Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 141150
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
550 AM CST Sun Jan 14 2018

Updated aviation portion for 12Z TAF issuance

.SHORT TERM...Today...Tonight...and Monday
Issued at 411 AM CST Sun Jan 14 2018

There are many forecast concerns, including cold temperatures this
morning, snow trends and amounts, possible heavy lake-effect snow
on the Lake Michigan shoreline, and winter weather headlines.

Mostly clear skies and light winds have allowed temperatures to
plummet into the teens and 20s below zero across north central and
central WI. Will continue to highlight the frigid temperatures and
a brief period of advisory criteria wind chills with a Special
Weather Statement this morning.

Snow is expected to arrive in our western counties during the late
afternoon, and eastern counties in the evening, as WAA increases
ahead of clipper low pressure system. The snow will continue
across the region tonight into Monday as an upper level low and
short-wave energy move through, and the clipper low and
associated inverted surface trough linger. Lift will be quite
strong within the Dendritic Growth Zone on Monday, so snow may be
moderate in intensity at times. Although QPF amounts are not
especially high through the period, snowfall to water ratios of
20-25:1 will support widespread snow totals of 4 to 6 inches over
most of the forecast area through Monday evening. Have issued
winter weather advisories for all of the forecast area, except
along the Lake Michigan shoreline. The advisories will start in
the early to mid evening, and go until midnight Monday night.

Models are in good agreement that a well-defined north to south
oriented LES band will move onshore over northern Door county
this evening, and intensify as it shifts farther east into the
county overnight. Heavy snow appears likely with this band, with
accumulations of 4 to 8 inches possible across Door county
tonight. With winds steadily backing from southeast to northeast
during the day on Monday, the band is expected to gradually lose
definition as it pushes west, then southwest. Regardless, there
should still be enhancement occurring along the entire lakeshore
during the day, leading to higher totals there. The current
forecast calls for 7 to 10 inches in Kewaunee and Manitowoc
counties, and 8 to 13 inches over Door county, so Winter Storm
Warnings will be issued along the lakeshore. The warning will
start mid-evening tonight, and continue through Monday night.

Used a blend of the better performing guidance sets for
temperatures, which will start off much below normal today,
then moderate to near normal tonight into Monday.

.LONG TERM...Monday Night Through Saturday
Issued at 411 AM CST Sun Jan 14 2018

Main concern for this period will be the chances for snow and
snowfall amounts Monday night with lingering chances of light
snow into Tuesday morning, very cold conditions Tuesday night
and then a gradual warming trend later in the upcoming work week
and into next weekend.

For Monday night, persistent easterly flow is expected to continue
during the evening hours. The NAM12 is suggesting that another
lake effect snow band could move into Door county during the
evening hours and then shift south across Kewaunee and Manitowoc
counties after midnight. Have increased snow chances and snow
amounts across the northeast Wisconsin Monday evening, and then
along the lakeshore after midnight. If an organized snow band does
set up, amounts near the Lake Michigan shoreline may need to be
increased.

On Tuesday, scattered lake effect snow showers or flurries will
continue across the far north. With a cold northerly flow off of
Lake Superior, believe there will be scattered light snow showers
or flurries across northeast Wisconsin before drier air works into
the area Tuesday afternoon.

Another very cold day is expected on Wednesday. Milder air will
return on Thursday with highs in the 20s. Even warmer air is
expected on Friday into next weekend. Next chance for precipitation
will occur next weekend. Based on the pattern and temperatures at
the surface/aloft, precipitation type issues are of concern. Plenty
of time to sort out the details as we approach next weekend.
&&

.AVIATION...for 12Z TAF Issuance
Issued at 542 AM CST Sun Jan 14 2018

VFR conditions will persist until mid-afternoon, with conditions
deteriorating from west to east as snow moves into the area during
the late afternoon and evening. Flight conditions will settle
into the IFR category at most locations after the steady snow
arrives, though LIFR vsbys may accompany pockets of moderate snow
late tonight, especially along the lakeshore, and in association
with a potent upper level disturbance.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 6 PM this evening to midnight CST
Monday night for WIZ005-010-011-018>020-030-031-035>038-045-048.

Winter Weather Advisory from 8 PM this evening to midnight CST
Monday night for WIZ012-013-021-039-049-073-074.

Winter Storm Warning from 8 PM this evening to 6 AM CST Tuesday
for WIZ022-040-050.
&&

$$

SHORT TERM.....Kieckbusch
LONG TERM......Eckberg
AVIATION.......Kieckbusch



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