Forecast Discussion for GRB NWS Office
FXUS63 KGRB 280947

Area Forecast Discussion
National Weather Service Green Bay WI
347 AM CST Sun Nov 28 2021

Forecast discussion for routine morning forecast issuance

.SHORT TERM...Today...Tonight...and Monday
Issued at 347 AM CST Sun Nov 28 2021

Main focus the next 36 hours will the lake effect snow across
north central WI and gusty winds today and another clipper system
on Monday bringing a quick shot of snow. Temps will run near or
slightly below normal.

For today...early morning satellite showing low clouds holding
tough across north central WI and Door Co., with some clearing as
you head towards/into the downslope region of central and eastern
WI. Lake effect snow activity will continue to pick up early this
morning across north central WI as colder air arrives and winds
turn to the northwest. The LES activity will continue through the
early afternoon hours, aided by a passing shortwave over the
central Great Lakes, then diminish later this afternoon as winds
turn more westerly, the shortwave exits and delta Ts fall over
western Lake Superior. Additional accumulations in far north
central WI look to be under an inch, with a locally higher amount
possible near the MI border in Vilas Co. Flurries and snow
showers will also push across northern Door Co. this morning.
Farther south/east, some lake effect clouds are expected at times
along with a few flurries, especially this morning. Northwest
winds will be gusty today as CAA continues much of the day. Winds
aloft support gusts of 25-35 mph with a few higher gusts possible
during peak mixing. Winds will diminish towards sunset. Highs will
range from the upper 20s in north central WI to the middle 30s in
the Fox Valley and lake shore.

For tonight...most of the night will quiet as weak surface high
pressure builds across the western Great Lakes. Winds will
continue to diminish in the early evening then remain light the
rest of the night, shifting to the south/southwest. The next
clipper will quickly approach from the northwest toward sunrise,
with some light snow possibly reaching central and north central
WI. Temps look to drop off into the teens and low 20s for most
spots in the evening hours, then will remain steady or slowly rise
overnight as thicker clouds arrive.

For Monday...the next in a parade of clipper systems will race
across the area during the day, with impressive FGEN/ isentropic
lift accompanying it, spreading a band of light to moderate
snowfall across much of the area. While there is better consensus
with this clipper, similar forecast concerns exist with this
clipper as with the last, including the track of the low, best
FGEN location and how much the low-level dry air will eat away at
snow totals. A warm layer around 4000-5000 ft could also throw a
minor wrench in the p-type for a period in the mid-late morning
and early afternoon. The layer looks pretty shallow and models
handle it differently, so will keep freezing rain and sleet out of
the forecast for now. Best chance for this to occur would be in
central WI, closer to the warmer air and where the QPF is
forecast to be the lowest. As the snow quickly ends in the
afternoon, a period of freezing drizzle will be possible as dry
air arrives in the mid-levels. This should occur mainly where the
snow falls, so impacts look to be low. Models have trended higher
with QPF, especially over far northeast WI, so will bump up
forecast snow amounts to around 3" near the MI border. Looks like
parts of central WI will miss out on most of the snow. South to
southwest winds will gust up to around 25 mph. We could be near
advisory criteria over far northeast WI, but with the quick
hitting nature of the system, dry air to overcome at the surface,
and high DGZ, will hold off any headline. Highs will be in the
upper 20s to middle 30s for most spots, with some warmer readings
in the upper 30s to perhaps around 40 in Wood Co.

.LONG TERM...Monday Night Through Saturday
Issued at 347 AM CST Sun Nov 28 2021

A couple opportunities for precipitation in the long term forecast
as northwest upper flow carries shortwave energy across the
western Great Lakes. This pattern will also lead to near and
slightly above normal temperatures through most of the forecast
period, turning cooler next weekend.

One clipper and associated shortwave energy will continue moving
east Monday evening. Some lingering light snow or freezing drizzle
is possible for a few hours, but most places will be dry by this
time. Quiet weather follows for Tuesday.

Models are in agreement showing another clipper impacting the
western Great Lakes on Wednesday. Track and timing differences
remain, so continue to carry chance PoPs through much of Wednesday
and Wednesday night, but not expecting a long-lasting event at
this time. Temperatures Wednesday are also forecast to rise into
the upper 30s and lower 40s. So while some snow is possible at the
onset, rain is likely to be the precip type by late Wednesday
morning into the early evening. Some light snow is possible again
Wednesday evening as the clipper pulls away.

The rest of the week should be fairly quiet with temperatures
running a few degrees above normal. Northwest winds across Lake
Superior could lead to occasional lake effect snow showers in far
north-central WI. The main time period to watch is next Sunday
and/or Monday as long range models show the potential for a more
substantial system to impact the area, but there are considerable
differences at this point with plenty of time for changes.

.AVIATION...for 06Z TAF Issuance
Issued at 1009 PM CST Sat Nov 27 2021

Light snow and patchy freezing drizzle will gradually taper off
over northern Door County overnight, but lake-effect snow showers
are expected to increase over north central WI. Expect a mix of
MVFR and VFR conditions over most of the area, with the exception
of IFR VSBYs in the lake-effect area. Partial clearing is expected
overnight into Sunday morning, with more widespread clearing
occurring as a surface ridge arrives in the late afternoon and

Northwest winds will increase and become gusty overnight into
Sunday, then diminish by sunset.



SHORT TERM.....Bersch

NWS GRB Office Area Forecast Discussion