453
FXUS63 KGRB 242021
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
321 PM CDT Fri May 24 2024

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...


- Occasional showers and thunderstorms are expected into the
  evening hours. Some of the storms could be strong to severe this
  afternoon into this evening. Damaging winds, hail and heavy
  rain are possible.

- Memorial Day weekend starts off dry for Saturday, but rain
  chances increase by Sunday afternoon and continue into Memorial
  Day. A soaking rain could occur during this time.

- A few rivers over central and eastern Wisconsin could surpass
  minor flood stage early next week.

&&

.DISCUSSION...
Issued at 319 PM CDT Fri May 24 2024

Short Term...Tonight and Saturday

A negatively tilted upper trough and attendant surface front will
produce a broken line of thunderstorms as it moves across the
area into the evening hours. Showers and thunderstorms that moved
across the region earlier today and cloud cover have kept the
lower atmosphere stable through mid afternoon, but increasing
moisture convergence and and warm advection ahead of the front
should create enough instability to get things going by 22z or
23z. Strong winds and hail are the main threats from this system.

The activity will end by late evening, and cLearing skies and
drier air will arrive overnight. Low temperatures should be a few
degrees below normal. Saturday should be mostly sunny and a bit
breezy with seasonable temperatures. There could be a stray shower
in far northcentral Wisconsin.

Long Term...Saturday Night Through Friday

A 500mb trough will swing into the area late Saturday night into
Sunday morning, then move across the western Great Lakes Sunday
into Memorial Day. Beyond Memorial Day, ridging is expected across
the plains which will result in the western Great Lakes being in
a north/northwest flow pattern. The ridge should then shift east
into the western Great Lakes by Friday of next week. Temperatures
through the middle of next week will run at or slightly below
normal, then would likely trend warmer than normal late next week.

For Saturday night, a weak surface boundary will be lurking across
the far north. Per coordination with Marquette and Duluth, will
have a small chance of showers and thunderstorms across the far
north for a few hours into the evening. Dry conditions will
prevail overnight. The next system approaches from the south
Sunday morning. By noon, there will be chances of rain across
much of the area west of an Eagle River to Algoma line, with a
widespread rain event expected Sunday afternoon and evening.
There are some difference in the track of the low that could
impact rainfall amounts and also the possibility of some stronger
storms across eastern Wisconsin. Rainfall totals over an inch are
possible across much of the area Sunday afternoon and Sunday
night. This will cause rivers to rise again with several reaching
bankfull stage and at least a few rivers could reach flood stage
early next week.

On Memorial Day, the northwest flow pattern will result in more
convection developing during the day with a cool air aloft. Some
of these storms could produce gusty winds and possibly some small
hail. Confidence is not high enough to add to the Hazardous Weather
Outlook. The cool cyclonic flow combined with daytime heating may
trigger some more showers and perhaps a few storms on Tuesday.
Dry conditions are expected Wednesday and Thursday with the next
chance of rain on Friday. Frost may be possible across the north
Thursday morning as the latest guidance would suggest lows in the
middle to upper 30s.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1258 PM CDT Fri May 24 2024

Widely scattered showers and thunderstorms were exiting eastern
Wisconsin at 17UTC. A few showers with surface wind gusts to 30
knots are possible for the remainder of the afternoon.

A line of thunderstorms is expected to form across eastern Minnesota
and eastern Iowa later this afternoon and move across WIsconsin
this evening. A period of MVFR/IFR conditions will likely
accompany the convection.

A cold front will move through later tonight and bring clearing skies
for late tonight and Saturday.

&&

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

&&

$$

DISCUSSION.....RDM/Eckberg
AVIATION.......RDM