Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Glasgow Montana
844 PM MST Thursday Dec 25 2014
Short term...for northeast Montana...tonight through Saturday...
update... skies remain cloudy over most of northeast Montana this
evening. There is an area of clearing near Wold point at 04z.
While low clouds gradually clear... higher clouds are expected to
move in overnight. Going forecast looks reasonable for now. Forrester
Previous short term...
main longwave trough has dug itself into The Four Corners area
with the surface low well south of Montana. This has left the County Warning Area
out of areas receiving snow today. Cold air...however...does
following behind this system across Montana with northerly flow
through this evening that will make the next couple days closer to
seasonal normals and much colder than recent history. 10 to 15 miles per hour
northerly winds today will slacken tonight to around 5 miles per hour and be
more variable through Saturday.
There is a chance of some light snow Friday late morning and
afternoon as a small shortwave moves down from Alberta across the
area. Limited forcing and very limited moisture suggests only
slight amounts of snow...most likely less than half an inch.
Canadian radars have been showing some light snow at times
upstream with this system...so do expected some patches of light snow
tomorrow in NE Montana as system passes. Martin
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
MVFR ceilings may improve for a time after 06z but MVFR ceilings and
visibility will again be possible as a storm system moves across
the region Friday morning along with light snow showers. Winds are
expected to be light and variable through the taf period. Maliawco