Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 081601

Area Forecast Discussion
National Weather Service GLASGOW MT
901 AM MST Thu Dec 8 2016

.SHORT TERM...for northeast through Sat...

Going forecast in good shape and very little to change.

Will access the Wind Chill Advisory at around noon. Looks like it
will be allowed to expire then be re-issued for tonight. Bundle
up! TFJ

Previous Discussion...
Wind Chill Advisory remains in effect for the northern and
eastern zones until noon Today.

Canadian high pressure over eastern Montana early this morning.
Although winds have diminished across most of the area,
temperatures in the zero to 10 below range are keeping wind chill
cold enough to continue the advisory.

High pressure slides into the Dakotas today in response a slight
ridge pushing into the northern Rockies. Cold air will linger
across northeast Montana even as the ridge spreads moisture across
the divide. As this moisture lifts over the cold air, snow is
expected to develop over central Montana tonight. Snow will slowly
spread northeast for Friday and Saturday. Best chance of
accumulating snow will be late Friday night into Saturday morning
as a shortwave pushes through the northern Rockies. Ebert

.LONG TERM...Sat night through Thu...
The extended period gets underway Saturday night with fairly
zonal upper level flow across the region and a weak shortwave
pushing through the area with a little light snow.

As the wave departs and surface high pressure returns to the area
from Canada expect a reinforcement of Arctic cold air. By Monday
night model 850mb temperatures range from -20C to -27C across the
CWA. This weather pattern will help keep the track of shortwaves
embedded in the flow further south, and so expect any snow chances
to remain across the southern zones of the CWA during this time.

By the middle of next week an upper closed low will track across
Hudson Bay with an amplifying trough in the eastern U.S. helping
to develop a ridge across the Pacific shore. As this occurs the
flow aloft over eastern Montana into the rest of the Northern High
Plains will become northwesterly. Over time the ridge will
translate east, helping to spread higher 500mb heights across the
region and moderating temperatures, at least relatively speaking.
Look for high temperatures to perhaps make a run toward double
digits again by Thursday if this scenario pans out.

Latest 00z models show any ridge abruptly departing downstream
with a new shortwave trough developing over the western U.S. This
may initiate a new period of unsettled weather conditions, though
timing/placement of any snow is difficult at this time given large
ensemble spreads at these time scales. Nevertheless, it looks like
for right now at least, that things become more interesting toward
about December 15-16. As model consensus improves, more detail
will be able to be agreed upon, but for right now will introduce
slight chance to chance pops across the CWA to finish out the long
term forecast period. Maliawco



Flow pattern aloft is northwesterly based on a short-wave
disturbance in southern Saskatchewan. Low stratus surrounds that
low center and is affecting portions of Northeast Montana with low
stratus, possibly continuing throughout the day for the far
eastern areas. So expect MVFR ceilings this morning for terminal
areas SDY and GDV. Where low stratus doesn`t exist, expect clear
skies from the west.

Winds: northwesterly at around 5-10kt today, becoming light and
variable this evening, then becoming easterly later tonight at



Wind Chill Advisory until noon MST today for Central and
Southern Valley...Daniels...Dawson...Eastern Roosevelt...
McCone...Northern Phillips...Northern Valley...Prairie...
Richland...Sheridan...Western Roosevelt...Wibaux.


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