767
FXUS63 KGRB 170009
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
709 PM CDT Thu Jul 16 2026

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- Air quality and visibility will continue to be degraded by smoke
  from wildfires burning across northern Minnesota and southwest
  Ontario through at least Friday.

- There is a 20-45% chance for isolated showers and storms across
  central Wisconsin late tonight; no severe storms are expected.

- Isolated to scattered thunderstorms are expected Friday
  afternoon and evening (60-80% chance). A few storms could become
  strong to severe, mainly across northern WI, with threats of
  damaging wind gusts, hail, and locally heavy rain.

- Another round of thunderstorms is possible (40-60% chance)
  Monday. Predictability of any of these storms becoming severe is
  low.

&&

.DISCUSSION...
Issued at 1252 PM CDT Thu Jul 16 2026

Smoke Trends...Widespread smoke from wildfires burning across
northern Minnesota and Ontario will continue to affect the region
through at least Friday as light winds remain north to
northeasterly. Visibility may drop as low as 1 mile at times. An
Air Quality Advisory from the Wisconsin DNR also remains in effect
until at least noon Friday, and may need to be extended for at
least parts of the forecast area.

With upper-level flow remaining predominantly northwesterly
through this weekend and into next week periods of smoke will be
likely over the next several days. However, surface winds will
briefly become southerly Friday which could shove much of the
smoke east allowing for at least some improvement to visibility
and air quality.

Thunderstorm chances...A nearly stationary surface boundary
generally along the I-94 corridor is currently in place.
Southwest of this boundary moderate to strong destabilization is
expected to develop this afternoon. This will create at least a
low-end (20-25% chance) for a few isolated thunderstorms across
central Wisconsin tonight. However, with weak forcing/surface
convergence and lack of stronger deep layer shear the risk for any
stronger storms is low.

Storm chances do uptick on Friday (60-80% chance) as a series of
short-waves are progged to pass over the region. This activity
will draw the aforementioned stalled boundary northward as a warm
front during the day Friday. CAMs generally show this warm front
advancing as far north as Lake Superior by Friday afternoon with
strong destabilization (MLCAPE 1500-2000 J/kg) to its south.
Recent CAMs generate showers and thunderstorms ahead of the warm
front across north-central Wisconsin Friday morning. These storms
are expected to remain below severe limits as instability will be
fairly limited.

Forcing for ascent and deep layer shear are expected to increase
late Friday afternoon into the evening as a more dynamic short-
wave dives across Lake Superior and drags a cold front across the
forecast area. This will create at least a marginal environment
for strong to possibly severe storms to develop, mainly across
northern Wisconsin and the UP. Storm mode is relatively uncertain
at this point, but if any discrete supercells are able to develop
up to one inch hail, damaging wind gusts, and locally heavy
rainfall would be possible. Forecast hodographs from north-
central WI also show enough low-level curvature to support a low
probability tornado threat. That threat is expected to decrease
with eastward extent as storms may tend to grow more into a
cluster. One note for this period is smoke trends will be import
to monitor Friday in regards to the degrees of destabilization
that is able to occur.

Ridging will return largely dry conditions to the region for this
weekend. Another chance (40-60%) for showers and storms arrives
Monday with the passage of another front and upper level speed
max. Predictability on if any storms become severe is low.

A surface ridge will then generally bring dry conditions to the
region for the rest of next week.

Temperatures...Temperatures will remain above average into early
next week, although cooler than prior days. Peak heat indices at
times may reach 90 in spots but thicker smoke may limit daytime
temperatures and heat indices to some degree over the next few
days.

A cooler, drier airmass is favored by the middle of next week
within the deeper northwesterly flow aloft.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 709 PM CDT Thu Jul 16 2026

Smoke will continue to be the main aviation impact tonight into
Friday morning. The smoke will continue to create IFR/MVFR vsbys
into tonight, but as winds turn S/SW on Friday, the smoke will
exit the area from southwest to northeast through the late morning
and afternoon. Surface obs may also continue to show MVFR
ceilings at times, however, these ceilings are tied to smoke
rather than clouds. Other VFR/MVFR clouds will push across the
area this evening associated an the area of showers and storms to
the west.

In addition to the smoke, the area of showers and storms over
west central WI will continue to slowly work northeast toward the
region. Have added some TEMPO groups for showers/storms later
tonight into early Friday. But confidence remains low if any
thunder will impact the TAF sites. Will continue to monitor
trends.

Light winds are expected tonight, with S/SW winds of 5-15 kts
expected on Friday.

.KOSH...

IFR visibilities from smoke will continue to impact KOSH tonight
into Friday morning, then the smoke will move out of the area
Friday afternoon. The thicker smoke is likely to move back into
the area at times this weekend as flow turns back to the north.
Surface obs will also continue to show MVFR ceilings at times,
however, these ceilings are tied to smoke rather than clouds.
Other VFR/MVFR clouds will push across the area this evening
associated with the area of showers and storms to the west.

The latest models continue to indicate that scattered light
showers and isolated storms are possible after midnight through
Friday morning. Will introduce a TEMPO group for showers from
09-13z, but spotty additional activity is possible later in the
day. But most of the day does look dry.

Light winds are expected tonight, with S/SW winds of 6-13 kts
expected on Friday.

&&

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

&&

$$

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

NWS GRB Office Area Forecast Discussion