Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 180847
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
247 AM CST Mon Feb 18 2019

Forecast discussion for routine morning forecast issuance

.SHORT TERM...Today...Tonight...and Tuesday
Issued at 247 AM CST Mon Feb 18 2019

Light snow and flurries continue across portions of east-central
Wisconsin this morning. The heaviest snow is currently from
Kewaunee south to Manitowoc where Lake Effect Snow from Lake
Michigan is currently ongoing across that region. The LES bands
should push offshore during the morning hours as winds back to the
north then north- northeast near the lakeshore. The current LES
bands appear diffuse without much organization, therefore
additional accumulations should be light, with up to an inch
possible near the lakeshore.

Once the snow comes to an end this morning, high pressure will
build in across the western Great Lakes later this afternoon and
keep the weather dry across the region through Tuesday. The high
will clear out the clouds across the area and bring colder
temperatures back to northeast Wisconsin. Temperatures today will
only rise into the middle to upper teens across north-central
Wisconsin, with highs around 20 across the rest of the area. Lows
tonight will plummet into the single digits below zero across
central and north-central Wisconsin, with a few locations probably
reaching the double digits below zero. Further east, lows will
settle to around zero degrees across northeast and east-central
Wisconsin. By Tuesday highs will recover a bit to the upper teens
to low 20s.

.LONG TERM...Tuesday Night Through Sunday
Issued at 247 AM CST Mon Feb 18 2019

Models remain consistent in holding upper ridging over the
eastern Pacific, positive-tilted upper trough from central Canada
to the southwest CONUS and a subtropical upper high over the
western Atlantic into next weekend before the Pacific ridge breaks
down and the upper trough gets shunted northeast across the
CONUS. Two systems of interest to bring precipitation chances to
northeast WI. The first system to arrive Tuesday night as a strong
piece of energy ejects out of the upper trough into the Great
Lakes with snow expected into Wednesday evening. The second system
to be the main upper trough that will arrive next weekend, but
has major timing/track issues among the models. Temperatures to be
close to normal mid-week, then warm above normal thereafter.

A prominent shortwave trough is forecast to eject northeast out
of the southwest CONUS upper trough and move into the central
Plains Tuesday night. Gulf moisture is expected to be pulled
northward and overrun an occluded surface boundary situated over
the mid-MS Valley. Furthermore, mid-level Q-G forcing will be
increasing toward WI after midnight, along with additional lift
from a coupled upper jet structure. Anticipate clouds to thicken
during the evening hours with snow chances increasing from
southwest to northeast overnight. In fact, parts of central WI
could already have an inch of new snow on the ground by daybreak.
Min temperatures to be 5 to 10 above zero north, middle teens far
south.

Both the shortwave trough and associated surface low/occluded
front lift northeast into the western Great Lakes on Wednesday
with snow over all of northeast WI. The strongest lift and
forcing to be over central and east-central WI during the morning
hours and across northern WI during the afternoon hours. Roughly
2 to 4 inches of snow is expected across the area during the
daylight hours. Max temperatures on Wednesday to be in the lower
to middle 20s north, middle to upper 20s south.

Light snow is forecast to carry over into Wednesday evening as
the system to be in the process of exiting the region. There
could also be a little freezing drizzle mixed in the with the
snow as forecast soundings show a gradual loss of ice nucleation
in the clouds. Additional accumulations of one-half to 2 inches
would bring totals into the 3 to 6 inch range and the eventual
need for an advisory. There is still time for the models to
adjust QPF amounts, thus will not issue a headline just yet. The
rest of Wednesday night to see plenty of clouds with min
temperatures from 10 to 15 above north, 15 to 20 degrees south.
High pressure is forecast to stretch from the northern Plains
through the Midwest on Thursday and bring back some sunshine to
the region, especially by the afternoon hours. A southwest flow
aloft will also allow temperatures to warm a bit with readings in
the middle to upper 20s central WI, upper 20s to lower 30s
eastern WI.

This surface high will gradually move to our east by Friday, but
remain the main weather feature for northeast WI, although clouds
are expected to be on the increase Friday afternoon as the main
upper trough begins to shift east into the Rockies. Max
temperatures to generally be in the upper 20s to lower 30s.

The forecast becomes more uncertain starting Friday night as
pieces of shortwave energy eject northeast out of the upper
trough and could impact northeast WI. There will also be some jet
help with a right entrance region for lift Friday night into
Saturday. Have included medium to high chance pops during this
time with temperatures warm enough to allow for rain/snow mix
across east- central WI Saturday afternoon. Models continue to
waffle with the timing/movement of the upper trough and
track/strength of the associated surface low into the Great Lakes
Saturday night into Sunday. Until there is better agreement, have
used the consensus solution which shows high chance or likely
pops across northeast WI. Precipitation type could also be an
issue depending on the storm track, thus anyone with travel plans
next weekend will want to watch later forecasts in the coming
days. Temperatures should remain above normal next weekend.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 1142 PM CST Sun Feb 17 2019

Northeast flow off Lake Michigan will continue to produce lake-
effect snow over the lakeshore counties overnight, with the more
significant snow gradually shifting south through the night.
Although a lull in the snow was occurring at MTW at TAF issuance,
a decent snow band appears poised to move through between 07z-
10z/Monday, followed by a decreasing trend toward daybreak. IFR
conditions are anticipated during this period of more significant
snow.

Elsewhere, areas of MVFR ceilings and flurries were observed,
especially across north central and far northeast WI. These lower
ceilings should tend to break up before daybreak, with clearing
skies occurring regionwide Monday morning.
&&

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

$$

SHORT TERM.....Kurimski
LONG TERM......Kallas
AVIATION.......Kieckbusch


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