Pensaukee, Wisconsin Weather Forecast Discussion

870
FXUS63 KGRB 092332
AFDGRB
Area Forecast Discussion
National Weather Service Green Bay WI
632 PM CDT Tue Sep 9 2025
Updated aviation portion for 00Z TAF issuance
.KEY MESSAGES...
- Rain and a few storms continue across far north-central
  Wisconsin. Additional rain (30-50% chance) arrives in the late
  evening for central Wisconsin.
- Additional potential (20-40% chance) for showers on Wednesday,
  mainly west and north of the Fox Valley and Green Bay areas.
- Conditions hazardous to small craft, along with dangerous
  swimming conditions, expected on the bay and Lake Michigan
  through this afternoon/evening.
- Chances for showers and thunderstorms return for the start of
  the weekend.
&&
.DISCUSSION...
Issued at 216 PM CDT Tue Sep 9 2025
Shower and storm activity continue across far north-central
Wisconsin at the leading edge of the warm air this afternoon.
Generally, the rain has made a slow shift east and south, but will
likely continue into the mid to late afternoon. The rain may see
more breaks develop in the evening as the sustaining low level jet
weakens, but kept at least some pops (20-40%) in the area to
account for lingering activity, especially with some signs of
additional development further to the west along the leading edge
of the warm air. Rain amounts under these storms could still get
to a few tenths, but will be heavily localized to the northwoods.
A cold front accompanied by an upper shortwave feature currently
visible on satellite and radar will also continue to work its way
towards the region by the late evening hours. Although this is
forecast to weaken on its way into our area, scattered (30-50%)
shower activity seems likely across central Wisconsin by Wednesday
morning. The rain across central and north-central Wisconsin will
also provide a window for fog development during the overnight
period, so kept fog in the forecast for much of central to north-
central Wisconsin.
Wednesday precipitation trends are less certain. Some guidance
suggests the weakening cold front and shortwave will lead to
precipitation departing the region by the late morning. That said, weak
surface instability on model soundings, ample moisture, and
lingering upper support as the shortwave crosses the region in the
afternoon does suggest at least scattered shower activity.
Therefore, leaned away from a dry forecast and kept at some low
pops (20-30% chance at any one location) in the forecast to
account for some lingering light shower potential. Overall, the
better probability remains north and west of the Fox Valley,
especially in the afternoon where again there are signs of maybe
a rumble of thunder for far northern Wisconsin. However, if
anything does stay organized a little longer, a brief sprinkle
will be possible across the Fox Valley as well.
High pressure builds into the region as the front shifts
southeast Wednesday night, and should bring dry weather through
most of Friday. The high pressure system will edge east Friday
night into Saturday, allowing the front to return as a warm
front. Scattered showers and thunderstorms are expected develop
as this occurs. Dry weather should return late in the weekend as
strong ridging aloft builds across the western Great Lakes.
Temperatures will remain close to normal through midweek, then
rise above normal Friday into Saturday, with highs reaching the
upper 70s and lower 80s in most areas.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 625 PM CDT Tue Sep 9 2025
Scattered showers and storms continue to impact north-central
Wisconsin this evening, bringing locally MVFR cigs and scattered
thunder to RHI. Opted to include a PROB30 group for thunder in
the RHI TAF late this evening as radar returns continue to fill
in to the west and modest instability persists. Shower activity
then spreads to the central Wisconsin sites late tonight into
tomorrow morning, though have withheld thunder due to low
confidence.
Remnant moisture from aforementioned rainfall will result in
potential for fog development, locally dense, across north-central
Wisconsin late tonight into Wednesday morning. IFR to LIFR vsbys
will be possible near RHI if dense fog develops. Fog should then
scatter out by daybreak, with conditions gradually improving to
VFR by Wednesday afternoon.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
Beach Hazards Statement until 10 PM CDT this evening for WIZ022.
&&
$$
DISCUSSION.....Uhlmann
AVIATION.......Goodin

NWS GRB Office Area Forecast Discussion