810
FXUS63 KGRB 040021
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
721 PM CDT Fri Apr 3 2026

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- Freezing rain and heavy rainfall are expected this evening
  through Saturday morning. Significant icing is expected across
  northern and portions of central Wisconsin.

- Flooding concerns continue through early next week due to
  recent rainfall and the additional rainfall expected this
  evening through Saturday.

&&

.DISCUSSION...
Issued at 112 PM CDT Fri Apr 3 2026

Ice Storm Through Saturday Morning:

A 1007 mb low, analyzed over eastern Kansas around midday, will
deepen as it lifts northeast towards southern Wisconsin tonight
and over the northern Great Lakes Saturday. Abundant
frontogenesis, in response to the TROWAL associated with this
system and Theta-E advection, will combine with Gulf moisture to
bring a slug of 0.6 to just over an inch of QPF to the region
through Saturday morning. Although precipitation could start out
as rain this evening, a Hudson Bay high will pump in dry air near
the surface across central and north-central Wisconsin. This will
mean precipitation will transition to freezing rain across north-
central and portions of central Wisconsin as surface temperatures
cool to the wet-bulb temperature. The freezing rain should then
transition back to rain Saturday morning from south to north as
surface temperatures slowly warm. Current NBM probabilities of
exceeding 0.25" of freezing rain are still a solid 50-80% across
the Ice Storm Warning area, with around a 10-15% chance of
exceeding 0.50" of freezing rain. Therefore, there will be no
changes to the headlines with this forecast issuance.

In addition to the ice, some modest MUCAPEs of a few hundred J/kg
could bring some elevated thunderstorms to the area at times
tonight, with the best chances across central and east- central
Wisconsin.

Rest of the Forecast:

The cold side of this departing low will bring some snow across
central and north-central Wisconsin Saturday evening; however, by
then the best moisture will be off to the east. Therefore, at most
a few tenths of an inch of snow is possible Saturday night and
mainly confined to north-central Wisconsin.

A period of dry weather is then expected behind the system on
Sunday as temperatures warm back into the 40s. A clipper system
will then impact the region Sunday night into Monday; however,
moisture will be limited so impacts from this system should be de
minimis. There will be additional low pressure systems tracking
through the area during the middle to late part of next week,
which will bring rain or a mix of rain and snow at times. At this
point it does not appear there will be a high impact winter
system affecting the region during the middle to late part of next
week as temperatures are a bit warmer.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 721 PM CDT Fri Apr 3 2026

A mix of VFR/MVFR conditions early this evening, but expect a drop
to primarily MVFR/IFR conditions over the next couple hours as
lower cigs arrive from the west. Vsbys will also drop as heavier
precipitation arrives from the W/SW. All precip is rain at the
moment, but a transition to freezing rain is expected from north
to south starting around 02Z. East-central TAF sites (KGRB, KATW,
KMTW) will stay warm enough for all rain.

Freezing rain transitions back to rain in central WI for a period
Saturday morning, followed by a rain/snow mix into Saturday
afternoon.

There is also a small chance (~20%) of thunder in central and
east-central WI this evening, but confidence at any one location
is too low to include in TAFs. Will monitor thunder in southwest
WI and updated as needed.

East winds persist this evening and overnight, then shift to the
west Saturday afternoon. Gusts of 20 to 25 knots will occur at
times.

&&

.HYDROLOGY...
Issued at 112 PM CDT Fri Apr 3 2026

The combination of Thursday`s rainfall and the progged system for
this evening-Saturday will lead to flooding concerns. Thursday`s
rainfall was greatest across most of the area, except in north-
central Wisconsin. For this evening-Saturday system, a widespread
0.75-1 inch of QPF is forecast. That being said, areas that
received heavy rainfall from Thursday will be more susceptible to
flooding in low-lying and poor drainage areas. Additionally, some
rivers have already been responding to Thursday`s rainfall: Oconto
River is in minor flood stage and the Wolf River at Shiocton will
soon be at minor flood stage, with several others at bankfull. A
few river sites are also forecast to approach/reach minor flood
stage this weekend or early next week.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Ice Storm Warning until 10 AM CDT Saturday for WIZ005-010>013-
018-019.

Ice Storm Warning until 7 AM CDT Saturday for WIZ020-021-030-031-
073.

Winter Weather Advisory until 7 AM CDT Saturday for WIZ035>037-
074.
&&

$$

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

NWS GRB Office Area Forecast Discussion