NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 231134
AFDGRB

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

Updated aviation portion for 12Z TAF 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 12Z TAF Issuance
Issued at 630 AM CDT Tue Jun 23 2026

VFR conditions expected today as a cumulus deck between
4,000-6,000 develop later this morning into the afternoon.
Showers and thunderstorms are expected to move into portions
central and north-central WI after 03z Wed. However, these
storms will not reach eastern WI until after 07z. VFR CIGS
are expected to drop into the MVFR or IFR category or lower
from west to east late tonight and Wednesday. Showers and
scattered thunderstorms will continue Wednesday into Wednesday
evening before gradually tapering off and ending. Areas of fog
are likely late Wednesday night into Thursday morning.

&&

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

&&

$$

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