072
FXUS63 KGRB 140641
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
141 AM CDT Fri Aug 14 2026

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Scattered showers (30-55%) late tonight through Saturday
  afternoon. Latest trend is downward for rain chances and rain
  amounts on Saturday.

- Another round of showers (30-50%) and a few thunderstorms
  (10-20%) Saturday night as cold front moves through. Locally
  heavy rain possible.

- Drying out later Sunday into Monday with next chance for showers
  and some storms Tuesday into Wednesday.

&&

.DISCUSSION...
Issued at 140 AM CDT Fri Aug 14 2026

Day today, some showers arrive late tonight: Weak high pressure
overhead with pockets of mid cloud and locally dense fog. Thus far
the fog is variable in coverage to have anything more than SPS
out, but will monitor to see if a Dense Fog Advisory is needed
anywhere. A lull in cloud cover this morning, then clouds increase,
thicken late today ahead of southern stream shortwave that arrives
late tonight. Easterly winds result in warmest readings today
central to north-central WI with highs in the lower, maybe mid
80s. Few showers make it into southern tier of counties very late
tonight ahead of the wave.

Showers/Storms Saturday and Saturday night: Trend that is emerging
is most guidance (except especially the NAM) is to keep majority
of widespread showers on Saturday to the south closer to the
higher instability and convergence on nose of LLJ. This shows up
nicely when looking at HREF 1hr probs of 0.01" which shows higher
probabilities staying over far southern WI, northern IL during
the morning. Increasing moisture and lift on the north edge of
this could still produce scattered showers, with the greatest
focus southern Fox Valley to the lakeshore. If this trend continues
though, some locations could stay dry during the daytime on Saturday,
which looked very unlikely a couple days ago. Main front does
swing through on Saturday night with primary shortwave over Lake
Superior. This is likely when most locations will see at least
scattered showers. Given boundary is interacting with PWATs over
1.8" (95+ percentile) and slower MBE vectors are forecast,
locally heavy rain may occur Saturday night.

Dry later Sunday into Monday: Front clears eastern WI by Sunday
morning. A few showers may linger during the morning, but mainly a
dry day is expected. Looks kind of breezy with peak gusts over 20
mph at times as winds shift northwest. Despite being behind the
front, it could actually be warmer on Sunday with more sunshine
and mixing. Not as humid as Saturday, but dewpoints will still
linger into the mid 60s over east-central most of the day. Monday
will be noticeably less humid across the board.

Next chance for rain is Tuesday...Northwest flow brings another
shortwave trough and cold front through leading to next chance
for organized showers and some thunder Tuesday. Greatest instability
Tuesday afternoon remains southwest of our area, so risk for
severe storms looks lower which aligns with various ML
projections that shows greater signal southern MN into IA.
Models/ensembles are picking up on another wave sliding in from
the west interacting with the frontal boundary to keep showers and
some storms lingering later Tuesday night into Wednesday. With
PWATs up to 1.5 thrown into the mix, probabilities of 0.5 inch/1.0
inch of QPF have steadily increased over the last few runs. ECMWF
EFI/SOT now has some signal for heavy rain. WPC is also now
indicating a Marginal to Slight (level 1/2 of 4) for excessive
rain during this time. As we saw with the evolution of this weekends
higher risks that eventually shifted south, these areas can shift
with time, but will be something to watch as we get closer to this
time frame.

Cooler air push behind this system for the end of the week with
highs settling into the lower to middle 70s.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1041 PM CDT Thu Aug 13 2026

Patchy areas of fog are beginning to develop across parts of east-
central WI late this evening. Periods of IFR vsbys are possible at
GRB, ATW, and MTW, through about 10Z.  Once the fog clears VFR
conditions are expected for the rest of Friday.

Light and variable winds are expected overnight. Friday easterly
winds will increase gradually with gusts up to 15kts possible.

Beyond the TAF period a round of scattered showers and isolated
storms is expected to move into the region Saturday morning. Period
reductions in visibility along with lightning are expected to be the
main aviation impacts.

&&

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

&&

$$

DISCUSSION.....JLA
AVIATION.......GK