042
FXUS63 KGRB 071729
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1229 PM CDT Fri Aug 7 2026

Updated aviation portion for 18Z TAF issuance

.KEY MESSAGES...

- There is a marginal (1/5) risk for severe weather this afternoon
  through this evening. Gusty winds and up to 1" hail will be the
  main hazards with any stronger storms.

- Several rounds of showers and storms are expected this weekend
  through early next week, though confidence in storm timing and
  severity remains low.

- Near normal temperatures in the low 80s through most of next
  week.

&&

.DISCUSSION...
Issued at 1224 AM CDT Fri Aug 7 2026

Fog... Dewpoint depressions continue to drop to near or at zero
along the lakeshore overnight as winds attempt to decouple. As
such, expect patchy fog to develop over the next couple of hours.
Confidence decreases into the Fox Valley where dewpoints remain
relatively mixed out. Will continue to monitor for advisory
potential, though CAMs don`t show near as strong of a signal as
yesterday morning.

Rain/storm chances... Marginal risk for severe weather holds
steady this afternoon as compact shortwave and weak cold front
traverse the upper Mississippi Valley. CAM consensus continues to
show a broken line of convection developing over northwest
Wisconsin along the front during peak heating (1,500 to 2,000 J/kg
MLCAPE), progressing over the Northwoods through the evening.
However, biggest question will be whether or not the brunt of the
severe action splits us to the north, where better deep-layer
shear resides closer to the shortwave, and to the southwest where
better moisture return is. NCAR ML guidance shows higher probs
over these areas as an artifact of previous CAM runs. Regardless,
gusty winds would be a threat with any storms that do develop due
to stout inverted-V profiles tapping into 30+ knot winds at the
top of the dry layer. Severe threat diminishes further east.

Not many changes to speak of beyond Friday as several embedded
shortwaves riding the 500 mb wave train bring multiple rounds of
showers and storms Saturday night through early next week. Most
of the moisture/instability look to remain holed up to our
southwest under western ridge; as such, better chances for more
organized convection remain where better thermodynamics are.
However, period to keep an eye on will be Sunday into Monday as
surface low spins up over the Plains and signal for better
instability exists over the western Great Lakes. ML guidance
currently shows 15 to 30% prob severe into portions of central
Wisconsin during this time. Likewise, heavy rain threat remains
conditional and will likely hinge on training storms where the
boundary stalls out. As it appears now, axis of heaviest precip
Sunday into Monday looks to target southern Wisconsin, with more
of a glancing blow to our southern tier of counties. WPC carries
Marginal ERO on days 4 and 5.

Temperatures/smoke... Temperatures to read near seasonal norms in
the low 80s through the better part of next week. Elevated smoke
plume works into northeast Wisconsin preceding cold FROPA today,
though no significant impacts to visibility or air quality are
expected. Elevated smoke to return late Saturday into Sunday.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1229 PM CDT Fri Aug 7 2026

Quite a bit of cloud cover early this afternoon with a SCT-BKN
MVFR/IFR cumulus deck and higher cirrus blowoff from upstream
convection across the region. The cumulus field should eventually
lift to all VFR this afternoon with continued mid and high clouds
streaming in ahead of an approaching area of convection.

A cold front will bring the chance for showers and thunderstorms
later this afternoon into this evening. Greatest chances for
thunder look to be associated with a BKN line of convection over
the central and north-central sites later this afternoon; with a
PROB30 of -TSRA in the TAF from 22Z to 02Z. Storms then diminish
in coverage as they track east, though still worth mentioning in
the east- central TAFs as well. Gusty winds and reductions in
vsbys due to heavy rain will be possible during this time. Cigs
should remain low-end VFR. Prevailing winds increase out of the
southwest this afternoon, gusting to 20 knots. Skies then clear
out overnight with light winds.

&&

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

&&

$$

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

NWS GRB Office Area Forecast Discussion