564
FXUS63 KGRB 041209
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
709 AM CDT Sat Jul 4 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Isolated to scattered showers and thunderstorms are expected at
  times today and Sunday, mainly in the afternoon and evening
  across central and north-central Wisconsin.

- Seasonal summer temperatures are expected for the holiday
  weekend.

- Dry conditions for early next week, with shower and thunderstorm
  chances returning midweek.

&&

.DISCUSSION...
Issued at 254 AM CDT Sat Jul 4 2026

Early Morning Analysis...Radar and satellite imagery early this
morning showed light showers or drizzle falling out of a mid-level
cloud deck over north-central WI, while the remainder of the region
was dry under high to mid-level clouds. However, an remnant lake
breeze off of Lake Superior has made its appearance over
northeast WI with a wind direction change to the north. In the
wake of the lake breeze, isolated showers developed over northern
Door County. Anticipate the showers/drizzle across the north and
the isolated showers over Door County to gradually end before
sunrise. A few rumbles of thunder are possible over Door County
given some present elevated instability, but will remain non-
severe. Additionally, some patchy fog is possible at times across
the region through early this morning.

Today through Sunday night...Look for isolated to scattered showers
and storms at times, mainly during the afternoon and evening. The
energy from a mid-level shortwave progged to move over the Upper
Mississippi Valley/Midwest by late this evening, paired with daytime
instability, will be the driving factors for shower/thunderstorm
activity today. CAMs and other model guidance indicate the
shower/storm activity will mainly be focused over central and north-
central WI, where instability will be highest (1000-1500 J/kg). A
lack in deep-layer shear should prevent any organization from
developing, and would be more pulse-like storms. But, cannot rule
out a few stronger gusts within any thunderstorms. Further east, the
prevailing north/northeast winds in the wake of the aforementioned
lake breeze and lack in instability should keep conditions dry for
today. The shower/storm activity will come to an end as daytime
instability wanes after sunset. For Sunday, the mid-level
shortwave/trough will reside over the area, causing similar
conditions to today with daytime shower and storm activity focused
mainly in central and north-central WI. However, coverage may be
even more limited due to the persistent northeast winds ushering in
drier air across the region. If any shower/storm activity develops
or moves into the area, it would again end as daytime instability
wanes after sunset.

Next Week...Models continue to agree with upper-level ridging
residing over the area for Monday through most of Tuesday before
breaking down from a shortwave sometime midweek. This will result in
dry conditions for Monday and potentially through most of Tuesday
with chances for showers and storms returning midweek. Long range
global ensembles do show instability typical of early July during
this time making stronger storms possible; however, there is no
signal of a higher end severe event within the statistical suite of
guidance.

Temperatures...Seasonable temperatures are expected for today and
Sunday with high temperatures ranging from the upper 70s to low 80s
each day. Slightly humid conditions are anticipated across central
and east-central WI today with dew points in the mid 60s to around
70 degrees, but will lower on Sunday to the low to mid 60s resulting
in more pleasant conditions. Temperatures will then warm back into
the mid to upper 80s through midweek.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 709 AM CDT Sat Jul 4 2026

An area of low clouds producing MVFR/IFR cigs moved into the
east-central WI TAF sites this morning from the north. MTW was
experiencing the most impactful conditions with LIFR cigs and
1/4SM visibility from dense fog. Meanwhile, a few showers
developed in north-central WI early this morning, but should
dissipate over the next few hours with minimal impacts at the RHI
TAF site. Otherwise, VFR conditions prevailed across the area
this morning under mid to high clouds.

Anticipate the MVFR/IFR cigs at the east-central WI TAF sites to
end by late this morning, with the fog lifting at MTW within the
next hour or two. Otherwise, mainly dry conditions today through
the remainder of the TAF period. The exception would be the
potential for isolated showers and storms developing late this
afternoon into this evening over the central and north-central WI
TAF sites. Confidence is low in these showers and storms directly
impacting the TAF sites, so included PROB30 groups for now.

North to northeast winds of 5 to 15 kts are expected today,
becoming light overnight.

&&

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

&&

$$

DISCUSSION.....Kruk
AVIATION.......Kruk

NWS GRB Office Area Forecast Discussion