Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 251616
AFDGGW

Area Forecast Discussion
National Weather Service GLASGOW MT
916 AM MST Sat Feb 25 2017

.SHORT TERM...for northeast Montana...today through Mon...

Raised afternoon pops across the NE zones and added mention of
flurries and morning patchy fog. TFJ

Previous Discussion...
Shortwave dropping out of Canada this morning, pushed a band of
snow through eastern Montana overnight. Amounts were light but
have resulted in slick roads. Additional precipitation is expected
today before the shortwave moves into the Dakotas.

A weak shortwave ridge develops Saturday night temporarily ending
the snow threat although skies will remain cloudy.

The next shortwave trof to impact the area will feature an Arctic
wave which slides east through central Canada, but provides
another push of colder air to northeast Montana. Main portion of
the trof will move through the Great Basin on Monday. A weak
east-west convergence zone develops through central Montana to
provide focus for slight more intense snow Sunday night into
Monday. Ebert

.LONG TERM...Mon night through Sat...

Synoptic Setup: long range starts with a large trough over the
western third of the CONUS which runs north into an Arctic airmass
over the Canadian Shield. Upstream a ridge resides over the Gulf
of Alaska nosing on shore over the Yukon. Behind this is yet
another trough over Alaska.

Monday night through Tuesday night: Trough will move across the
areas bringing pacific moisture and increased PoPs.

Wednesday through Thursday night: Flow becomes Northwest as a the
ridge to the west builds. This will decrease PoPs slightly due to
lack of moisture, but quick shortwaves could still be caught in
the flow for isolated showers.

Friday: the Ridge itself will pass through the area. Warm up is
expected to be strong at this time. But model spread is wide so
this could change rapidly.

Friday night onward: At this point models present a large spread
of possibilities, from maintained ridge to Arctic plunge and
nearly everything in between. Confidence is practically non-
existent as of tonight with hope for better consistency by
tomorrow.


&&

.AVIATION...
VFR conditions may occur at times today, however, low stratus and
reduced visibility in snow showers associated with a proximal
frontal boundary will periodically lead to MVFR to IFR conditions
across area terminals. Occasional fog also may occur at times with
near-saturated boundary layer conditions. Winds will trend west by
late morning and continue through the afternoon at 5 to 15 kts
with occasional higher gusts. Maliawco


&&

.HYDROLOGY...

Ice jams and high water levels continue on the Yellowstone River
with continued fluctuating river levels.

In Dawson County, an ice jam raised levels overnight near
Glendive.

In Richland County, a reported jam from the DES was located
between Fairview and Sidney near the Richland Park.

With little change in runoff and melting of the ice jams expected
over the next several days, the Flood Watch was extended through
Monday.

Later next week, things could change a bit as warmer air could
melt or move ice jams along.

Elsewhere, some county controlled low water crossings in
Roosevelt County were reported this week. These will probably slow
by this weekend with the colder air.

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Monday afternoon for Dawson...Richland.

&&

$$

weather.gov/glasgow



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