023
FXUS63 KGRB 231749
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1249 PM CDT Thu Jul 23 2026

.KEY MESSAGES...

- Quiet and comfortable weather continues through Friday morning.

- Increasing southerly winds on Friday afternoon and evening
  will lead to hazardous boating conditions for small craft and
  an increased risk for rip currents on Lake Michigan. Beach
  Hazards Statement in effect for Door County and Small Craft
  Advisory in effect for

- Warmer temperatures and higher humidity return over the weekend
  into early next week, with high temperatures climbing into the
  upper 80s to lower 90s and heat indices reaching into the middle 90s.

- Multiple rounds of thunderstorms will be possible Saturday
  through Monday. The highest potential for organized
  thunderstorms is expected on Sunday afternoon and evening and
  possibly again Monday.

&&

.DISCUSSION...
Issued at 1245 PM CDT Thu Jul 23 2026

Today through Friday...

High pressure in northern IL will slide southeast today and
gradually slide east across the southern Great Lakes region
through today. The core of the surface high will shift to the
NE US but the high pressure will remain entrenched much further
west across WI. In the upper levels we will remain in between
the ridge to the west and trough to the east. While there should
be some activity aloft with various shortwaves the conditions
will be much too dry for anything to come of the upper level
forcing. Though we will some diurnal cumulus given

The high pressure will finally start to exit Friday with lower
pressure pushing in from the west as the ridge aloft nudges
toward the region. No real weather concerns for this period as
we remain dry.

It is worth mentioning that Beach Hazards Statement is now in
effect for Friday late afternoon and evening for Door County as
breezy onshore winds may yield nearshore wave heights from 3-5
feet. Expansion to the south may be needed.

Friday night through Wednesday...

As the ridge nudges into the region this weekend expect
temperatures to warm back up with a return of humid conditions,
but also a return of precip/storm chances. Saturday will carry
minor chances across far northern WI late Friday night into the
day Saturday with a weak embedded shortwave sliding down the
ridge. There currently looks to be enough moisture and forcing
to bring some precip with some instability in the region likely
allowing for some storms as well. The chance for stronger storms
is really predicated on whether these storms have enough lift to
reach the LFC but if any do, 500-1500 J/kg of instability
paired with 40-50kts of 0-6km shear suggests we could at least
gets some hailers though given the timing storms would likely be
elevated.

Sunday and Monday will be warmer with highs in the upper 80s to
low 90s with multiple chances for storms for northern WI where
Sunday will feature a warm front (strong WAA) as the primary
forcing should allow for high instability and a decent LLJ will
bring in enough shear to bring some severe weather concerns.
Instability will climb to at least 2000-3000 J/kg with strong
deep layer shear of 40-55kts with most of the low level helicity
coming in the lowest 1 km. There will be additional chances for
Monday with very similar conditions. However, the uncertainty
remains fairly high for this period with models kind of all over
the place regarding placement of the forcings and the initiation
of potential convection but generally both days have a chance
for strong to severe storms but the details are still fuzzy on
exactly what could be expected. Otherwise increased uncertainty
toward midweek but the upper levels generally show the ridge
reverting west a tad with weaker high pressure over the region
and several upper level shortwaves rolling through. This
suggests that things could very easily become active for this
period despite limited potential shown in models at this time as
no feature truly stands out at this time.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1230 PM CDT Thu Jul 23 2026

Little to no impacts to aviation are expected throughout the TAF
period as high pressure continues to shift to the east. VFR cu
field with bases at around 5 to 6k ft AGL has already begun
percolating over northeast Wisconsin this afternoon, which should
lift to around 6 to 8k ft within the next few hours. Clouds then
scatter out after sunset, giving way to mostly clear skies
overnight. Winds continue to back to the southwest this afternoon,
remaining under 10 knots through Friday afternoon. Fair weather
cu once again builds late Friday morning.

.KOSH...

SCT fair weather cu with bases at around 6k ft have started
popping in/around OSH early this afternoon. Cloud bases should
continue to rise to around 6 to 8k ft AGL later this afternoon
into this evening, before dissipating after sunset. Mostly clear
skies are then expected overnight, with a cu field forecast to re-
develop late Friday morning.

Winds have begun shifting to the southwest as of early this
afternoon, remaining under 10 knots. Winds then increase to around
10 knots Friday afternoon, with gusts to 15 knots possible.

&&

.MARINE...
Issued at 1245 PM CDT Thu Jul 23 2026

Lighter winds and lower waves in our marine zones as higher
pressure has settled in over the southern Great Lakes region.
Winds will remain light in the waters into Friday before a
brief period of higher winds on the northeast side of Lake
Michigan which may allow for a period of Small Craft thresholds
over the area. This will be due to lower pressure beginning to
impinge on the high pressure that will increase the pressure
gradient over the northern portions of the lake. Small Craft
Advisory in effect for much of the nearshore and bay waters due
to winds up to 25 kts and waves as high as 4 feet.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement from Friday afternoon through late
     Friday night for WIZ022.
MARINE...Small Craft Advisory from 4 PM Friday to 4 AM CDT Saturday for
     LMZ521-541.
     Small Craft Advisory from 4 PM to 10 PM CDT Friday for LMZ542-
     543.

&&

$$

DISCUSSION...
AVIATION...
MARINE...

NWS GRB Office Area Forecast Discussion