NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 231102
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
602 AM CDT Thu Apr 23 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- There is a marginal risk for severe weather this evening across
  the region. The best chance will be across central and north-
  central Wisconsin where strong wind gusts are possible.

- Rain and thunderstorms are expected tonight and Friday. Heavy
  rainfall may accompany any thunderstorms with a 30-55% chance
  of exceeding 1 inch of rain.

- Another round of rain and thunderstorms is forecast late Sunday
  into early Tuesday. Heavy rainfall is also possible with this
  system, with a 30-55% chance of exceeding 1 inch of rain.

- Several rounds of rain are expected to cause area rivers to rise
  this weekend into next week.

&&

.DISCUSSION...
Issued at 109 AM CDT Thu Apr 23 2026

Increasing clouds and strong warm air advection are expected today
ahead of an approaching low pressure system developing near the
international border. The strong warm air advection will allow
temperatures to soar to around 80 degrees across central and
north-central Wisconsin this afternoon, 50s and 60s near the
cooler lake. Increasing moisture will mean higher relative
humidities than previous days as dew points rise into 50s.

Showers and thunderstorms then arrive this evening, earlier than
previous runs. The earlier arrival means a higher severe weather
threat as the storms move through when MUCAPEs are a more
respectful 1000-1500 J/kg with around 20 knots of effective shear.
Although CAPE profiles are long and skinny, there is an inverted-V
look to the soundings in the lowest levels with 45-50 knots of
wind at the top of this layer. This could bring strong to severe
wind gusts to the surface with any stronger thunderstorms. The
best chance would be early this evening across central and north-
central Wisconsin closest to the maximum instability.

Showers and thunderstorms will continue the rest of tonight into
Friday as the cold front slowly moves through the region. The
long skinny CAPE profiles and PWATs of 1.2 to 1.4 inches could
bring locally heavy rainfall at times. NBM probabilities for more
than 1 inch of rain is a solid 30-55%, with a 10-20% chance of 2
inches or more of rain. The best chance for the heaviest rain is
the Highway 29 and 10 corridor, which is the area already hit from
previous rounds of rain and would exacerbate ongoing flooding.

After a period of dry weather this weekend, another system takes
aim for the area Monday and Tuesday. Early indications are MUCAPEs
are fairly low, less than 500 J/kg, with severe weather not
expected to be the primary threat. However, this system will also
have decent PWATs of 1 to 1.2 inches along with a dynamic slow
moving low pressure system. NBM probabilities of exceeding 1 inch
with this system are also 30-55%, with a 10-25% of exceeding 2
inches. These probabilities have inched upwards from the previous
run and are centered on the same area as the first system.

If both of these systems pan out on the high side of precipitation
amounts, many area rivers would climb back up to moderate or even
major flood stage by the middle of next week as evidenced by the
HEFS graphics.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 602 AM CDT Thu Apr 23 2026

High clouds will continue streaming in across the region early in
the TAF period. A small patch of low clouds (MVFR) will track
through the central Wisconsin TAF sites early in the period.
Daytime heating should cause this area of clouds to dissipate
shortly after sunrise. There is a small chance of showers or a
thunderstorm at the western TAF sites toward 00z/Fri, with more
numerous showers and embedded thunderstorms arriving in the mid to
late evening and continuing overnight. Conditions will lower to
MVFR/IFR with any showers and thunderstorms.

Light to moderate southeast winds this morning will become
stronger from the south today. Gusts to 25 to 30 kts are
possible, especially over north-central and central Wisconsin.
LLWS across the central and north-central Wisconsin TAF sites will
subside later this morning by 15Z.

&&

.HYDROLOGY...
Issued at 109 AM CDT Thu Apr 23 2026

Minor to moderate flooding continues on many rivers. Area rivers
have fallen due to the recent dry weather; however, additional
showers and thunderstorms tonight and Friday and again Monday and
Tuesday will likely lead to rivers rising again this weekend into
next week. The Menominee River could once again rise to major
flood stage around the middle of next week depending on how much
rain falls.

Those living near rivers should continue to monitor the latest
Flood Warnings and statements from the National Weather Service
in Green Bay.

&&

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

&&

$$

DISCUSSION.....Kurimski
AVIATION.......Kurimski
HYDROLOGY......Kurimski