282
FXUS63 KGRB 020406
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1106 PM CDT Tue Sep 1 2026

Updated aviation portion for 06Z TAF issuance

.KEY MESSAGES...

- Scattered strong/severe storms possible late tonight into
  Wednesday morning over portions of central to east-central
  Wisconsin. Main threats with will be damaging winds and up to
  1" hail.

- Above normal temperatures and periodic rain/storm chances will
  continue into the weekend.

&&

.DISCUSSION...
Issued at 1048 AM CDT Tue Sep 1 2026

Meteorological fall is off to a warm start as early afternoon
temperatures have climbed solidly into the mid 80s, with dewpoint
readings in the low 70s in/around the Fox Valley. As such, heat
indices have risen into the upper 80s to low 90s across much of
east-central Wisconsin.

Storm chances tonight/Wednesday morning... Focus for the near-term
revolves around severe storm potential late tonight into early
Wednesday morning as shortwave energy and tandem front traverse
the Great Lakes. Storms should develop on the nose of a 40 to 45
knot LLJ over central Wisconsin between around 06 and 10Z
Wednesday, diminishing in coverage as they track further east
throughout the morning. Current thinking is that storms would
remain mostly elevated, though cannot rule out damaging wind
threat given 40+ knot wind at the top of the dry layer. Hail would
be a secondary threat given marginal lapse rates and skinny CAPE
profile. Locally heavy rain will be possible with storm activity,
though excessive rainfall potential should be held down due to
progressive storm motion. Greatest chance (40 to 50%) for
receiving 0.5" of QPF will be confined to central Wisconsin in
proximity to axis of higher PWATs.

Extended... Majority of the extended will be characterized by
periodic rain/storm chances and above normal temperatures as
warming ridge builds over the CONUS. However, storm
timing/predictability remains low thus far given the nature of the
synoptic pattern and model uncertainty surrounding retrograding
ridge. This will in turn affect potential cooldown heading into
next week, though signs point toward entering into a more
north/northwesterly flow regime.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1105 PM CDT Tue Sep 1 2026

Mid and high clouds will continue to spread across region through
the late evening hours. Isolated to scattered showers and storms
will continue to develop and move east along/near a warm front
situated across southern MN/WI, slowly working into the area
overnight, mainly after 06z. A larger, more intense complex of
showers and storms may impact the area after 08-09z, but there is
still come uncertainty on just how large/intense this area will be
or if it will track far enough north to impact the TAF sites.
Continued to use TEMPO groups to highlight the greatest threat
for storms at AUW/CWA, and switched the PROB30 groups to TEMPO
groups at GRB/ATW/MTW. Did add some gusty winds to the TEMPO
groups as 35+ kt winds will be possible if the complex holds
together, and even a weakening area of convection could still
produce some gusty winds. Used a TEMPO group for shower chances at
RHI overnight as well. The main threat from the storms will be
brief reductions in ceilings/visibilities, gusty winds and
torrential downpours. A stray shower or storm is possible late
Wednesday afternoon/evening, but chances too low to include.

Patchy ground fog will be possible overnight across far
northeast/east WI where dewpoints are the highest. Outside of
gusty winds in/near any storm (and possible wake low if a larger
complex of storms occurs), winds will remain under 10 kts.

&&

.FIRE WEATHER...
Issued at 1048 AM CDT Tue Sep 1 2026

Combination of dry air, subsidence/mixing from high pressure, and
warm temperatures may result in elevated fire weather conditions
developing over north-central Wisconsin later this afternoon. RHs
have already dipped down into the mid 30s across the sandy soil
regions in the far north, and should continue to decrease into
the low 30s and even upper 20s over the next several hours. Gusts
to 25 mph will be possible during this time. However, moisture
from prior rainfall should keep fuels from reaching critical
thresholds. Looking forward, extreme drought continues to expand
over portions of northwest Wisconsin, with little to no chances
for soaking rainfall currently in the forecast. Will continue to
monitor fire weather conditions throughout the month, especially
after we get our first frost/freeze.

&&

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

&&

$$

DISCUSSION.....Goodin
AVIATION.......Bersch
FIRE WEATHER...Goodin

NWS GRB Office Area Forecast Discussion