527
FXUS63 KGRB 050630
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
130 AM CDT Wed Aug 5 2026

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Isolated to scattered showers (30 to 50% chance) continue
  through this morning as a slow-moving cold front sinks south.

- Near normal temperatures in the 80s through the weekend.

- Several rounds of showers and storms will be possible Friday
  through Sunday, though confidence in storm timing and severity
  remains low.

&&

.DISCUSSION...
Issued at 1154 PM CDT Tue Aug 4 2026

Shower/storm chances... Latest surface obs show the cold front
draped over southeast Wisconsin early this morning, resulting in
weak radar returns percolating mainly in the Fox Valley eastward.
CAMs show additional shower activity persisting north of the
slow-moving boundary through this afternoon as transient
shortwave energy passes over Wisconsin. A rumble or two of thunder
will be possible mainly over east-central Wisconsin later this
morning, though chances diminish into the afternoon.

Not many changes to speak of regarding late week rain/storm
chances as we remain on the northeast periphery of western
ridge/heat dome. Most long-range models have the reservoir of
instability under the ridge remaining off to our south through the
weekend, which would shunt better chances for more organized
convection to southern Wisconsin and northern Illinois.
Nevertheless, several perturbations embedded within the mean flow
are progged to interact with a surface low as it tracks over the
upper Mississippi Valley, kicking off several rounds of shower and
storm activity across the forecast area Friday afternoon through
Monday. ML guidance continues to paint broad 5 to 15% probs over
the Midwest on Days 4, 5, and 6. Worth mentioning is the fact that
storm predictability remains low this far out, with the synoptic
pattern wont to change over the next couple of days. Will continue
to monitor for any severe weather potential.

Temperatures/smoke... Temperatures to read near normal in the low
to mid 80s through the weekend as upper flow flattens out and
weakens. Humidity levels will be comfortable, with dewpoints
reading mainly in the low 60s. Some elevated smoke may linger
across the area through this evening as the front slowly treks
south, though no significant impacts to visibility or air quality
are expected.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1024 PM CDT Tue Aug 4 2026

A slow moving cold front will gradually sag south over east-
central WI overnight. Thunderstorm activity should generally
remain south of OSH and MTW overnight but a few scattered showers
will be possible though difficult to have confidence with the
precise timing.

Confidence is increasing, however, for showers to move across
east-central WI on Wednesday morning. As these showers arrive,
ceilings are forecast to fall from VFR into MVFR or high end IFR
range (MTW in particular). Then decreasing clouds are expected
from 20Z Wed to 00z Thu over the Fox Valley and Lakeshore.

Over central and north-central WI, a broken mid-deck will persist
through much of the night. Removed the potential for ground fog
and the IFR visibilities from the previous TAF issuance at RHI. A
widespread fair weather cloud field is then expected to pop with
daytime heating around 16-17z with bases around 4-5 kft.

The clearing trend will continue on Wed night leaving VFR
conditions by the end of the TAF period.

&&

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

&&

$$

DISCUSSION.....Goodin
AVIATION.......MPC

NWS GRB Office Area Forecast Discussion