688
FXUS63 KGRB 272356
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
656 PM CDT Mon May 27 2024

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- There will be additional chances for showers and thunderstorms
  through Tuesday. Severe weather is not anticipated.

- Due to recent rainfall, a few rivers are expected to remain at
  bankfull but below flood stage.

- Areas of patchy frost are possible late Wednesday night into
  Thursday morning across far northern Wisconsin.

&&

.DISCUSSION...
Issued at 255 PM CDT Mon May 27 2024

Short Term...Tonight and Tuesday

Scattered showers and isolated thunderstorms should diminish this
evening as an upper level disturbance moves across southwest
Wisconsin. A couple storms could produce wind gusts to 35 mph and
pea size hail. Skies will remain mostly cloudy tonight with
cyclonic upper flow. Low temperatures will be close to normal.

Another shortwave will move across the region Tuesday, and produce
additional showers and thunderstorms. A few storms could produce
small hail and wind gusts to 35 mph in the afternoon. The clouds
and scattered showers will hold high temperatures around five
degrees below average.

Long Term...Tuesday Night Through Monday

Beginning of the extended sees lingering chances for light rain
and storms across the forecast area before a brief reprieve from
precip. A high amplitude blocking pattern will settle in across
the central CONUS mid-week, keeping most of the Midwest high and
dry into the weekend. Next chances for rain will then arrive late
Friday into early Saturday as return flow from departing high
pressure tracks a plume of Gulf moisture across the Mississippi
Valley. High temperatures will plateau in the mid to upper 70s
Saturday and Sunday following a gradual incline throughout the
week.

Tuesday evening through Friday... No significant changes to the
forecast regarding rain chances Tuesday afternoon and evening.
Light rain is expected to be ongoing Tuesday evening as a mid-
level shortwave continues to dig south across Wisconsin before
exiting to the south and east. Synoptic support remains
unimpressive due to the absence of any surface features, thus mid-
level forcing associated with the shortwave will be the main
driver for rain/storm chances. Some short-lived thunderstorms will
be possible during peak heating as a swath of marginal
instability and decent lapse rates extend into central Wisconsin.
The remainder of the work week then looks to be mostly dry as an
omega block builds into the central CONUS. Prevailing
south/southwesterly flow will hence act to advect warmer air up
from the south, resulting in a gradual increase in temperatures
into the weekend. This being said, areas of patchy frost across
the far north continue to be a concern late Wednesday night into
Thursday morning as light winds and windows for clearing may allow
for temperatures to drop down into the low to mid 30s.

Weekend rain chances... Models continue to disagree about timing
of precip arrival into the weekend. At a first glance, several
questions remain regarding rain amounts and convective potential,
including how quickly the profile can saturate due to the
influence of lingering dry air to the east. How progressive the
parent shortwave and attendant cold front are would also be a
determining factor in how long precip will linger into Sunday.
Will continue to monitor as we get closer to the event and
medium-range models come into play.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 639 PM CDT Mon May 27 2024

Short-wave energy and outflow boundary mergers will continue to
produce showers and a few thunderstorms across most of the
forecast area this evening, but any storms should dissipate by
sunset with the loss of daytime heating. Will only include a TEMPO
group at GRB for an hour with the current activity. The rest of
the showers should exit the region as the short-wave departs after
midnight. Another short-wave will arrive on Tuesday and bring
SCT-NMRS showers and a few storms to much of the region, with the
best chance of storms occurring over the southwest half in the
afternoon. Overall confidence in the occurrence of a storm at a
given TAF location is low, so will hold off on any additional
TEMPO groups for thunder at this time. VFR conditions will
prevail through most of the TAF period, though there may be a
period in the late morning and early afternoon, when the bases
of a developing cumulus cloud deck will be MVFR.

&&

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

&&

$$

DISCUSSION.....RDM/Goodin
AVIATION.......Kieckbusch