NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 231159
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
659 AM CDT Sat May 23 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Temperatures will warm through the holiday weekend with well
  above normal temperatures likely for much of next week.

- Intermittent chances for rain (20-40%) and storms at times are
  forecast through next week, but the risk for organized heavier
  rain or severe weather is low.

&&

.DISCUSSION...
Issued at 336 AM CDT Sat May 23 2026

Precipitation Chances...Ahead of an upper-level trough and surface
low to the west, light rain showers were lifting north over central
and north-central WI out of the mid-levels early this morning. These
showers are expected to continue lifting north while dissipating
before sunrise this morning. As the upper-level trough slowly moves
west, moisture from a southern stream system moving over Lower
MI/IN/OH looks to provide enough moisture to support very light rain
showers or sprinkles over far NE WI after sunrise through the early
afternoon. Then, as the trough moves in from the west, another weak
boundary associated with the trough will generate another broken
line of showers that will slowly move east across the region from
mid-afternoon through Sunday morning. With a couple hundred J/kg of
CAPE around during the afternoon, cannot rule out a few rumbles of
thunder, mainly in central WI.

Additional periodic chances (20-35%) for showers and storms are
possible beginning Sunday afternoon/evening through the middle of
next week. These chances appear to be diurnally driven with low-
amplitude low predictability shortwave troughs, leading to details
being too muddled to determine timing and placement at this time.
Generally, given no well defined forcing mechanisms, any
precipitation will be either isolated or scattered in coverage, with
dry conditions occurring most of the time.

Temperatures...With a trough progged to move overhead today, we'll
see one more day of below normal temperatures with highs ranging
from the low 60s in far NE WI to the upper 60s to low 70s in central
WI. However, if enough breaks in the clouds occur this afternoon for
an extended period of time, values may climb slightly higher than
currently forecast. Return flow on Sunday will allow temperatures to
warm above normal ranging from the mid 70s to low 80s. Upper-level
ridging will build over the northern CONUS into Memorial Day, and
remain in place through next week. As a result, highs will climb
well above normal, about 10-20 degrees above, from Memorial Day
through midweek next week. Generally, highs will be in the 80s (away
from the lake), but some ensembles indicate low probabilities of
climbing into the low 90s. 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 659 AM CDT Sat May 23 2026

MVFR cigs are expected to develop along the lakeshore this morning
and move onshore mainly impacting the MTW and GRB terminals, but
they may briefly reach ATW. VFR conditions under mid-level clouds
are expected to prevail elsewhere until the mid-afternoon, when
MVFR cigs arrive from the west with a broken line of showers.
Confidence is lower in how far east the showers will track, so
have not included a mention of them in the east-central WI TAF
sites at this time, but did still include MVFR cigs at these sites.
Following the showers, cigs will drop to IFR (or perhaps LIFR
briefly at RHI) after midnight through the end of the TAF period.
Patchy fog may also develop with the IFR cigs.

East to southeast winds of 5 to 10 knots are expected today,
becoming light and variable overnight.

&&

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

&&

$$

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