673
FXUS63 KGRB 141110
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
610 AM CDT Mon Sep 14 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Chilly temperatures in the mid 30s will cause widespread frost
  across northern WI early morning.

- A round or two of heavy rain and storms is expected this
  afternoon through Tuesday. Rainfall amounts of 2 to 3 inches
  are possible across central and east-centrla WI. The severe
  weather threat is low.

- Hazardous conditions for small craft return this afternoon and
  continue into Tuesday. Small Craft Advisories or a Gale Watch is
  in effect this afternoon and tonight. Additional marine
  headlines will be needed on Wednesday due to gusty winds or
  diminishing waves.


- High waves will lead to an increased risk of rip currents at
  Lake Michigan beaches this afternoon into Tuesday afternoon
  where a Beach Hazardous Statement is in effect.

&&

.DISCUSSION...
Issued at 158 AM CDT Mon Sep 14 2026

Forecast for a a round or two of heavy rain this afternoon
through Tuesday morning remains on track. A strong low pressure
system is evident on WV imagery over the northern Rockies early
this morning. This system will progress east into the northern
Plains today with strengthening southerly flow ahead of the low
drawing seasonally high moisture into the region. Expect rain to
initially push into central WI during the early afternoon,
however, the exact timing for the onset of precipitation remains
somewhat uncertain as forecast soundings do show dry air in the
low-levels that will need to be overcome. This initial round will
likely be light to moderate widespread rain that spreads across
the area by afternoon. A second round of rain is then expected
beginning this evenings over central WI as a strong LLJ pushes
noises into the region. This second round is expected to bring a
more focused area of moderate to heavy rain to central and east-
central WI late this evening and overnight. Between these two
rounds of rain HREF LPMM 24hr rainfall totals show a corridor of
2-3" totals south of a line from Wausau to Sturgeon Bay with 0.5
to 1" north of that line. The exact placement of this higher end
corridor may still shift north or south slightly. A few embedded
thunderstorms are possible with this system, but weak instability
keeps the severe threat low. Rain will come to an end from west
to east Tuesday morning high pressure them bringing dry conditions
for the remains of Tuesday and much of Wednesday.

For the remainder of the week a baroclinic zone is expected set up
over or just south of the forecast area. This will keep a 40-70%
chance for showers and occasional thunderstorms Wednesday afternoon
through next weekend, however, it will likely not rain that entire
period. Temperatures will hover near to slightly below normal next
week depending on where the boundary sets up each day.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 610 AM CDT Mon Sep 14 2026

VFR conditions are expected to continue through this morning. Rain
will arrive from the west this afternoon and evening, with scattered
thunderstorms embedded in the large area of rain. Even with the
rain, conditions through about 00z should remain VFR. Southeast
winds will increase, with gusts over 20 kts on this afternoon.

Rain with embedded thunder will continue statewide this evening and
into Tuesday morning. CIGS are likely to drop into the MVFR category
this evening, with areas of IFR CIGS developing overnight central to
north-central WI. Local IFR-MVFR visibility will also occur. The
rain should end late  tonight into early Tuesday morning, but CIGS
will only slowly improve on Tuesday.

&&

.MARINE...
Issued at 158 AM CDT Mon Sep 14 2026

Strengthening southerly winds today will lead to hazardous boating
conditions on Lake Michigan and Green Bay. Strongest winds, with
gale force gusts are expected late this afternoon through Tuesday
morning. During the period waves on Lake Michigan may reach 12+ ft.
While winds won`t be as strong Tuesday afternoon gusts of 20-25kts
will continue to create conditions hazardous to small craft. With
the high waves strong rip currents are also expected to create
dangerous swimming conditions at Lake Michigan beaches.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Frost Advisory until 8 AM CDT this morning for WIZ005-010>013-
018-019-021.

Beach Hazards Statement from this evening through Tuesday
evening for WIZ022.

Beach Hazards Statement from 4 PM CDT this afternoon through
Tuesday afternoon for WIZ040-050.
&&

$$

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

NWS GRB Office Area Forecast Discussion