780
FXUS63 KGRB 021927
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
227 PM CDT Thu Apr 2 2026

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Rain and freezing rain, mixed with sleet over north-central WI,
  will continue through this evening, before diminishing
  overnight. Tree damage and power outages are the main impacts
  from the freezing rain and icing thus far, with some slippery
  roads. The evening commute across northern WI will be impacted.
  Ice Storm Warnings and Winter Storm Warnings remain in effect.

- Thunderstorms are possible late this afternoon through the
  evening, especially over southern portions of Winnebago, Calumet,
  and Manitowoc counties. To the north of these areas, the risk
  for severe storms has diminished.

- Heavy rainfall, mixed precipitation, and thunderstorms are
  possible Friday night into Saturday. Wintry impacts should be focused
  over northern WI. A Winter Storm Watch has been issued.

- Flooding concerns arise this weekend into early next week
  following the passage of the two moisture rich systems.

&&

.DISCUSSION...
Issued at 226 PM CDT Thu Apr 2 2026

Freezing Rain, Ice through this evening...Rain, mixed with
freezing rain is lifting into northern WI. Earlier sleet that
was observed from Rhinelander north has recently given way to
freezing rain as 800mb warm layer spreads north. No change to
winter headlines in the north (Ice storm Warning, Winter Storm
Warnings) given the initial push of freezing rain into early this
evening, followed by secondary area of mainly freezing rain that
occurs late evening into the early overnight. Additional ice
accumulations up to 0.25 inch are expected before the freezing
rain, ice end overnight. Impacts so far with the ice accumulation
(many reports of 0.25 to 0.40 inch of ice, with isolated reports
up to 0.50 inch) have been tied to tree damage, power outages
versus icy roads. Currently nearly 50k customers remain without
power from central to northeast WI.

Severe Weather Potential Late this Afternoon and Evening...
Surface low over south-central IA is forecast to lift into the Fox
Valley to the lakeshore region late this evening. Expect a few
storms as this moves through, but the risk of severe weather will
be pinned over far southeast forecast area (Oshkosh to Manitowoc
and points south) on gradient of SBCAPE which stays mainly south
and where there is better potential for more organized line of
storms moving through. Even then, forecast soundings show sharp
inversion around 0.5-1.0 km (950-850mb) with MUCAPE up to 500j/kg
and effective shear less than 30 kts. Overll, given the lack of
sfc based instability and not as favorable setup with elevated
storms, seems greatest risk for severe (damaging wind gusts) in
our area will be if well organized line of storms can move through
and draw portion of the 50-55kt of winds aloft down to the sfc,
even as the near sfc instability is lacking. Timing looks similar
to what we have been indicating approximately 7p through Midnight.

A break late tonight through most of Friday, then attention turns
to yet another significant System late Friday through Saturday.
Similar to this system, more potentially significant freezing rain
and icing is expected, though the area most favored is displaced
farther north, into north-central and far northeast WI. System is
quicker moving, with bulk of QPF/freezing rain occurring Friday
evening into mid morning Saturday. Probabilities of seeing over
0.25 inch ice (NBM v5.0) have increased to 35-55 percent, highest
over Vilas and northern Forest into southwest Upper Michigan.
Footprint that could see a coating of ice takes up more area,
reaching into central WI into far northeast WI. Winter Storm Watch
that was issued on mid shift is centered where probabilities for
0.25 inch are highest and where WSSI-p shows good signal for at
least moderate impacts (smaller area of major impacts), so no
changes to that headline. Also, given the ongoing freeing rain,
icing with this first event, will not do any upgrading to that
watch right now.

Another break, but more of a clipper type system expected on
Monday with snow or a mix of rain/snow occurring. As of right now,
only looking at minor impacts for this system with marginal sfc
temps.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1229 PM CDT Thu Apr 2 2026

Expect prolonged period of hazardous flight conditions through
this evening as a Colorado Low brings IFR/LIFR cigs and a wintry
mix of rain, freezing rain, and sleet to the region. Significant
ice impacts are expected, especially at RHI, AUW, and CWA, where
freezing rain persists longest.

The freezing rain will continue to transition to rain at the east-
central WI TAF sites into early this afternoon, then at the central
WI TAF sites by late this afternoon. The wintry mix of freezing
rain and sleet over north-central WI (RHI) will gradually switch
to freezing rain the rest of the afternoon into this evening.
There will also be a chance of thunderstorms between 00z-04z Fri
for the east-central WI TAF sites. Based on latest model,
observation trends have only included PROB30 at MTW for now. If
thunderstorms develop, gusty winds and small hail would be the
primary hazards.

A period of LLWS is expected early this afternoon at the RHI TAF
site, then this evening at the east-central WI TAF sites this
evening as the low tracks overhead. Gusty east to northeast
surface winds of 20-25 kt will also persist at all TAF sites
through this evening.

&&

.HYDROLOGY...
Issued at 226 PM CDT Thu Apr 2 2026

The combination of today`s and Friday night-Saturday`s moisture
laden systems will lead to flooding concerns. A few river sites
are already forecast to reach near minor flood stage this weekend
into early next week. Also, with the ground now saturated, minor
flooding will be possible through the weekend in low-lying and
poor drainage areas.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 1 AM CDT Friday for WIZ005-012-013.

Winter Storm Watch from Friday evening through Saturday morning
for WIZ005-010>013-018-019.

Ice Storm Warning until 1 AM CDT Friday for WIZ010-011.

Ice Storm Warning until 4 PM CDT this afternoon for WIZ018-019.
&&

$$

DISCUSSION.....JLA
AVIATION.......JLA
HYDROLOGY......JLA

NWS GRB Office Area Forecast Discussion