311
FXUS63 KGRB 130359
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1059 PM CDT Sat Jul 12 2025

Updated aviation portion for 06Z TAF issuance

.KEY MESSAGES...

- Smoke will impact the region through the weekend. The smoke will
  mix down to the surface at times, reducing visibilities to 2 to
  5 miles, and negatively impacting air quality. 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 06Z TAF Issuance
Issued at 1053 PM CDT Sat Jul 12 2025

Reduced VSBYs due to near-surface smoke will be the primary
aviation concern.

Smoky conditions had improved late this evening, except across far
northern WI. The improvement will be short-lived, as smoke models
show near-surface smoke returning Sunday morning, then lingering
through evening. The thickest smoke will set up across the
northwest part of the forecast area, where vsbys may drop to IFR
at times. Farther southeast, vsbys will probably drop to 4-6sm at
times. Otherwise, expect dry conditions through the period, with
only SCT daytime cumulus development on Sunday.

Light SW-W winds are expected overnight, with gusty SW winds
returning during the daytime on Sunday.

&&

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

&&

$$

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