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Area forecast discussion 
National Weather Service Glasgow Montana
926 am MST Thursday Dec 25 2014

Short term...for northeast through Saturday...

No change to the forecast for the morning update. There is light
snow up in Canada and snow just south of the County Warning Area with a little
near southern Petroleum and southern Garfield counties. Short term
models show some light snow possibly moving into the area from the
north after midnight...but none until then. Most of the activity
with the long wave system is going south of the County Warning Area. North surface
winds will keep a lid on temperatures and make Friday morning much
colder than recent history. Current forecast package handles these
elements well. Martin

Previous discussion...
upper low dropping through the Great Basin pulling
moisture southward. Snow tapering off across the region and will
go ahead and drop the advisory. Low cloud pressing south from
Canada with the cold air and winds increasing a little with cold
air advection today.

Weak shortwave swings through southern Saskatchewan tonight into
Friday with the potential for a little light snow.

Next system associated with shortwave sliding down the British Columbia coast
will begin to push some warmer air across The Divide on Saturday.
This will edge the Lee/Arctic boundary eastward and provide focus
for the next round of snow. Ebert

Long term...Saturday night through Thursday...

A large long-wave trough develops over Continental U.S.. the trough will
anchored by an Arctic low near Hudson Bay. The cold air of this
trough will keep much of the the extended period colder than

The period starts with northwest flow aloft over northeast Montana
and the modified Arctic boundary stretching northwest to southeast through
southern Saskatchewan. Off to the west a short-wave disturbance
will kick across Vancouver Island to send Pacific moisture over
The Divide. The short-wave deepens the western portion of the
trough and drags the boundary further south across the forecast
area. Overrunning moisture will spread snow along the frontal
boundary essentially along the same track as the Christmas evening
storm. Expect snow to spread across central and southeast Montana
and the southwest portion of nemont. So by Sunday evening the snow
will have moved out of the area to be followed by much colder air
of a polar surface high.

A large ridge off the West Coast will move in behind the amplified
trough to being about a return to near normal temperatures after




The base of the large western trough will continue south today
taking the cold front and snow well to the south. A surface high
slides into the area from the north. MVFR stratus has spread over
northeast Montana this morning. This is expected to dissipate by

Expect a northerly breeze today at around 10kt.


Glasgow watches/warnings/advisories...none.




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