Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 01/06/20

Area Forecast Discussion

National Weather Service Green Bay WI

 531 PM CST Sun Jan 5 2020

Updated aviation portion for 00Z TAF issuance

.SHORT TERM...Tonight and Monday
Issued at 158 PM CST Sun Jan 5 2020

Focus in the short term is on current radar trends as a band of
snow traverses the forecast area. Snow is expected to clear the
area by this evening, and the focus shifts to increasing winds
and cloud trends through tomorrow.

Early this afternoon (20Z) main band of snow was moving through
northeast and east- central Wisconsin, while snow had come to an
end across much of central and north- central Wisconsin. As the
snow ended visibilities improved from 1-2 miles up to 5-10 miles.
Snowfall forecast generally on track, with the highest snow report
so far of 2 inches in Three Lakes, about 1.8 inches in Wausau,
and just a trace so far in Green Bay. Current radar trends
indicate the back edge of the snow band to be through Green Bay
and the Fox Valley by around 3PM, and through the lakeshore and
far northeast WI by 4PM. A few lingering flurries or
drizzle/freezing drizzle are possible for a brief period after the
main band moves through, but do not expect this to last very
long.

Main event this evening will be the increasing winds. As
surface frontal boundary moves through winds veer to the NW and
increase to around 15 to 20 mph with gusts of 25 to 35 mph
expected. This could create pockets of blowing snow in locations
that received measurable snow this afternoon, but again, do not
expect major impacts from blowing snow. Winds will make driving
high profile vehicles more challenging and could produce ice
shoves along the western shore of Door County and along the
eastern shore of Lake Winnebago. Winds will slowly start to
subside late tonight.

After several days of persistent cloud cover, confidence is fairly
high that we`ll get sunshine tomorrow. Satellite imagery shows a
large area of clearing from the Central Plains up through Alberta
Canada. Models also agree on this clearing with much dryer air
filtering in this evening. Mostly sunny skies are expected
throughout Monday, with westerly winds in the 10 to 20 mph range.
Temps to remain above normal, with morning lows ranging from the
mid to upper teens in the Northwoods, to the middle 20s along Lake
Michigan. Highs Monday generally in the lower 30s.

.LONG TERM...Monday Night Through Sunday
Issued at 158 PM CST Sun Jan 5 2020

The pattern looks to become more active during the extended period
as a series of low pressure systems track through the region. The
first of these systems will track through Monday night into
Tuesday as a low moves through southern Canada, bringing a cold
front through the western Great Lakes region on Tuesday. This
first system will be moisture starved, as it will not tap into
Gulf moisture. Therefore, POPs will stay rather low with not much
in the way of snowfall expected. The best chance for snow will be
across north-central Wisconsin closer to the moisture and dynamics
from the main low, where around an inch of snow could fall.

Behind the low the region gets a shot of cold air, as lows Tuesday
night plummet to around zero central and north-central Wisconsin.
East-central Wisconsin will be a bit milder, however lows will
still be around 10 degrees. Despite the shot of cold air,
temperatures will actually be close to normal for this time of
year.

After a brief break in the action Tuesday night and Wednesday, the
active pattern continues Wednesday night and continues through
Thursday night as a fairly potent low pressure system tracks
through the northern Great Lakes region. This system looks to tap
into Gulf moisture, which will mean a better chance of
precipitation across the region. The main question continues to be
how will the system come together. The GFS brings the system
together over the western Great Lakes region, with one quarter to
one half of an inch of QPF across northeast Wisconsin while the
ECMWF and Canadian keep the best precipitation farther east across
the central Great Lakes with up to one tenth of an inch across the
area. This is related to how strong the mid level PV anomaly is
as it tracks through the western Great Lakes with the GFS
developing a better defined trough and the ECMWF/Canadian a
flatter trough. Given the model uncertainty will maintain the
blend with this run for this period. Regardless of the outcome it
appears that precipitation type will mainly be rain across east-
central Wisconsin, snow across north- central, and a mix across
central and northeast Wisconsin. QPF amounts will largely
influence snowfall amounts, however at this point it appears
amounts could range from a few inches to several across mainly
north-central Wisconsin.

Attention then turns to a system ejecting out of the southern
Plains on Friday, tracking to the southeast of the area Friday
night into Saturday. While the GFS and Canadian keep this system
well to the southeast, the ECMWF is close enough to be a concern
as it tracks the low over the northern Ohio Valley. If this system
jogs much more to the northwest it would have an impact on east-
central Wisconsin. Beyond Saturday the models diverge
significantly with very little in the way of agreement by next
Sunday.
&&

.AVIATION...for 00Z TAF Issuance
Issued at 530 PM CST Sun Jan 5 2020

MVFR clouds will dissipate this evening, with VFR
conditions later tonight through Monday. Low level wind shear
could affect some aircraft tonight with northwest winds around
40 knots at 2000` and west surface winds of 10 to 20 knots. The
gusty west winds could produce some blowing snow on runways and
taxiways at airports that received snow this afternoon.

An upper level disturbance could bring MVFR ceilings and very
light precipitation late Monday night and early Tuesday.
&&

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

$$

SHORT TERM.....KLJ
LONG TERM......Kurimski
AVIATION.......RDM