Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 150437
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1037 PM CST Thu Dec 14 2017

Updated aviation portion for 06Z TAF issuance

.SHORT TERM...Tonight and Friday
Issued at 249 PM CST Thu Dec 14 2017

Snow shower and flurry activity a little more robust than models
were indicating across central and north central WI this
afternoon, as a weak shortwave crosses the area. Webcams not
showing much in the way of accumulation. However, untreated
roads/sidewalks could continue to have some slippery spots.

Expect the snow showers and flurries to continue and slowly spread
east through the late afternoon and evening hours as the area
remains in a cold, moist, cyclonic flow with a couple weak
shortwaves crossing the area. The area will also reside in the
left exit region of a 100+ knot jet, which will aid in overall
lift. Expect the highest totals (1-2") to be across northern WI
where snow showers will get a little boost from some enhancement
off of Lake Superior, especially late tonight and early Friday
when winds turn more NW. Under an inch is expected for locations
to the south. Plenty of clouds expected across the area tonight,
so temps won`t be able to plummet like they did last night. Lows
should fall into the upper single digits to middle teens.

Lingering snow showers are expected on Friday over far northern
WI, with just the chance of flurries across the rest of the area.
A pocket of drier air does cross the area during the morning
hours, but can`t rule out a few flurries in the pattern. The dry
air should allow for a least some partial clearing, but any
clearing will end in the afternoon as clouds increase from the
west ahead of the next system. West winds could gust up to around
25 mph in the late morning and early afternoon. It will be a
chilly day with highs only in the middle teens (north) and upper
teens to lower 20s elsewhere.

.LONG TERM...Friday Night Through Thursday
Issued at 249 PM CST Thu Dec 14 2017

Forecast concerns revolve around snow chances for Friday night and
Saturday, and also next week.  A blend of the ecmwf/gfs will work
for much of this forecast.

Friday night through Sunday...Mid-level warm advection will be
increasing over the western Great Lakes on Friday night, north of
a developing warm front. Though moisture will be in short supply
and mid-level lapse rates will be rather poor, fgen in the mid-
level baroclinic zone is decent, to go along with upper divergence
in the left front quad of a jet streak. The atmosphere may take a
little while to saturate on Friday evening, but think a band of
light snow will spread southeast into central WI by mid to late
evening and into eastern WI shortly thereafter. Models then
indicate that the snow band will gradually shift north later
Friday night into Saturday morning before a diminishing trend
takes place on Saturday afternoon. Because the band will be moving
and issues with moisture/instability, think a 1-2" snowfall is
possible over central to east-central WI, and lesser amounts
elsewhere. High pressure will then reassert itself on Saturday
night. Though partial clearing is possible, a low stratus deck
will be difficult to dislodge across the area, without an influx
of dry Canadian air. Some flurries also could occasionally occur,
especially over northern WI, through Sunday. No significant
changes to temps.

Rest of the forecast...The next shortwave trough and associated
cold front will swing through the area during the Monday
afternoon into Tuesday period. This system will bring the next
chance of widespread light snow to go along with breezy or windy
conditions. After a brief warm up on Monday, temps should slide
closer to normal on Tuesday. A more potent system could impact the
region late Wednesday into Thursday, but confidence of
track/timing is rather low.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 1036 PM CST Thu Dec 14 2017

Occasional light snow and flurries will continue across the area
the rest of tonight and into tomorrow morning. Anticipate a mix
of low-end VFR and MVFR conditions, with the poorer conditions
more prevalent across the northwest part of the forecast area.
Still not much change expected through tomorrow.
&&

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

$$

SHORT TERM.....Bersch
LONG TERM......MPC
AVIATION.......Skowronski



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