621
FXUS63 KGRB 061813
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
113 PM CDT Sat Jun 6 2026

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Warm moist airmass moving over Lake Michigan may bring a period
  of marine dense fog across our nearshore zones late tonight into
  Sunday morning, which could affect boaters. Patchy fog will also
  be possible over the lakeshore counties.

- Above normal temperatures persist for the next week. High
  temperatures in the 90s paired with increasing humidity will
  result in potential for moderate to major heat-related impacts.

- Next chance for widespread showers will be Monday into Tuesday.

&&

.DISCUSSION...
Issued at 112 PM CDT Sat Jun 6 2026

Dry weather and above normal temperatures are expected for the
rest of the weekend with a ridge of high pressure over the western
Great Lakes region. Afternoon cumulus clouds are expected to
dissipate this evening with the loss of daytime heating.

Fog...Hi-res models indicate the fog bank currently over Lake
Michigan will track back westward later tonight into Sunday
morning as winds turn easterly. The main concern is how far west
this fog bank makes it as there are some suggestions it could make
it as far as the bay of Green Bay and the lakeshore counties,
while other models keep it mostly along the Lake Michigan
nearshore waters. Given the higher certainty, will issue a Marine
Dense Fog Advisory for the Lake Michigan nearshore zones and hold
off for the Bay as well as hold off on a Dense Fog Advisory for
the lakeshore inland counties. Models indicate this fog bank
should push east on Sunday morning and dissipate entirely sometime
Sunday afternoon across Lake Michigan.

Temperatures...Warming trend continues for next week as heat
ridge builds and Hudson Bay high sets us up under southerly flow
regime. Result will be a prolonged stretch of 90+ degree days,
with little relief into the overnight periods. Confidence remains
high (generally 60 to 90%) for seeing highs in the low to mid 90s
Wednesday through Friday as ample moisture transport increases
dewpoints solidly into the 60s and even 70s. As such, heat indices
will largely read in the mid to upper 90s, with several readings
in excess of 100 degrees possible across portions of central
Wisconsin to the Fox Valley. Widespread major (level 3 out of 4)
risk for heat-related impacts are forecast during this period,
which would affect those without a means for cooling or hydration.
Though still too soon to say with certainty, will need to monitor
the potential for headlines as we head into early next week.

Rain chances...The next chance (60-80%) for widespread rain
arrives Monday into Tuesday as a fairly potent shortwave migrates
through prevailing southwesterly flow and up into the Midwest. Can
expect some periods of heavy rain during this time as PWATs
approach 2" (99th percentile), though any organized convection is
not anticipated given the lack of upper support. Probabilistic
guidance currently shows a decent signal (40 to 60%) for receiving
0.5" or rain over central Wisconsin through Monday night.

Accompanying the heat and humidity during the latter part of the
week will be a reservoir of instability that builds over much of
the upper Midwest. However, predictability for any rain/storm
chances remains low this far out as mid-level ridge sits right
overhead. Most of the ridge rider activity looks to stay off to
our west, so convective initiation in our neck of the woods would
likely hinge on smaller scale forcing mechanisms. This being said,
cannot rule out periodic chances for some stronger diurnal storms
given the magnitude of destabilization likely to occur during
peak heating.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1149 AM CDT Sat Jun 6 2026

FEW-SCT fair weather cumulus clouds are expected this afternoon,
with bases around 5-6k ft. These clouds will dissipate this
evening after sunset. Northwest winds of 5-10 knots, with gusts to
15 knots this afternoon will shift to the east at 5 to 10 knots
this evening. Exception will be near KMTW, where a southeast lake
breeze develops during the afternoon. East to southeast winds are
expected on Sunday 5 to 10 knots with gusts to 15 knots.

&&

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

&&

$$

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

NWS GRB Office Area Forecast Discussion