NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 291728
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1228 PM CDT Wed Apr 29 2026

Updated aviation portion for 18Z TAF issuance

.UPDATE...
Issued at 855 AM CDT Wed Apr 29 2026

Updated to increase pops for the rest of today into this evening.
One short-wave is moving through east central WI now, and another
is approaching from MN. There could be a brief beak or lull in
the shower activity in between the two systems, but showers will
be numerous for the rest of the morning, and again mid-afternoon
to early evening (especially in eastern WI).

Also increased pops for the late morning and afternoon on
Thursday, and suspect lower end pops will need to be added on
Friday too.

&&

.KEY MESSAGES...

- Chance (25 to 50%) of showers today and Thursday, with rainfall
  totals generally under a quarter inch through the weekend.

- Minor flooding persists on the Wolf River and Winnebago system.
  Water levels should gradually recede as the week progresses due
  to a lack of significant rainfall.

- Below normal temperatures expected through the weekend.
  Frost/freeze potential toward the end of the week.

&&

.DISCUSSION...
Issued at 1117 PM CDT Tue Apr 28 2026

Radar continues to show weak returns percolating across northeast
Wisconsin early this morning, though any evidence of showers
making it to the surface remains well off to our south. Chance
showers (25 to 50%) then return later this morning into this
afternoon as shortwave energy and attendant surface wave pivot
over the Great Lakes. A rumble or two of thunder would not be out
of the question this afternoon due to meager daytime instability
(100 to 300 J/kg MUCAPE), though remains unlikely.

The remainder of the week will be characterized by afternoon
shower chances as a blocking upper low sits and spins over Quebec,
bringing a train of shortwaves to the Great Lakes within
northwest flow regime. However, QPF should easily be held down to
a quarter of an inch or less each day. No thunder is expected due
to a lack of instability. Some CAA snow flurries cannot be ruled
out Thursday afternoon as 850 mb temps drop between -4 and -8C,
though will remain unimpactful. Weak high pressure then builds in
for the weekend, before a potent cold front brings more widespread
precip chances early next week.

Temperatures... Expect temperatures to remain below normal through
the end of the week as a cold Canadian airmass streams into the
Midwest. Highs will read primarily in the 40s and 50s during this
time. Frost/freeze concerns then come into play toward the end of
the work week as lows fall into the mid 20s to mid 30s. Will
likely necessitate headlines across portions of central Wisconsin
to the lakeshore, where the growing season/greenup have begun.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1228 PM CDT Wed Apr 29 2026

A short-wave trough will bring widespread light showers to the
region this afternoon. These will gradually end from west to east
in the late afternoon and evening. MVFR and localized IFR
conditions will accompany the showers, but conditions will
gradually improve as the rain tapers off. Partial clearing is
expect tonight, but clouds will increase again late Thursday
morning as another short-wave arrives. This wave will bring
another round of scattered showers, but conditions should remain
VFR at most locations.

&&

.HYDROLOGY...
Issued at 1117 PM CDT Tue Apr 28 2026

Minor flooding remains limited to the Wolf River basin and the
Winnebago system, and is forecast to continue through the middle
to end of the week per RFC guidance. With a notable lack of
significant rainfall in the forecast, river levels should be
allowed to gradually recede through the weekend, with hydro/flooding
concerns becoming little to none by early next week. However,
those living near rivers or streams should continue to monitor the
latest river forecasts.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from midnight tonight to 8 AM CDT Thursday for
WIZ030-031-035>037-045.
&&

$$

UPDATE.........Kieckbusch
DISCUSSION.....Goodin
AVIATION.......Kieckbusch
HYDROLOGY......Goodin