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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS63 KGRB 062328
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
528 PM CST Sat Mar 6 2021

Updated aviation portion for 00Z TAF issuance

.SYNOPSIS...
Issued at 220 PM CST Sat Mar 6 2021

Warm for the start of the upcoming work week (at least away from
Lake Michigan). Some rain mid-week, then temperatures returning
closer to seasonal normals by next weekend.

The period begins with quite amplified upper flow across North
America. Deep troughs were off the West Coast and over eastern
Canada, bracketing a sharp ridge from the western High Plains to
western Hudson Bay. Energy ejecting out of the western trough will
flatten the mid-continent ridge early in the week, with a
subsequent piece of energy generating a cyclone on a cold front
crossing the area mid-week. The main energy from the western
trough will temporarily separate off into the Desert Southwest
before ejecting toward the area next weekend. But it is unlikely
to reach the forecast area until after the end of the forecast
period.

The initial shortwave ejecting out of the western trough will
flatten the upper flow to a more zonal nature, allowing a stronger
push of modified Pacific air to reach the area for the early to
middle part of the work week. That will result in well above
normal temperatures for the first half of the work week. Readings
will settle back closer to normal after that. The main
precipitation event will be associated with the frontal system and
cyclone crossing the region mid-week, and should result in AOA
normal amounts for the period.
&&

.SHORT TERM...Tonight and Sunday
Issued at 220 PM CST Sat Mar 6 2021

Tranquil conditions to prevail through the end of the weekend with
temperatures holding above normal. The only difference on Sunday
will be more wind.

The 19Z MSAS surface analysis showed a ridge of high pressure that
extended from central Ontario south through central WI, then
southwest into the southern Plains. After some early morning fog
far north, current visible satellite imagery indicated nary a
cloud to be found over WI. Temperatures ranged from the lower 30s
to middle 40s.

The surface ridge axis will slowly edge eastward tonight and
extend from eastern Ontario south-southwest through Lake MI to
northeast TX. Mainly clear skies and light winds will lead to
another cold night across northern WI where a deeper snowpack
still exists. Based on how far down temperatures reached this
morning, anticipate readings to be fairly similar and again drop
into the zero to 5 above range near the MI border, while only
falling to around 20 degrees over east-central WI.

As the surface ridge heads toward the eastern Great Lakes on
Sunday, the pressure gradient over WI will tighten between the
high pressure and an area of low pressure near Lake Winnipeg. The
resulting gusty southerly wind will also begin to tap warmer air
to our west with the help of a modest upper-level ridge. 8H
temperatures climb to around +4C and even with some increase in
clouds in the afternoon due to a shortwave trough moving into
western WI, look for max temperatures to range from the lower 40s
near Lake MI, to near 50 degrees west of the Fox Valley.

.LONG TERM...Sunday Night Through Saturday
Issued at 220 PM CST Sat Mar 6 2021

The main long-term forecast issues were attempting to hone-in on
temperatures early in the week, and precipitation chances mid-
week. The NBM has recently been too cool with temperatures-- both
highs and lows. So, edged readings up Monday through Wednesday,
though increasing south winds may keep readings close to the lake
quite chilly. Stayed close to NBM values after that.

The details of the precipitation that will accompany the
front/cyclone through the region mid-week remain murky. It would
be surprising if it doesn`t rain at some point. But given the
uncertainty in timing, likely PoPs seemed sufficient for now.
Given the steepening mid-level lapse rates, introduced a mention
of thunder on Wednesday into Wednesday evening--mainly across
central and east-central Wisconsin.
&&

.AVIATION...for 00Z TAF Issuance
Issued at 528 PM CST Sat Mar 6 2021

Ridge of high pressure to remain the dominant weather feature
over the Great Lakes through Sunday. VFR conditions will prevail,
although some fog development is possible across northern WI where
a decent snowpack still resides. As the ridge slides to the east
on Sunday, winds will veer to the south-southeast and increase as
the pressure gradient tightens over WI. Winds could gust over 20
knots by Sunday afternoon. The approach of a mid- level shortwave
trough late on Sunday is expected to bring an increase in clouds
to central WI. Cigs will remain VFR until Sunday evening when MVFR
cigs are forecast to overspread the area.
&&

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

$$

SYNOPSIS.......Skowronski
SHORT TERM.....Kallas
LONG TERM......Skowronski
AVIATION.......Kurimski