392
FXUS63 KGRB 161741
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1241 PM CDT Thu Oct 16 2025

Updated aviation portion for 18Z TAF issuance

.KEY MESSAGES...

- Temperatures will trend warmer late this week, with highs in
  the middle 60s to middle 70s Friday into Saturday.

- Periodic rain and a few thunderstorms expected today through
  Sunday. Heavy rainfall is possible in the Fox Valley and
  lakeshore areas late Saturday night into Sunday morning, with a
  20 to 40 percent chance of amounts greater than 1 inch.

- Windy periods also expected late this week, with south winds
  gusting to 25 to 30 mph on Friday, and northwest winds gusting
  to 25 to 35 mph on Sunday.

&&

.DISCUSSION...
Issued at 427 AM CDT Thu Oct 16 2025

Upper level ridging and Canadian high pressure combined to keep
the forecast area dry early this morning. However, clouds covered
the southwest third of GRB CWA, and the regional radar mosaic
already showed a few showers crossing the MN/WI border. The
showers were developing in a broad area of WAA, where PWATs
were increasing to 1.25-1.50 inches.

Low pressure will track from the Central to Northern Plains today
through this evening, then into Manitoba late tonight through
Friday night. Initial bands of showers will likely weaken as they
approach this morning, but increasing WAA and moisture advection
should bring scattered showers and possibly a storm or two to most
of the region this afternoon/early evening. There will be a
better chance of showers across the northeast half of the forecast
area later this evening into the overnight hours, as a 30 to 40
knot low-level jet develops and a warm front lifts through the
area. A brief break in the rain is expected to occur Friday
morning as the warm front lifts north, but the arrival of a
weakening cold/occluded front will bring showers and a few storms
to NC/C WI Friday afternoon, and to the rest of the region Friday
night. Breezy south winds gusting to 25 to 30 mph will help boost
Friday`s high temperatures into the upper 60s to middle 70s. This
will be the warmest day of the week.

Another cold front arrives Saturday into Saturday night, with a
potent negatively-tilted short-wave inducing strong cyclogenesis
along the boundary as it moves through WI late Saturday night
into Sunday morning. This system will spread significant rainfall
across the forecast area, possibly heavy in the Fox Valley/lakeshore
areas, where there is a 20 to 40 percent of amounts in excess of
1 inch. The deepening low will also generate strong northwest
winds as it departs on Sunday, with gusts to 25 to 35 mph expected
inland, and a 30 to 50 percent chance of Gales on Lake Michigan.

Rain tapers off Sunday afternoon, with drier weather returning
Sunday night into Monday. Another cold front and short-wave
arrives Monday night into Tuesday, along with a chance of rain.
Small precipitation chances linger into mid-week, especially over
the northeast half of the forecast area. More seasonable
temperatures return during this period.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1241 PM CDT Thu Oct 16 2025

A deck of primarily VFR based clouds has spread over most the region
this morning, however, low-level dry air associated with a surface
high centered over lower Michigan has held rain showers off to the
west. Do expected these showers to slow advance into central
Wisconsin this afternoon, however, with the dry air in place have
slowed the arrival of -SHRA at AUW, CWA, and RHI. Along with the
rain a period of MVFR cigs will also likely push into central
Wisconsin this afternoon and linger across northern Wisconsin
through much of the overnight period.

A warm front lifting across the area later this evening and
overnight may bring another round of showers, however, guidance has
shifted the target area for rain further to the north and east
(along the WI/UP border).

An strengthening low-level jet tonight will also create a period of
LLWS overnight, mainly across central and northern WI. Southerly
surface winds are also expected to become breezy with gusts reaching
15-20kts.

&&

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

&&

$$

DISCUSSION.....Kieckbusch
AVIATION.......GK