Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 011009
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
409 AM CST Mon Mar 1 2021

Forecast discussion for routine morning forecast issuance

.SYNOPSIS...
Issued at 406 AM CST Mon Mar 1 2021

Relatively quiet weather for the first week of March, with
temperatures generally a little to modestly above seasonal
normals after today.

The upper flow across North America will be dominated by a primary
band of westerlies across the northern United States and southern
Canada. A separate, weaker southern stream will remain across the
southern CONUS and is unlikely to affect the forecast area. The
main westerlies will be progressive as they flatten the next
few days, then progression will slow as amplification occurs
during the latter part of the period.

The forecast area will remain under the influence of the primary
band of westerlies during the period. Since the area will
generally be located downstream from ridging and gulf moisture
will remain tied up to the south of the area, little if any
precipitation of consequence is expected. The period will start
with the forecast area taking a glancing blow from a bitterly
cold air mass surging southeast from Canada. Once that shifts east
of the area, temperatures will range from slightly to modestly
above normal.
&&

.SHORT TERM...Today...Tonight...and Tuesday
Issued at 406 AM CST Mon Mar 1 2021

A strong, cold anticyclone from Canada will surge southeast into
the northern Plains today. The high will bring a shot of cold air
to the area. An area of mid-level FGEN along with some upper
divergence in the LFQ of a speed max will shift through the area
early today, likely generating scattered snow showers and
flurries. Low-level trajectories will also be favorable for some
SHSN off Lake Superior to reach northern Wisconsin, and possibly
northern Door County. But the incoming air mass is dry, so
anticipate just trace amounts to perhaps up to a half inch at a
few locations in the snowbelt.

The high will quickly shift across the area this evening, then
begin departing off to the southeast overnight. Favorable
conditions for radiational cooling will be present early in the
night, but some mid-clouds will brush the north during the night
and surface winds will begin to pick up after midnight. So while
temps will probably drop off considerably during the evening
(especially across the fresh snowcover in the far north), they
will probably stabilize and rebound a little by daybreak.

Gusty southwest winds between the departing anticyclone and a
cyclone tracking across southern Canada will overspread the area
Tuesday. The depth of mixing that can be achieved will determine
the wind gusts. Stayed close to the NBM given the uncertainty in
the amount of mixing that will occur.

.LONG TERM...Tuesday Night Through Sunday
Issued at 406 AM CST Mon Mar 1 2021

A quiet period of weather expected Tuesday night through the
weekend (especially for early March standards) as split flow will
prevail over the CONUS. Still some question of how warm it will
get through the period, but temps still look to be near or above
normal.

Tuesday night...shortwave trough will track east across the
northern Great Lakes, but it looks like any measurable precip will
stay north of the area. Can`t rule out a flurry or sprinkle over
northern WI, but will keep the forecast dry. Winds will slowly
diminish during the evening hours as the pressure gradient
slackens between the exiting weak surface low to our northeast and
high pressure over the Ohio Valley. As skies clear, some patchy
fog will be possible overnight. With the WAA during the daytime,
lows will be much warmer compared to Monday night, with readings
mainly the upper teens and 20s.

Wednesday through Friday...quiet weather expected as surface high
pressure will remain in control. Models still show a weak
shortwave pushing across the area on Wednesday but with little in
the way of moisture/lift to speak of, will stick with a dry
forecast but increase cloud cover a little. Flow aloft will
become northwest late in the week as a strong ridge builds over
the Rockies. At the surface, flow will become more northerly which
will keep the more spring like temps to our south/west. But temps
still look to be near/above normal regardless.

Next weekend...the quiet weather looks to continue as upper flow
remains northwest and the ridging over the Rockies slowly pushes
east. Some question how fast this will occur and whether the large
upper low over eastern Canada will retrograde, holding up a more
significant push of warmer air into the Great Lakes. The
difference between southerly and north/northeast flow is 10-20
degrees. So the timing/location of these will ultimately
determine when the spring-like temps arrive.
&&

.AVIATION...for 12Z TAF Issuance
Issued at 406 AM CST Mon Mar 1 2021

Other than some MVFR and possibly isolated IFR conditions with
SHSN early today, generally good flight conditions are
anticipated. LLWS will begin to overspread the area from the NW
late tonight.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS.......Skowronski
SHORT TERM.....Skowronski
LONG TERM......Bersch
AVIATION.......Skowronski



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