Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 061645

Area Forecast Discussion
National Weather Service GLASGOW MT
945 AM MST Tue Dec 6 2016

.SHORT TERM...for northeast through Thu...

Being that wind chill advisory and it/s impacts are of main
concern now, looked into that closer and have extended it to 11 am
Wednesday for most of the CWA.

Little snow if any snow is now occurring with Fort Peck Lake
generating some awesome clouds and possibly some snow SE of it
this morning. As winds decrease tonight, the lake effect snow
machine may become more active. TFJ

Previous Discussion...
Weak radar returns continue across the northeast zones very
early this morning. Nearby observations show visibility improving
however, and this is confirmed by Sheridan County Dispatch.
Therefore, the winter weather advisory is no longer in effect.

A broad upper level trough will continue over the area for the
next couple of days. Along with these lower 500mb heights has come
a bitter cold Arctic air mass with temperatures in the single
digits and gusty northwest winds. Wind chills near -20 have
developed and a Wind Chill Advisory is in effect for much of
northeast Montana. As this is the first of the season, perhaps
coverage was a bit generous but decided to play it safe to drive
home the message on the colder temperatures, especially
considering how mild it has been leading up to this.

The next shift will be able to determine what will be the
appropriate coverage for tonight. As winds appear lighter tonight,
wind chills will barely reach 20 below in some places. However,
given some snow cover, temperatures are expected to be below zero.
As a result, it will not take much wind to generate 20 below wind

By Thursday, the trough axis will push east bringing northwest
upper flow over Montana. Arctic conditions will remain in place,
however, with model 850mb temperatures still hovering around -20C
near the Canadian border and -16C in the southern locations
throughout the CWA. Maliawco

.LONG TERM...Thu night through Tue...

Pattern with longwave trof over North America is expected to
persist through early next week. Slight shortwave ridge occurs
over the northern Rockies late in the week but is quickly
suppressed by shortwaves dropping out of the arctic.

Arctic high slides into the northern plains by midweek as slight
ridge develops in over the Rockies. By Thursday night a shortwave
pushing through the northern Rockies will begin to spread Pacific
moisture over the lingering cold air in central and eastern
Montana. Light overrunning snow is expected to spread east through
the day on Friday. Chances of snow continue into Saturday as a
shortwave trof drops through the region before spinning up a
Colorado low. A slight lull is expected on Sunday as the Colorado
low lifts toward the upper Midwest. By Monday the snow chances
return along with another surge of cold air as additional
shortwaves drop across the region. Ebert



As the backside of the departing storm system spins over the
Dakotas this morning, a lingering MVFR cloud deck will continue to
impact KOLF of KSDY through part of the day.

Expect VFR conditions to generally prevail. Gusty NW winds may
blow around the newly-fallen snow but should not impact
visibilities greatly. The strong arctic air mass and high surface
pressure should clear out the skies over the next several days.



Wind Chill Advisory until 11 AM MST Wednesday for Central and
Southeast Phillips...Central and Southern Valley...Daniels...
Dawson...Eastern Roosevelt...Garfield...McCone...Northern
Phillips...Northern Valley...Richland...Sheridan...Southwest
Phillips...Western Roosevelt...Wibaux.


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