072
FXUS63 KGRB 071130
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
630 AM CDT Fri Aug 7 2026

Updated aviation portion for 12Z 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 12Z TAF Issuance
Issued at 600 AM CDT Fri Aug 7 2026

Vsbys have gradually come down in/near MTW over the past several
hours as lakeshore fog thickens, so have carried TEMPO group for
1/2 SM vsby through 14Z. Confidence in fog development decreases
toward the Fox Valley, though have still opted to include mention
of BR for GRB and ATW.

SCT fair weather cu field should begin popping within the next
few hours, becoming more widespread over the north by early this
afternoon. Mid clouds then increase mid-afternoon as a cold front
approaches from the west, bringing our next chances for
showers/storms. Greatest chances for thunder look to be associated
with a BKN line of convection over the central and north-central
sites later this afternoon; have thus added PROB30 inclusions 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.

&&

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

&&

$$

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

NWS GRB Office Area Forecast Discussion