NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 241158
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
658 AM CDT Sun May 24 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Intermittent chances for rain (20-40%) and thunderstorms are
  forecast through Wednesday. The risk for organized heavier rain
  or severe weather is low.

- Above normal temperatures are expected through the week, with
  80s forecast for Memorial Day, Tuesday, and Wednesday. A few
  spots may approach or reach 90 on Tuesday and Wednesday.

&&

.DISCUSSION...
Issued at 341 AM CDT Sun May 24 2026

Precipitation Chances...Isolated light rain showers were reported
early this morning in east-central and far northeast WI ahead of a
weak surface boundary located over western WI. Anticipate these
showers to exit the region east a few hours after sunrise. In the
wake of the showers, light winds and breaks in the cloud cover
allowed for patchy fog and low clouds to develop at times early this
morning as well. Based on guidance and trends, it does not appear
the fog will become widespread, but it may be dense at times. The
fog and low clouds will dissipate (fog) and exit east (low clouds) a
few hours after sunrise with the passage of the boundary, leaving
mostly sunny and dry conditions in place today.

Questions then arise with shower/storm activity late this afternoon
through tonight. There are indications of isolated shower/storm
activity developing over the Arrowhead of MN and tracking southeast
into far northern WI early this evening into late this evening on a
weak westerly LLJ and a couple hundred J/kg of MUCAPE. Meanwhile, a
southwesterly LLJ and WAA will increase across central WI during the
evening, which should also provide enough lift to produce isolated
to scattered showers/storms with MUCAPE around 700 J/kg. However,
short-range guidance and CAMs are struggling to agree on the
coverage and exact timing of this convection. For now, have low
chance PoPs (15-35%) in the forecast, but anticipate these will be
refined since this convection appears to be latching onto subtle
mesoscale features.

Forecast predictability is low for precipitation chances from Monday
through midweek with generally 20-35% chances for showers and storms
each afternoon/evening. An upper-level ridge builds over the central
CONUS by midweek with surface high pressure sliding into the area
during the second half of the week, leaving conditions dry in the
forecast.

Temperatures...Above normal temperatures are expected through this
forecast period with Monday, Tuesday, and Wednesday being the
warmest days with highs climbing into the 80s away from the
lakeshore. There are some indications from the NBM of a few spots
climbing into the 90s on Tuesday and Wednesday, but other ensemble
models are less impressed with this occurring. Despite dew points
forecast to remain at somewhat tolerable levels (upper 50s to low
60s), there is still a risk of being in the heat for a long period
of time, especially for those who are sensitive to heat.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 658 AM CDT Sun May 24 2026

IFR/MVFR conditions prevailed across the east-central WI TAF sites
this morning due to lingering fog and low stratus. Meanwhile,
clouds were beginning to lift and clear at the central and north-
central WI TAF sites. The fog will lift within the next hour or
two, while the clouds will exit by late this morning. VFR
conditions are then expected for the remainder of the TAF period.
However, a few light showers could develop/move into central and
north-central WI sometime after 06z Mon, possibly impacting the
AUW/CWA/RHI TAF sites.

West winds of 5 to 10 kts, with a few gusts to 15 kts, are
expected today, becoming south/southwest this evening. There are
also signs of a lake breeze developing in the mid-afternoon, which
may cause winds at MTW/GRB to turn southeasterly for a short
period.

&&

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

&&

$$

DISCUSSION.....Kruk
AVIATION.......Kruk