Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 120434

Area Forecast Discussion
National Weather Service Green Bay WI
1034 PM CST Wed Jan 11 2017

Updated aviation portion for 06Z TAF issuance

Issued at 912 PM CST Wed Jan 11 2017

The winter weather advisory has been allowed to expire, and any
lingering snow should end in Manitowoc county by 10 pm. Had
snowfall totals of 4 to 6 inches from Oshkosh to Chilton to
Manitowoc, with snowfall rates briefly exceeding 2 inches an
hour at times.

Have reworked the pops for late tonight into Thursday morning
to account for another possible band of snow over the southeast
half of the forecast area. Raised pops to likely southeast of
a line from Waupaca to Sturgeon Bay. Only forecasting accums
of an inch or less for now, but locally higher totals are
possible, as tonight`s event clearly illustrated.

Issued at 452 PM CST Wed Jan 11 2017

Radar, observers and web cams indicate snow, sleet and possibly
some freezing rain occurring southeast of a line from Wautoma to
Appleton to Kewaunee. RAP model had a good handle on pcpn trends
associated with the pcpn band, which was being generated due to
mid-level frontogenetic forcing and the LFQ of a 140 kt upper
level jet. Models show this band quickly exiting by mid-evening.
Expect snow/sleet accumulations of 1 to 3 inches, with a light
glaze of ice also possible. Hazardous travel conditions warrant
the issuance of a winter weather advisory til 9 pm.

.SHORT TERM...Tonight and Thursday
Issued at 304 PM CST Wed Jan 11 2017

Next 12 hours continues to be active as various upper jet
features working with a baroclinc zone over the region.

Early this afternoon, RRQ dynamics with an upper jet with the 700
mb fgen region over northern Wisconsin is loosening its grip.
Radars show a diminishing trend with visibilities improving early
this afternoon. Advisory ending by 3 pm looks good.

Next focus is redevelopment of precipitation this afternoon and
into this evening over the southeast half of the state. This
precipitation is associated with a surface wave riding along the
surface front which at 19z extended from Kansas City to Milwaukee
to northern Lower Michigan. The surface low is expected to be
aided by the LFQ region of another upper jet. The GFS is
producing 0.25 inches of qpf from 21z-00z this afternoon east of
the Fox river while the NAM is producing slightly less. The short
range RAP and HRRR were also producing a narrow 0.25 inches for
this same area and time period. Forecast soundings were suggesting
snow but mixed with sleet at times. Freezing rain is also
possible toward southern Manitowoc county.

Area radars were showing increasing returns the southeast third
of the state including northeast iowa, but little ground truth so
far. If this mixed precipitation can get its act going, will be
impacting east central Wisconsin during the late afternoon and
early evening commute. Since this is in the development phase,
will continue with higher end pops and keep the sps running for
this potential. But a short term advisory for EC WI not off the
table yet.

Will keep chc pops going Thursday morning until the weak 850 mb
trough with baroclinic zone departs the area. Otherwise drier
colder air on westerly winds will work into the region later

.LONG TERM...Thursday Night Through Wednesday
Issued at 304 PM CST Wed Jan 11 2017

The medium range models show a quieter pattern developing later this
week, when a closed upper low moves across the southwest conus,
leading to split flow across the majority of the lower 48.  This
southwest upper low may impact our region around the early or middle
of next week.  Prior to this, forecast will largely revolve around
temps and minor precip chances.  Will put more weight into the ecmwf
for this forecast.

Thursday night through Saturday...Will see clear skies for Thursday
night, but arctic high pressure will be building towards the area,
with cold advection continuing through the evening.  Northwest winds
will be especially breezy during this time, though they will lighten
up some late.  As temps fall through the single digits and teens
below zero, wind chills will drop into the 20s below zero over
central and north-central WI overnight into Friday morning.  A wind
chill advisory will likely be needed.  Continued very cold on Friday
with mid and high clouds increasing ahead of weak shortwave energy.
This shortwave could bring a light snowfall to central and northeast
WI on Friday night.  QPF is relatively meager so perhaps a dusting
is possible. That snow will pull out late Friday night, and arctic
high pressure will return for Saturday, with temps returning into
the 20s.

Rest of the forecast...High pressure will continue to stick around
on Sunday and Monday morning, with near normal temps.  Then will be
watching the upper low lifting northeast out of the Central Plains
for Monday afternoon into Wednesday.  Temperatures will be warm
enough ahead of the system for a wintry mix, so too early to
estimate potential snowfall/ice accumulations.

.AVIATION...for 06Z TAF Issuance
Issued at 1030 PM CST Wed Jan 11 2017

Main focus will be on the southeast portion of the forecast area,
where another band of snow is expected to redevelop late tonight
through mid-morning Thursday. MVFR/IFR conditions are expected
with the snow event, especially at the GRB/ATW/MTW TAF sites.
Farther northwest, anticipate mainly VFR conditions, though there
will be some lingering MVFR ceilings in north central WI early in
the TAF period. These should remain north of RHI. Otherwise,
clearing is expected across most of the region during the late
morning and afternoon on Thursday.



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