of the day
on Wednesday looks dry and seasonable as the shortwave trough
pushes east and high pressure is the dominant influence.

Thursday-Sunday: Warmer, unsettled at times

Broad mid-level ridging and return southerly flow will start to set
up on Thursday ahead of a deep trough and associated surface low
that will lift northeast from the Rockies into the northern plains
late this week, eventually dragging a cold front through over
the weekend.

Warm advection will increase ahead of a warm front Thursday into
Thursday night with medium (40-60%) chances for showers. Although
any instability looks quite weak, an isolated thunderstorm (<20%
chance) could not be ruled out, especially Thursday night as a
strong low-level jet develops, with the NAEFS showing
precipitable water values exceeding the 99th percentile of
seasonal climo.

Ahead of the front on Friday, unseasonably mild high temperatures
are likely, with NBM interquartile ranges (25-75th percentiles)
generally from the mid 60s to mid 70s. The front should slide
through Friday night into Saturday morning with additional
showers. Instability again should be quite modest, but a rumble
of thunder cannot be ruled out. Although details of its
evolution vary somewhat, occasional showers may linger through
the weekend (20-40% chance) beneath the upper level trough.
Highs on Saturday will depend somewhat on frontal timing, but
Sunday will trend cooler/seasonable.

Monday-Tuesday: Active pattern continues

The active weather pattern looks to persist into early next week
with another Pacific trough set to eject east from the Rockies.
Global ensembles depict large spread with the timing and
amplification of the upstream trough and downstream ridging across
the central US. Accordingly, spread in temps increases significantly
by Tuesday with only lower end rain chances (20-30%) given
these differences.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1116 PM CDT Tue Oct 14 2025

Showers will diminish from north to south overnight across the
region. CIGs overnight into Wednesday could dip into MVFR with the
highest chances (70-90%) across central Wisconsin with smaller
chances across the Fox Valley (30-50%) and even lower farther
north and east. There is a chance for IFR CIGs (10-30%); however,
the chance is too low to put in the TAF sites. Skies will then
become VFR through the day on Wednesday. Under the influence of
surface high pressure, winds will generally remain near or under
10 kts, perhaps a bit gustier from the NE along Lake Michigan at
times.

&&

.MARINE...
Issued at 1228 PM CDT Tue Oct 14 2025

Winds will increase out of the southeast on Thursday as low
pressure develops west across the plains. A cold front will move
through Friday night into Saturday with winds becoming westerly
in its wake. Small craft conditions (gusty winds and increasing
waves) appear likely beginning late Thursday, continuing into
the weekend.

&&

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

&&

$$

DISCUSSION.....JM
AVIATION.......Kurimski
MARINE.........JM