Forecast Discussion for GRB NWS Office
FXUS63 KGRB 021200

Area Forecast Discussion
National Weather Service Green Bay WI
600 AM CST Fri Dec 2 2022

Updated aviation portion for 12Z TAF issuance

.SHORT TERM...Today...Tonight...and Saturday
Issued at 354 AM CST Fri Dec 2 2022

Precipitation trends and snowfall amounts tonight, and strong
post-frontal winds from late this evening through Saturday
morning, are the main forecast concerns.

Expect a mild day today, as south winds and sunshine through
midday boost temperatures into the upper 30s to middle 40s.
Clouds will increase as cold front approaches the forecast area
this afternoon, but deeper saturation and precipitation looks
like it will hold off until evening.

A deepening low pressure system will move from western Lake
Superior to Hudson Bay tonight, and cause a strong cold front to
sweep across the region this evening. Forcing associated with the
cold front, a short-wave trough, and LFQ of an upper jet will
combine to produce a brief period of precipitation tonight,
especially between 03z-09z/Sat. Light rain will mix with then
change to snow as colder air surges across the region this
evening and into the early overnight hours. Accumulations of an
inch or two are still expected over Vilas County, with only a
dusting to a half inch elsewhere. West winds will crank up in the
wake of the cold front as CAA creates steep low-level lapse rates
and promotes mixing of strong winds aloft (40-45 knots in the
925-850 mb layer) to the surface. Should see gusts to 35 to 45
mph, strongest in the southern and eastern parts of the forecast
area. Although we may see a stray gust to 45 mph, have opted to
hold off on any wind headlines, and just highlight in the
Hazardous Weather Outlook. Lows tonight should reach the single
digits west to the teens and lower 20s east. Wind chills will drop
below zero across north central and central WI late tonight into
Saturday morning.

A cold and blustery day is on tap for Saturday, with highs only
reaching the teens to middle 20s. Any lingering flurries or light
snow showers (north) should taper off in the morning, followed by
plenty of sunshine. Strong west winds gusting to 30 to 40 mph will
subside in the afternoon as the pressure gradient weakens with
the arrival of a ridge of high pressure.

.LONG TERM...Saturday Night Through Thursday
Issued at 354 AM CST Fri Dec 2 2022

The upper pattern will be dominated by a broad trough and Canadian
low pressure system, which will bring several weak and fast moving
rounds of light precipitation through the region in the extended

Saturday night through Sunday... Winds will continue to abate
Saturday evening from the strong gusts Saturday morning with only
a chance gust around 20 mph overnight. Winds will also briefly
turn south to southwesterly overnight into Sunday morning, which
will bring a push of warmer air into the region for Sunday. The
warmer temperatures will bring some better mixing, bringing back
isolated wind gusts up to 30 mph for the afternoon. Highs on
Sunday will range from the middle 20s in the north to the middle
30s across the Fox Valley and sunny skies.

Rest of the forecast... The next shortwave will arrive on Monday,
quickly passing over the region through the afternoon. Moisture
will be fairly limited for this round, but there could be a brief
wintry mix across portions of central WI with any precipitation.
That said, qpf will likely be too low to prove a widespread hazard
to the region. The forecast becomes uncertain from Monday
forward as extended forecast models develop a surface low over
the southern plains and bring it north towards the Ohio River
Valley. If this system develops a bit further northwards, our next
round of precipitation could be Tuesday night on the northwestern
edge of the system to our south. On the other hand, if this
southern stream system misses instead, it would allow for the
next shortwave to arrive on Wednesday. In either case, qpf will be
fairly light as much like the Monday system, these systems will
be fairly fast moving. Thus, kept low pops in for next week, but
expect most locations to see far more dry conditions than wet
ones. Temperatures will see a dip towards the 20s and teens in the
north behind the Monday system before recovering back towards the
20s and 30s by the end of the week.

.AVIATION...for 12Z TAF Issuance
Issued at 549 AM CST Fri Dec 2 2022

VFR conditions are expected through most of today, but MVFR
ceilings are expected to quickly overspread the region in the late
afternoon and early evening. A strong cold front will bring a mix
of rain/snow this evening, which will change to snow as colder
air pushes in from the west. IFR conditions will be possible with
the precipitation in north central and parts of central WI this
evening. Accumulating snow is expected over the far north,
especially over Vilas County, where 1 to 2 inches are anticipated.

Ahead of the front, moderate south winds will prevail, along with
periods of LLWS. Strong west-northwest winds will gust to 30 to 40
kts in the wake of the cold frontal passage later this evening and
through the overnight hours.



SHORT TERM.....Kieckbusch
LONG TERM......Uhlmann

NWS GRB Office Area Forecast Discussion