640 
FXUS63 KGRB 111741
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1141 AM CST Thu Mar 11 2021

New Information added to update section

.UPDATE...
Issued at 1140 AM CST Thu Mar 11 2021

We continued the wind advisory in the Fox Valley and area west of
the Bay through 3 o'clock. 

&&

.SHORT TERM...Today...Tonight...and Friday
Issued at 402 AM CST Thu Mar 11 2021

Deep low pressure was moving through the Upper Peninsula of 
Michigan early this morning. A strong cold front was sweeping 
through eastern WI, and bringing widespread wind gusts to 35 to 
50 mph over the entire CWA. Some wrap-around rain showers were 
occurring over north central WI, but a wintry mix or snow was seen
in the colder air over far northwest WI. Clearing had arrived in 
parts of eastern WI, but low clouds were in place west of the Fox 
Valley and lakeshore areas.

Although the highest wind gusts (to around 50 mph) will likely 
occur over eastern WI over the next few hours (in association 
with the strongest CAA), gusts to 35 to 45 mph will persist over 
much of the region through early to mid afternoon. Have expanded 
the Wind Advisory north to the Michigan border, and extended the 
timing until 21z for the lakeshore counties. Have also extended 
our Gale Warning to 21z. The winds will drop off quickly in the 
late afternoon.

Wrap-around precipitation will impact far north central WI this
morning, with light rain changing to light freezing rain or snow
before ending. After a cloudy start to the day, skies will clear
in the afternoon. Highs will range from the upper 30s far north
to the 40s elsewhere.

A short-wave trough and associated secondary cold front will
impact the region tonight, bringing colder temperatures and a small
chance of snow showers to the far north. Lows should range from 
the middle teens far northwest to around 30 southeast.

Canadian high pressure will bring plenty of sunshine on Friday,
along with highs in the 30s and lower 40s.

.LONG TERM...Friday Night Through Wednesday
Issued at 402 AM CST Thu Mar 11 2021

Split flow regime expected across the CONUS this weekend with the
main player being a southern stream closed upper low that is
forecast to move across the Rockies. Models indicate this upper
low will move across the central Plains toward southern sections
of the Great Lakes and weaken a bit in the process. Models are in
disagreement on how much of an impact this system will have over
northeast WI. Some models then show a second closed upper low that
would move into the central/southern Plains mid-week, but there
are serious model issues, so confidence is rather low after
Monday. Temperatures for the most part will be slightly above
normal through the period.

High pressure to be parked over the Great Lakes region Friday
night, bringing mainly clear skies and light winds. Near ideal
radiational cooling conditions will allow min temperatures to fall
into the upper single digits to lower teens far north, upper teens
to lower 20s south. This high pressure to slowly drift to the
south on Saturday, but remain in firm control of our weather.
Under mostly sunny skies and a west-southwest wind at 10 to 15
mph, look for max temperatures to range from the lower to middle
40s near Lake MI, upper 40s to lower 50s inland.

A secondary area of high pressure located over northeast Manitoba/
west-central Ontario will continue to feed dry air into WI
Saturday night. Winds will gradually veer north-northeast
overnight and should prevent any clouds from reaching the area as
the first closed upper low moves into the central High Plains. Min
temperatures to be in the lower to middle 20s north, upper 20s to
around 30 degrees south. The closed upper low slowly moves east
into the central Plains on Sunday, while northeast WI remains on
the southern edge of the Canadian high pressure. Still think
models may be too quick with the increase in clouds into central/
east-central WI. Anticipate partly cloudy skies at worst with
mostly sunny skies north. Max temperatures on Sunday to range from
the middle 30s to lower 40s near Lake MI, to the upper 40s west of
the Fox Valley.

As the upper low tracks east across the central Plains toward the
mid-MS Valley Sunday night into Monday, models weaken the low a
bit. Meanwhile, the high pressure is expected to build southeast
toward the eastern Great Lakes. Expect to see some increase in
clouds Sunday night, but no precipitation just yet. The ECMWF has
changed its tune now for Monday, by bringing a frontogenetically-
forced band of precipitation into northeast WI. The bulk of the
precipitation would occur in the afternoon, thus allowing for
precipitation type to mainly be rain. The GFS keeps the bulk of
the precipitation to our south. Have kept pops in the chance
category for now, but if the ECMWF verifies, pops would need to be
raised. Max temperatures to be in the middle 30s to lower 40s.

Precipitation chances would continue into Monday night as the
system moves into the southern Great Lakes/north of the OH Valley.
Any rain would mix with and eventually change to light snow Monday
evening as temperatures cool. Any snow accumulation would be minor
as better lift/forcing to have shifted east by the time the snow
would start. The rest of the forecast for Tuesday into Wednesday
have some serious model issues as the GFS is focusing on another
closed upper low that would start to lift northeast toward the
Great Lakes on Wednesday. On the other hand, the ECMWF is focusing
on a northern stream shortwave trough/pair of cold fronts Tuesday
into Wednesday with no closed upper low approaching. For now, have
kept pops very low due to the high-level of uncertainty. Max
temperatures for both Tuesday and Wednesday should be around 5
degrees above normal for mid-March.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1135 AM CST Thu Mar 11 2021

MVFR ceilings should dissipate this afternoon, with 
clearing skies and diminishing winds by early evening. 

An upper trough could produce a period of MVFR ceilings and snow 
flurries late tonight north of a RHI to IMT line, otherwise VFR
conditions are anticipated across the region tonight. 

Good flying weather is expected Friday through Saturday with clear
skies and excellent visibility.
&&

.HYDROLOGY...
Issued at 402 AM CST Thu Mar 11 2021

Minor river rises have already been observed and the combination 
of melting snowpack, above normal river flow (seasonal), and 
frozen soils may lead to higher flows and possibly minor flooding 
in low-lying areas, along with area streams and rivers in central 
WI and the Northwoods and for locations downstream of those areas 
such as along the Wisconsin River, Popple River and Peshtigo 
River. 

Many rivers will continue to slowly rise through the weekend as
runoff and snowmelt continues, especially across central and
northern WI. We could see some rivers approach flood stage, but 
no major flooding is expected as the basins/reservoirs still have 
quite a bit of space to accommodate the snowmelt. The recent rain
and runoff into the streams, along with above freezing temps, 
will cause the rivers to continue to break up, which may result in
an increased threat of ice jams.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 3 PM CST this afternoon for WIZ012-013-021-
022-038>040-048>050-073-074.
&&

$$

UPDATE.........RDM
SHORT TERM.....Kieckbusch
LONG TERM......Kallas
AVIATION.......RDM
HYDROLOGY......Kallas