771
FXUS63 KGRB 222328
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
628 PM CDT Fri Aug 22 2025

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- Rain and thunderstorm chances move through this evening and
  exit eastern WI overnight. Isolated strong storms impact
  northern WI through early evening.

- First glimpse of early fall expected this weekend into early
  next week.

&&

.DISCUSSION...
Issued at 400 PM CDT Fri Aug 22 2025

A cold front was moving into northwest WI this afternoon, but
a line of convection had formed well in advance in association
with an MCV, and was moving into NC WI. There had been some
indications of wind potential with short bowing segments within
the line, but so far, the peak wind report had been 31 kts at
IWD.

Overall, the severe threat appears low for the rest of the
afternoon and evening, as cloud cover has limited instability,
deep layer shear is only 25-30 kts over far northern WI, and DCAPE
values have dropped to 700-900 j/kg. The bulk of the shower and
thunderstorm activity will move through far northern WI through
early this evening, but isolated to scattered development should
occur farther south/east as the cold front moves through during
the evening and early overnight hours. Expect some clearing to
occur later tonight, with lows ranging from the middle 50s
northwest to the middle 60s southeast.

An upper low over Ontario will drift toward Hudson Bay over the
weekend and into early next week. Numerous short-waves will
rotate through the western Great Lakes during the Saturday through
Monday period, bringing periodic light shower chances. The
strongest wave will move through on Sunday, when showers chances
will exist regionwide, and a few thunderstorms may even occur.
Otherwise, most of the showers will be concentrated over far NC WI
and northern Door County, where NW flow off the Great Lakes will
locally enhance moisture. Temperatures will even get cold enough
to support some light lake-effect rain showers in these same areas
late Sunday into Monday.

Drier conditions look to arrive by Monday night or Tuesday, but
there is concern that a back door cold front will sag into the
area Wednesday night into Thursday and bring some showers. The
blended model pops are not bullish on precipitation potential at
this time, but would not be surprised pops increase with
subsequent forecasts.

Much cooler temperatures arrive for the late weekend into early
next week, with highs only reaching the upper 50s and 60s Sunday
and Monday. Depending on cloud cover, where could be some
potential for patchy frost in the Northwoods Monday night and
Tuesday night. Moderation will occur mid to late week, with
temperatures returning to near normal late.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 628 PM CDT Fri Aug 22 2025

A cold front (or prefrontal trough) is draped across north-central
to southwest Wisconsin at 23z. Showers and thunderstorms have
weakened across north-central and far northeast WI early this
evening. Additional scattered shower activity has developed across
western Wisconsin and poised to move across central WI beginning
around the start of the taf period. An isolated thunderstorm is
possible but no sign of deep convection developing over the past
few hours.

The cold front/prefrontal trough will move across the region this
evening, bringing scattered showers and a short period of MVFR
ceilings to north-central and central WI. Confidence is lower
that showers will reach eastern WI, so continued the prob30 groups
from the previous forecast. Spotty IFR ceilings exist around
Manitowish Waters, but coverage doesn`t look widespread enough to
make it into RHI.

After a period of clearing overnight, passage of the secondary
front (or actual cold front) will bring ample low level moisture
and steepen low level lapse rates for Saturday. This should result
in a widespread strato-cu spreading from northwest to southeast
across the area during the morning. Brief MVFR cigs look possible
over north-central WI with initial development on Saturday
morning.

Northwest winds will become gusty to 20 kts on Saturday.

&&

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

&&

$$

DISCUSSION.....Kieckbusch
AVIATION.......MPC