NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 251056
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
556 AM CDT Sat Apr 25 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

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

- Rivers are expected to rise next week after a round of moderate
  to heavy rain early in the week.

&&

.DISCUSSION...
Issued at 116 AM CDT Sat Apr 25 2026

A period of dry weather this weekend:

High pressure will bring a period of dry weather this weekend
across the western Great Lakes region. Due to less rainfall with
the previous system, area rivers are expected to continue their
downward trend or only experience a modest rise through the
weekend.

A round of moderate to heavy rain early next week:

A low pressure system emerging over the central Plains will deepen
as it tracks towards the western Great Lakes region late in the
weekend. As was mentioned yesterday, a Hudson Bay high will pump
dry air into the region ahead of the system with southeasterly
winds. This will act to delay the onset of precipitation, which is
now not expected until later in the day on Monday. Despite the
delay in precipitation onset, the system will still bring a swath
of moderate to heavy precipitation to the region as PWATs soar to
1 to 1.3 inches. NBM probabilities for rainfall have increased
this cycle with a 30 to 70% chance of more than an inch of rain
and a 10 to 35% of more than 2 inches centered on the Highway 29
and 10 corridor. The severe weather risk during this period does
not appear high as MUCAPEs are at or below 500 J/kg with very
skinny CAPE profiles and elevated instability according to model
soundings. There will be thunderstorms at times, especially
through Monday night with this system.

Another period of dry weather:

After this system clears the region, the middle to later part of
next week looks to be cooler with relatively quiet weather
expected. Some embedded shortwaves could bring a small chance
(10-20%) for light precipitation at times during this period;
however, the impact would be rather low as QPF amounts are only a
few hundredths. Despite this stretch of quiet weather, area rivers
may continue to rise during the middle to late part of next week
as precipitation works its way through the river basins.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 555 AM CDT Sat Apr 25 2026

IFR/MVFR stratus clouds are hanging tough across eastern
Wisconsin this morning and if anything have expanded to the west
overnight. Across the rest of the region fog has for the most part
failed to materialize despite light winds and mostly clear skies.
The stratus clouds are expected to slowly lift throughout the
morning as daytime heating lifts the bases of the clouds or erodes
them completely. Otherwise, high clouds will stream in from the
west as a cold front gets hung up across the upper Mississippi
Valley.

Light and variable winds are expected at most terminals
throughout the TAF period, with light northeast to east winds at
the east-central Wisconsin TAF sites this afternoon.

&&

.HYDROLOGY...
Issued at 116 AM CDT Sat Apr 25 2026

Minor flooding continues on several rivers, namely the Wolf and
Menominee. While the overall trend still shows water levels
receding or only rising modestly due to less rainfall from the
last system, 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 5 to 10% chance of this occurring,
which is down from the last guidance. However, increasing snow
melt from the Upper Peninsula would lend some confidence for at
least a return to moderate flood stage.

Due to less rainfall, the Wolf River is no longer expected to get
back to major or even moderate flood stage, even with the high end
HEFS guidance. 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.....Kurimski
AVIATION.......Kurimski
HYDROLOGY......Kurimski