251 
FXUS63 KGRB 161027 AAA
AFDGRB

Area Forecast Discussion...UPDATED
National Weather Service Green Bay WI
527 AM CDT Sun Oct 16 2022

Updated to add short term portion for morning forecast issuance

.SYNOPSIS...
Issued at 524 AM CDT Sun Oct 16 2022

A significant early-season snow in the Lake Superior snowbelt 
tonight into Monday. Otherwise, scattered showers today, then 
windy and colder with scattered rain and snow showers Monday. 
Chilly conditions continuing through most of the upcoming work 
week before warmer weather returns next weekend.

A highly amplified large scale pattern with a western ridge and
Great Lakes region upper trough will remain in place through 
most of the upcoming work week. The upper pattern is then expected
to transition fairly quickly to a western trough/eastern ridge
configuration. 

Temperatures will remain below normal through most of the upcoming
work week before warming sharply to considerably above normal 
next weekend when the upper flow backs southwest. Precipitation 
across most of the area will be below normal, though near-to- 
perhaps slightly above normal amounts are possible in the Lake 
Superior snowbelt. A wetter regime for the whole area will 
probably develop just beyond the end of the period, once the SW 
flow becomes established and has time to advect gulf moisture into
the region.
&&

.SHORT TERM...Today...Tonight...and Monday
Issued at 524 AM CDT Sun Oct 16 2022

Opted to post the initial advisory/warning headlines for the
upcoming lake-effect snow event with the morning issuance. The
specific snow amounts will still need tweaking, and it remains to
be seen if the significant snow showers drive far enough inland to
warrant an expansion of the advisory another tier of counties
south and east. Later forecasts can make those adjustments if
necessary.

The lake snow setup for tonight into Monday is pretty impressive.
The BUFkit lake-effect perspective indicated lake-induced 
instability will result in ELs AOA 12K ft at KIWD from late this 
afternoon until Monday afternoon, with LI CAPEs topping out over 
800 J/kg for a few hours. The low-level wind direction will be 
favorable for getting lake bands into Vilas County through 
tonight, though the flow aloft may back a little too NE to be 
ideal on Monday. However, some snow bands should still continue to
reach Vilas county Monday, and strong winds aloft are likely to 
mix down to the surface as gusts to 35 mph. Given the anticipated 
snowfall totals, blowing and drifting snow, and this being the 
first significant winter event of the season seemed more than 
sufficient to justify going with a warning. Similar reasoning was 
used to justify the advisory for the border areas, even though 
totals are currently a little below what would normally warrant an
advisory.

Strong destabilization as the cold air flows over the warm waters
of the Bay of Green Bay will likely mix at least 40 kt gusts to
the surface, and would not be surprised to see a few gusts
approaching 50 kts over the northern part of the Door. So, posted
a Wind Advisory for the Door to match the Gale Warning for the
adjacent waters of the bay and lake.

Freezing temperatures are unlikely over the Door tonight, so
dropped the FZ.A there. Not sure if Kewaunee or Manitowoc will
freeze either (it will be close), so just left the FZ.A run there.
Overall, was looking for the simplest path forward with the Freeze
headlines as doubt there is much utility left in issuing those now
that it's mid-October and we've transitioned into an early winter
pattern.

.LONG TERM...Monday Night Through Saturday
Issued at 322 AM CDT Sun Oct 16 2022

Main forecast concerns to be timing the demise of the lake effect
snows across northern WI and how far to take temperatures up at
the end of the week.

Monday night and Tuesday...
Lake effect snow showers are expected to carry over into Monday
evening, however be in a diminishing phase as drier air begins to
advect into the region from high pressure over the central CONUS.
Look for additional accumulations over Vilas County to be under an
inch with little if any accumulation farther south or east.
Otherwise, partly to mostly cloudy skies and blustery conditions
are forecast for Monday night with min temperatures in the middle
to upper 20s central WI, upper 20s to lower 30s eastern WI.
Lingering cyclonic flow could still help to produce a few snow
showers or flurries over northern WI into Tuesday. The rest of
northeast WI should be dry with partly to mostly cloudy skies as
the ridge of high pressure edges eastward into the Upper MS
Valley. Tuesday will still be quite blustery, especially over
eastern WI where gusts to be over 30 mph. Max temperatures on
Tuesday to range from the middle to upper 30s north-central WI, 
to the middle 40s east-central WI.

Tuesday night and Wednesday...
The last of any lake effect snows should end Tuesday night as the
cyclonic flow weakens, the surface ridge slowly approaches and
wind trajectories become less favorable. Still think lake clouds
will drift into northern WI, thereby keeping skies mostly cloudy.
Areas farther south should see partly cloudy skies. In addition,
winds should finally begin to subside overnight with gusts falling
below 20 mph. Min temperatures to be in the lower to middle 20s
central WI, upper 20s to lower 30s eastern WI. The surface ridge
is forecast to weaken by the time it reaches the western Great
Lakes region on Wednesday. There could be some clouds passing
through as a northwest flow aloft persists and weak shortwaves
drop southeast within the flow. No precipitation anticipated and
with west winds bringing WAA back to WI, look for temperatures to
modify a bit. Max temperatures Wednesday to be in the upper 30s to 
lower 40s north, lower to middle 40s south.

Wednesday night and Thursday...
Models are in good agreement with the passage of a cold front late
Wednesday night. Gulf moisture is practically non-existent, thus
do not see any precipitation with this front. We should see a
modest increase in clouds with a wind shift to the west-northwest.
A rather weak surface ridge is forecast to slide into the region
on Thursday which will bring partly sunny skies to northeast WI.
Max temperatures for Thursday to be in the middle to upper 40s
north, upper 40s to lower 50s south.

Thursday night and Friday...
A return flow develops across WI Thursday night as the ridge
shifts to the east. There is some model issues with the movement
of the next cold front on Friday. The GFS/CMC both send this front
through WI, while the ECMWF essentially wipes the front out. Once
again, the atmosphere is too dry to sustain any precipitation, so
dry conditions should prevail. The issue would be on temperatures
as the GFS/CMC solution would be cooler than the ECMWF (especially
the CMC). For now, have max temperatures Friday in the lower to
middle 50s north, upper 50s to lower 60s south.

Friday night and Saturday...
Dry and mild conditions are forecast across the region going into
next weekend as a southerly flow pulls warmer air northward. Max
temperatures on Saturday to reach the upper 50s to around 60
degrees north/near Lake MI, lower to middle 60s central/east-
central WI.
&&

.AVIATION...for 12Z TAF Issuance
Issued at 524 AM CDT Sun Oct 16 2022

A mix of VFR and MVFR conditions was present across the area early
this morning. The trend should be toward mainly MVFR conditions
across the west today and tonight, with the mix of VFR and MVFR 
conditions continuing in the east. Northern Wisconsin is likely to
drop to IFR tonight as lake-effect snow showers become more
numerous.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from 7 PM this evening to 7 PM CDT Monday 
for WIZ005.

Winter Weather Advisory from 7 PM this evening to 7 PM CDT 
Monday for WIZ010-011.

Wind Advisory from 4 AM Monday to 7 PM CDT Tuesday for WIZ022.

Freeze Watch from late tonight through Monday morning for WIZ040-
050.
&&

$$

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