NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 230654
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
154 AM CDT Tue Jun 23 2026

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Next chance for widespread showers and thunderstorms arrive
  later this evening and overnight, then continuing on Wednesday.

- Marginal Risk of severe thunderstorms on Wednesday afternoon and
  early evening, generally along or south of a line from Tomahawk
  to Sturgeon Bay.

- There is a 20-40% chance of showers and thunderstorms on
  Thursday.

- Near to below normal temperatures most of the week, then more
  summer-like conditions arrive over the weekend. Along with the
  warmth, periodic chances of thunderstorms later this weekend
  through early next week will potentially lead to an increase
  risk of severe weather.

&&

.DISCUSSION...
Issued at 154 AM CDT Tue Jun 23 2026

Another tranquil but cool morning across the region. Temperatures
over the far north were in the lower to middle 40s with upper 50s
to around 60 across central WI. Mid and high clouds were racing
eastward across the area.

For today, tranquil conditions will prevail with highs in the
middle to upper 70s. The chances of showers and thunderstorms will
be on the increase later this evening across central and north-
central WI. Still a few hours difference on the arrival time based
on the slower NAM12 and the quicker HRRR. Showers and storms will
overspread northeast WI overnight into Wednesday morning. The
first impulse should exit the area during the morning, resulting
in diminishing chances of rain for a few hours before showers and
storms get going again during the late morning and afternoon. The
latest SPC Day 2 Outlook has a Marginal Risk of severe weather
generally along or south of a line from Tomahawk to Sturgeon Bay.
MUCAPES of 500-800 J/KG and 0-6 km shear values around 30 knots
would support a few strong or severe thunderstorms Wednesday
afternoon into early Wednesday evening. PWATs are still expected
to climb to around 1.25", which will likely result in locally
heavy rain in spots. DESI indicated a 30-60% chance of 1" of rain
over much of the area, except across Door County where the
probability is less than 30%.

For Thursday, some instability showers and storms (20-40% chance)
are expected from late morning into early evening. Severe weather
is not expected.

Over the weekend into the middle of next week, the models are
showing a more typical summer time pattern with increasing heat
and the chances of thunderstorms. With a building 500mb ridge,
will need to watch for ridge riders as complex of storms will
move along the mean flow on the backside of the ridge from time to
time. The MEX guidance is considerably more bullish on the heat
for early next week compared to the ECMWF guidance. However,
thunderstorms can play havoc to high temperatures  at times
depending when the move across the area or leave outflow
boundaries that temper high temperatures.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1041 PM CDT Mon Jun 22 2026

VFR conditions are expected until late in the TAF period. Mid and
high clouds will invade the region from the west overnight before
fair weather clouds with ceilings above 5000 ft build with
heating by late morning.

Winds will be relatively light through the TAF period and under 10
kts.

Expect flight conditions to deteriorate Tuesday night as cloud
bases lower and precipitation moves in from west to east. Timing
of the showers is roughly from 03-04z at RHI, AUW, CWA and around
05-07Z at GRB, ATW, MTW. Brief visibility reductions to MVFR is
possible in the heavier showers, but will let subsequent shifts
take another look before adding.

&&

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

&&

$$

DISCUSSION.....Eckberg
AVIATION.......MPC