Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 041641 AAA

Area Forecast Discussion...UPDATED
National Weather Service GLASGOW MT
941 AM MST Sun Dec 4 2016

.SHORT TERM...for northeast through Tue...

Sent an update this morning to try and give more detail to the
leading edge of precipitation ahead of the cold front today from
the west and northwest. Current regional radar reflectivities
showing some light precip between Havre and Great Falls with more
still upstream west of the Rocky Mountain front. Best model
consensus begins moving that scattered precip eastward into
eastern Montana in multiple light-impact waves starting by mid-
day. Models seems to be indicating that some of the precip will be
either virga or sprinkles/flurries for some locations through
tonight. At any rate, widespread or even highly concentrated
precip amounts are not expected across the CWA. That being said,
still the occasional brief shower is possible but is not expected
to be very impactful.


Previous short term discussion: Shortwave ridge will bring mainly
dry weather to the forecast area this morning. It will also be the
last warm day for a while as a cold front this afternoon and
evening will bring bitter-cold air into the region for most of
the week.

The upper trough moves into Western Montana this afternoon and
across Montana tonight and Monday. The models are splitting the
moisture around Northeast Montana with this system which will
result in little precipitation for most locations. Any
precipitation that does occur will start out as a mix of rain and
snow this afternoon and change to all snow this evening as strong
cold air advection moves in behind the cold front. Will have a
chance pops for this afternoon and tonight. Gusty northwest winds
will also develop this evening.

Cold air advection continues during the day on Monday with gusty
northwest winds which will result in steady or slowly falling
temperatures. Slight chances for snow will linger as upper trough
moves through the area.

Monday Night, temperatures will drop to near zero as northwest
winds remain strong enough to produce wind chills near 20 below.
Arctic high pressure will build into the area from Canada. A moist
atmosphere will keep skies cloudy.

Temperatures will not rise much on Tuesday as northwest winds and
cloudy skies continue.


.LONG TERM...Tue night through Sun...

The extended period begins Tuesday night into Wednesday with an
upper level trough firmly influencing conditions across the
forecast area. Given 850mb temperatures between -20 and -25 across
the CWA, expect frigid Arctic temperatures in place. With wind
speeds above 10 mph, wind chill concerns may develop, especially
as folks become adjusted to these conditions following what was a
fairly mild November as compared with average.

This air mass will remain in place through Thursday with lows near
or below zero and highs in the single digits. Wind speeds will
need to be followed for wind chill determinations but anyone in
the area should be getting prepared for several days of frigid
winter-like conditions.

By Friday models show a weak ridge moving across the Pacific
Northwest and into Montana and thereafter flattening. This will
enable a little moderating trend in temperatures before the next
shortwave approaches toward the end of the long term period. Pops
were carried for a slight chance to chance of snow but uncertainty
exists here due to large ensemble 500mb height spread by day 6 and




VFR conditions are expected this morning. Scattered snow showers
are expected late this afternoon and evening with a cold front.
Expect lowering ceilings and reduced visibility with this
activity. MVFR to IFR conditions may occur at times. Southwest
winds around 10 kts this morning will become northwest tonight and
increase to 10 to 20 kts with gusts in excess of 25 kts.





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