820
FXUS63 KGRB 032330
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
630 PM CDT Fri Jul 3 2026

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- Isolated to scattered showers and thunderstorms are expected at
  times this afternoon into this evening, mainly across northern
  WI.

- Additional chances for showers and thunderstorms are expected
  throughout the holiday weekend.

- Seasonal summer temperatures are expected for the holiday
  weekend.

&&

.DISCUSSION...
Issued at 126 PM CDT Fri Jul 3 2026

Rest of Today...A subtle short-wave passing over the region along
with remnant outflow boundaries floating around has lead to an area
of scattered showers across central and east-central WI that will
continue through this afternoon. RAP analysis does show enough weak
elevated instability for these showers to produce isolated lightning,
however, radar and satellite trends over the past hour have shown no
imminent signs of lightning. Another area of showers and storms is
possible across northern WI this afternoon and evening as a lake
breeze moves south of Lake Superior. Again, there is enough
instability to support lightning, however, with a lack stronger deep
layer shear don`t expect any stronger more organized storms to
develop.

Shower and Storm Chances This Weekend...Lingering boundary
(lake/outflow) scattered across the forecast area Saturday morning
may provide the focus for scattered showers with embedded
thunderstorms. However, confidence in showers at any given location
is low so have limited PoPs through the morning to 20-40%.
Precipitation chances do increase into the afternoon and evening as a
middle level short-wave, tracks over the region. Highest
precipitation chances (50-70%) are across central WI Saturday
afternoon with lower chances (30-50%) closer to the lakeshore and
into north and northeast WI. MUCAPE values of 800-1200 J/kg will
make isolated thunderstorms possible during the afternoon and
evening, however, with weak deep layer shear the chance for stronger
organized storms is low (~10%). CAM ensembles point towards a second
trailing shower-wave pass over the region Saturday night into Sunday
leading to lingering shower and thunderstorm chances (20-40%)
through Sunday morning before precip chance dry up Sunday afternoon.

Dry to Start Next Week...Global ensembles and longer ranger ML
models are in generally good agreement than an upper ridge will be
building over the upper Midwest during the beginning of next week.
This will bring largely dry conditions to the forecast area Monday
and Tuesday. As the aforementioned ridge pushes east during the
middle of next week large scale troughing is expected to develop.
This will lead to increasing chances for showers and thunderstorm
Wednesday into Thursday. 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.

Temperature Trends...This weekend temperatures are forecast to trend
near seasonal averages with highs in the upper 70s to low 80s
Saturday and Sunday.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 311 PM CDT Fri Jul 3 2026

MVFR cu field continues to scatter out this evening, leaving mid
clouds in its wake. SCT showers and storms are already developing
along a lake breeze sinking south off of Lake Superior this
evening and are expected to continue into tonight; have thus
opted to include a PROB30 mention for -TSRA in the RHI TAF where
thunder is most likely. Showers will continue to diminish in
coverage overnight, though may linger into Saturday morning. Brief
lowering of cigs to MVFR will be possible if a shower or storm
moves directly over a terminal. Remnant moisture near the surface
may then result in patchy fog development across the forecast
area late tonight into Saturday morning, though confidence
remains low in fog coverage and density. Will limit any reductions
in vsbys to MVFR.

Winds will start out of the south/southwest, eventually veering to
east/northeast behind the lake breeze Saturday morning. Winds may
gust to 15 knots near MTW Saturday afternoon.

&&

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

&&

$$

DISCUSSION.....GK
AVIATION.......Goodin

NWS GRB Office Area Forecast Discussion