Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 122323
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
523 PM CST Thu Jan 12 2017

Updated aviation portion for 00Z TAF issuance

.SHORT TERM...Tonight and Friday
Issued at 229 PM CST Thu Jan 12 2017

Mid level clouds associated with the departing frontal system
hanging around a bit longer over east central Wisconsin this
afternoon. Otherwise, the focus of this forecast centers on the
arctic surge of air through tonight.

Deep short wave trough with surface low will slide over the
northern Great Lakes region through tonight. Increasing surface
pressure gradient this afternoon into this evening already
producing gusty southwest winds over the northwest half of the
state this afternoon. Winds will turn west to northwest through
this evening before diminishing overnight.

Considered a headline for the afternoon and evening commute with
the increasing winds and potential of blowing and drifting snow.
Input from NWS offices to the west suggests mainly open areas
impacted. Noted some of the observations at airports across North
Central Wisconsin were observing reduced visibilities but
verification with web cams indicated good visibility. Will
continue to highlight the concern with a follow up SPS.

After coordination with area offices, will issue a wind chill
advisory for north central Wisconsin tonight with WC values near
30 below, even though values may be more temperature driven vs
wind driven. Will highlight in the SPS for the rest of the area.

After a cold sunny start Friday, mid level clouds will be on the
increase from southwest to northeast in the afternoon as a weak
upper system tracks toward the state in the RRQ region of the
upper jet. Primary weather concerns of mixed type pcpn remains well
south of the area near the arctic cold front extending from the
Central Plains to the Ohio Valley region.

.LONG TERM...Friday Night Through Thursday
Issued at 229 PM CST Thu Jan 12 2017

Forecast concerns revolve around an upper low impacting the region
early next week.  Models are in relatively good agreement for this
system, but have a slight preference for the ecmwf because
of consistency.

Friday night through Sunday...Fairly quiet with arctic high pressure
centered across the region for much of this period.  A weak
shortwave remains projected to move across the region on Friday
night, bringing broken to overcast conditions over central and east-
central WI.  Since the shortwave will be moving over top of a strong
and dry arctic high, sufficient saturation for light snow will be
rather difficult to achieve, and think the gfs looks overdone with
qpf.  Regardless, tough to rule out flurries or light snow that
could lead to a dusting.  Will keep a chance in the forecast.  This
shortwave will pull out late Friday night or early Saturday morning,
which should lead to mostly clear conditions for the rest of the
weekend.  Temps on Saturday night have potential to be much colder
than forecast over north-central WI due to clear skies and light
winds.  Will trend towards the colder mos guidance.  Temps on Sat
and Sun should be at or slightly below normal.

Rest of the forecast...As an upper level low lifts northeast across
the Plains, will see clouds on the increase late Sunday night, with
the first push of deeper moisture arriving by Monday morning over
central and east-central WI.  This first wave of precip will
continue to lift north on Monday afternoon.  Since the warm layer
aloft is anticipated to become above freezing by this time and the
ground will be cold, potential will be there for sleet and freezing
rain, especially once the sun sets.  Though breaks in the precip
will likely occur on Monday night, the threat of light mixed precip
will continue as surface temps struggle to rise much above freezing.
A secondary push of precipitation is then anticipated to arrive on
Tuesday and focus for freezing rain will likely shift to north-
central WI, since temps over northeast WI will likely rise into the
middle 30s.  Precip will finally come to an end on Tuesday night,
then a couple days of quiet and mild conditions will follow.
&&

.AVIATION...for 00Z TAF Issuance
Issued at 519 PM CST Thu Jan 12 2017

Aside from spotty MVFR vsbys in blowing snow due to gusty west
winds this evening, VFR conditions are expected to prevail through
the TAF period. A gradual increase in high clouds is anticipated
tonight into Friday, with a mid-level cloud deck arriving late in
the afternoon.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Wind Chill Advisory from 10 PM this evening to 10 AM CST Friday
for WIZ005-010>012-018-019.
&&

$$

SHORT TERM.....TDH
LONG TERM......MPC
AVIATION.......Kieckbusch



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