354
FXUS63 KGRB 122011
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
311 PM CDT Sat Jul 12 2025

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- A strong storm will remain possible this afternoon across far
  eastern WI. Gusty winds are the main threat.

- Smoke will spread across the region this weekend, reducing
  visibilities at times. Surface smoke is possible. An Air Quality
  Advisory is in effect through noon on Monday.

- Next round of active weather arrives Tuesday afternoon into
  Wednesday.

&&

.DISCUSSION...
Issued at 311 PM CDT Sat Jul 12 2025

Precipitation/Thunderstorm Chances: Despite the fairly decent
instability (up to ~1500 J/kg) and deep layer shear (30-45 kts), a
weak capping inversion and limited surface convergence, along
with the best upper forcing and steeper lapse rates trailing the
front, is limiting storm intensity and coverage this afternoon. As
a little more heat/instability builds and a weak cool front works
east, expect the broken line of showers and isolated storms to
move across far eastern WI. With DCAPE up to 700 J/kg (although
the highest values are behind the line of showers), any organized
storm could produce some gusty winds, along with brief torrential
rain. No flooding is expected as the storms will be quick movers.
The line will exit to our east by 5-6pm, with dry conditions
expected tonight.

A weak boundary will approach central and north central WI late
on Sunday, which could produce a stray shower or storm. Have keep
the slight chance (20%) PoPs in the early evening. Another very
small chance of a shower on Monday as this boundary lingers in the
area and a weak shortwave crosses the state, but kept most of the
area dry for now. A dying complex of storms will make a run at
north central WI early Tuesday, with better chance for widespread
shower and storms later Tuesday into Wednesday as the boundary
sags over the area, instability and moisture pool south of the
boundary, a LLJ points into the region, and a couple quick moving
shortwaves within the zonal upper flow.

Smoke: Satellite showing a large area of smoke across the Upper
Midwest, along with many surface reports of haze. Webcams also
showing a pretty milky/hazy sky. HRRR/RAP/Canadian smoke guidance
all showing the elevated smoke over the region into Sunday, with
another batch possible on Monday. The smoke could make it to the
surface at times, especially across northern WI. Very poor air
quality readings have been observed across MN today and should
shift east tonight into Sunday. An Air Quality Advisory remains
in effect through noon on Monday.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1253 PM CDT Sat Jul 12 2025

A mix of VFR and MVFR conditions will continue this afternoon. A
line or two of isolated to scattered showers and storms is
expected to move east across eastern WI this afternoon, but
overall storm coverage looks to be limited, due to a weak capping
inversion and limited surface convergence, so will keep the
thunder threat confined to PROB30 groups and add a TEMPO group if
necessary. As the line exits to the east, dry conditions are
expected tonight into Sunday morning.

Large area of smoke will spread into the Great Lakes today into
tonight. Upstream VSBYs mainly in the 2-5SM range, so have added
smoke into all the TAF sites.

&&

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

&&

$$

DISCUSSION.....Bersch
AVIATION.......Bersch