769
FXUS63 KGRB 091709
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1209 PM CDT Sun Aug 9 2026

Updated aviation portion for 18Z TAF issuance

.KEY MESSAGES...

- Showers and storms return later this morning. Main severe risk
  remains over southern Wisconsin, though gusty winds and heavy
  rain will be possible with any storm activity.

- Additional rounds of showers and storms through the middle of
  next week, though confidence in storm timing and severity
  remains low.

- Slightly cooler in the 70s today. High temperatures in the low
  80s early to mid-week, followed by a cooling trend late next
  week.

&&

.DISCUSSION...
Issued at 1135 PM CDT Sat Aug 8 2026

Rain/storm chances... Prior forecasts remain on track as prevailing
northwest flow containing several embedded shortwaves brings
periodic chances for rain/storms through the better part of next
week. Greatest opportunity for heavy rain and storms look to be
later this morning as surface low crosses the upper Mississippi
Valley, though severe chances remain nebulous. Better jet dynamics
remain off to our south during this time, and environment looks
relatively capped from around 850 to 700 mb up into northeast
Wisconsin. Regarding heavy rainfall potential, LREF probabilistic
guidance only shows a 10 to 15% chance for receiving 1" of rain
across our southern tier of counties through Monday morning.
However, timing of the boundary will play a large role in whether
or not we can get excessive rain, as some long-range models hint
that the front might stall out over southern Minnesota into
central Wisconsin. In this case, we would mostly rely on training
storms to get heavy rain across portions of central to east-
central Wisconsin.

Next noteworthy chances for rain/storms look to come late Monday
into Tuesday, though similar pattern emerges where better
dynamics look to remain holed up to our south in proximity to the
front. Suspect that any storms that are able to get going would
be more diurnally-driven Tuesday afternoon. More or less rinse and
repeat for Wednesday until the front shifts far enough south that
we`re afforded a brief dry spell.

Extended... Temperatures to read generally in the low 80s through
mid-week as upper flow flattens out and weakens. Signal for a
cooler and drier pattern shift then exists late next week as
polar airmass builds to the north and is transported south via
troughing regime. Highs will fall into the 70s for most during
this time.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1209 PM CDT Sun Aug 9 2026

An approaching cold front will bring a continued chance for
showers and thunderstorms this afternoon, mainly south of KRHI.
Conditions will generally be VFR, dropping to MVFR in
precipitation. Conditions then return to VFR by this evening as
the showers diminish. Abundant low level moisture from the
precipitation today should lead to patchy MVFR/IFR fog overnight
into early Monday morning. Any fog should burn off a few hours
after sunrise Monday, with VFR conditions the rest of Monday.
Otherwise, southerly winds gradually veer to northerly into
tonight, gusting to 15 knots this afternoon. Light winds then
expected overnight into Monday.

&&

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

&&

$$

DISCUSSION.....Goodin
AVIATION.......Kurimski

NWS GRB Office Area Forecast Discussion