NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 250004
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
704 PM CDT Fri Apr 24 2026

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- Isolated to scattered showers with a rumble or two of thunder
  will be possible through this afternoon. Additional rainfall
  amounts will be light.

- Another round of moderate to heavy rain with embedded storms is
  forecast for Monday into Tuesday. Locally heavy rainfall
  between 1 and 2" will be possible.

- Rivers will continue to rise into next week following several
  rounds of heavy rain, which would exacerbate ongoing flooding.

&&

.DISCUSSION...
Issued at 1102 AM CDT Fri Apr 24 2026

Recent surface obs and satellite imagery show the cold front
out over Lake Michigan as of this afternoon, leaving only showery
activity over eastern Wisconsin in its wake. As such,
temperatures are slightly cooler than they were at this time
yesterday, maxing out in the upper 50s to mid 60s in/around the
Fox Valley. Temperatures should continue to warm by a couple
degrees over the course of the next couple of hours as low clouds
scatter out. Much drier air has also moved in behind the front,
with dewpoints dropping down into the 30s and 40s. Slight chance
(15 to 30%) showers will be limited mainly to areas along the
lakeshore for the remainder of the afternoon.

Rain/storm chances early next week... Another bout of moderate to
heavy rain remains on track for the Monday into Tuesday timeframe
following a brief dry spell over the weekend. Dynamics with this
system look slightly more impressive, with amplified synoptic flow
and a wide open Gulf bringing an abundance of moisture. Precip
onset should hold off until late Monday morning or even early
afternoon as a Hudson Bay high continues to stream dry air into
the region, with the majority of the QPF falling Monday afternoon
into Monday night. PWATs remain steady at a respectable 1 to 1.25"
(90th percentile relative to climo) along the front, with NBM
probabilistic guidance showing a broad 30 to 60% chance for
receiving one inch of rain. 10 to 25% signal for two inches
remains unchanged from the previous forecast cycle. Current
thinking is that severe weather potential would be rather limited
with only a narrow window of maximized instability. This being
said, would not be surprised to see a marginal risk up into our
southern tiers of counties for elevated hail given 35 to 40 knots
of deep layer shear and modest mid-level lapse rates. Regardless,
expecting at least some rumbles of thunder Monday evening into
Tuesday.

Extended... The remainder of the extended will be characterized by
a cooler and cloudier pattern as a blocking upper low sits and
spins over the Great Lakes. Several shortwaves pivoting around the
parent low may bring some showery activity throughout the week,
though QPF will remain minimal. Highs will average in the mid 50s
to low 60s. Overall, widespread rain and thunder chances look to
be absent through the majority of the week following the
Monday/Tuesday system.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 704 PM CDT Fri Apr 24 2026

The MVFR cloud deck was slow to move out of the region this
evening with the east-central WI TAF sites still under it.
Although, the central and north-central WI TAF sites have finally
cleared out. Additionally, light rain showers developed over
east-central WI early this evening, which may bring low-end MVFR
cigs and drop vsbys to 5SM at times. The shower activity should
come to an end by 03z Sat. Meanwhile, cloud trends suggest the
MVFR cloud deck to depart the east-central WI TAF sites an hour
or two after the rain showers end. However, the MVFR cigs will
likely remain at the MTW TAF site through at least Saturday
morning. Some models indicate the MVFR cigs may return at the
ATW/GRB TAF sites Saturday morning, but confidence was not high
enough to include for the 00z TAF issuance.

Late tonight, there are indications of fog developing across
north-central WI, and potentially in central WI. Have only
included a TEMPO group at RHI for the reduced vsbys at this time.
Any fog will burn off soon after sunrise Saturday morning.

The light northerly winds will subside this evening/overnight,
becoming light and variable throughout the remainder of the TAF
period.

&&

.HYDROLOGY...
Issued at 1102 AM CDT Fri Apr 24 2026

Minor flooding continues on several rivers, namely the Wolf and
Menominee. While the overall trend still shows water levels
receding due to rainfall underperforming last evening, this is
likely to change as we get another round of moderate to heavy rain
Monday into Tuesday. Per RFC forecasts and HEFS guidance, it
appears that the Menominee River could return to recent crests in
major flood stage later this week into this weekend, though there
is only a 10 to 25% chance of this occurring. However, increasing
snow melt from the Upper Peninsula would lend some confidence for
at least a return to moderate flood stage. A signal also exists
for the Wolf River to continue rising into moderate or even major
flood stage. Additionally, levels on the Lake Winnebago system
continue to rise due to inflow from the Wolf and Fox Rivers, with
minor flooding already occurring from Lake Poygan to Winnebago
and minor flooding forecast to occur through the weekend. Those
living near rivers or streams should continue to monitor the
latest Flood Warnings and statements from the National Weather
Service in Green Bay.

&&

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

&&

$$

DISCUSSION.....Goodin
AVIATION.......Kruk
HYDROLOGY......Goodin