Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 281742
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1242 PM CDT Sat Mar 28 2020

Updated aviation portion for 18Z TAF issuance

.SHORT TERM...Today...Tonight...and Sunday
Issued at 430 AM CDT Sat Mar 28 2020

The initial band of rain associated with a H8 warm front is
expected to continue to weaken as it shifts north. Most of this
band should dissipate or shift east of the area by daybreak, as
WAA/isentropic lift weakens. This will leave scattered light rain
showers across the region for the morning hours.

The next, and most significant surge of rain, is expected to occur
this afternoon and evening as the occluding surface low and associated
upper low move into the region. Rainfall amounts of 0.75 to 1 inch
can be expected during this period. Thunderstorms may enhance the
rainfall, especially over our southern and eastern counties. SPC
still has our southern counties in a Marginal risk of severe storms,
due to an enviroment characterized by strong shear and weak
elevated instability. Suspect the main threats will be small hail
and heavy downpours. Highs should be in the 40s.

Strong east-northeast winds will develop this afternoon and
evening, with gusts reaching 25 to 35 mph in most areas. Some of
the strongest gusts are anticipated over the bay and Door County
regions, where minor lakeshore flooding is expected to occur. The
flooding threat will be enhanced on the east side of Door County
due to high wave action (6 to 9 ft waves). Ice shoves appear
likely on the west side of the bay from Marinette to Oconto to
Suamico, and on the west shore of Lake Winnebago. A Lakeshore
Flood Advisory has been issued for the bayshore regions of
Marinette, Oconto and northern Brown counties, and for the eastern
side of Door County. Will issue a Special Weather Statement to
highlight the threat of ice shoves on Lake Winnebago.

The main surge of precipitation is expected to lift north of the
region after midnight tonight, as a dry slot punches into eastern
WI. The dry slot will shift east on Sunday morning, with light to
moderate wrap-around showers continuing through the day as the low
gradually departs. Temperatures may get just cold enough for a
mix of rain/snow to occur over our far northwest counties late in
the day, but little accumulation is expected. Lows tonight will be
in the middle 30s to lower 40s. highs on Sunday will range from
the upper 30s northwest to the 40s elsewhere.

.LONG TERM...Sunday Night Through Friday
Issued at 430 AM CDT Sat Mar 28 2020

The latest ensemble means indicate a relatively quiet pattern will
be in place across the region for the upcoming work week.  Shortwave
energy in the southern stream will be sliding across the southern
Mississippi Valley early in the week where it will reinforce a
longwave trough over the east coast.  Meanwhile, a northern stream
shortwave will try to move into the region around the next Thursday
time frame, though model spread is very high by this point. Prefer
to stick with the ensemble means from midweek onward.

Sunday night through Monday night...Low pressure will be exiting the
region on Sunday night.  Light precip will be diminishing as this
occurs, with model critical thicknesses looking cold enough for
minor snow accumulations over far northern WI.  Perhaps up to an
inch of accumulations will be possible on grassy surfaces. Northwest
winds will be peaking in the evening with gusts to around 30 mph,
before gradually subsiding overnight.  Some clouds will likely
linger over eastern WI into Monday morning, but should see clearing
through the day as high pressure builds into the area.  Once the
clouds depart, skies should remain mostly clear through Monday
night.  No significant changes to temps.

Rest of the forecast... May see some clouds return on Tuesday, but
should see high pressure remain centered over the area into Tuesday
night.  As northern stream energy approaches towards the northern
Mississippi Valley, light precip chances will begin to increase
during the later Wednesday into Thursday time period.  Unsettled
weather could linger into later stages of the next work week.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1241 PM CDT Sat Mar 28 2020

A strong area of low pressure is forecast to move from the Midwest
into Wisconsin tonight and toward the northern tip of Lower MI on
Sunday. Several rounds of rain showers are forecast over northeast
WI through Sunday afternoon, along with a few thunderstorms over
the southern half of the state late this afternoon/evening.
Flying conditions will be poor as MVFR/IFR conditions give way to
IFR/LIFR conditions this evening when the heaviest precipitation
arrives. In addition to the rain and low clouds, east-northeast
winds are expected to increase this evening ahead of the low
pressure. Have added some LLWS to the TAF sites for the evening
hours. Once the low passes Sunday morning, winds will become west-
northwest and become gusty in the afternoon. While some
improvement in visibility is anticipated on Sunday, cigs should
remain low as wrap-around moisture leads to additional rain
chances.
&&

.HYDROLOGY...
Issued at 430 AM CDT Sat Mar 28 2020

A widespread 1 to 1.5" of rainfall is expected this weekend. This
amount of rainfall, coupled with saturated soils, will lead to
additional rises on area rivers. Many rivers will remain above
bankfull, and several may reach minor flood stage.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Lakeshore Flood Advisory from 4 PM this afternoon to 5 AM CDT
Sunday for WIZ022-039-073-074.
&&

$$

SHORT TERM.....Kieckbusch
LONG TERM......MPC
AVIATION.......Kallas
HYDROLOGY......Kieckbusch


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