Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 222130

Area Forecast Discussion
National Weather Service GLASGOW MT
230 PM MST Wed Feb 22 2017

.SHORT TERM...for northeast Montana...tonight through Fri...

The base of a broad upper trough has descended south into the
Baja where it`s picking up moisture off the warmer Pacific. This
has spread scattered moisture over the Western States. The base of
the trough will dig across the Great Basin, undercutting Montana
for the most part. The trough is split with the Arctic portion
centered over Hudson bay. An associated short-wave rotating around
the Arctic low will cut through the western Prairie Provinces to
send a front into Montana tonight. This will keep the chance of
light snow and mixed precipitation going tonight through at least
Friday. Accumulation will be limited. WSW for Southwest Phillips
goes until midnight tonight when snowfall is expected to end.

With no strong winds in the forecast, weak CAA will cause
temperatures to drift lower, with Friday expected to be the
coldest day of the short term period, but near normal.


.LONG TERM...Fri night through Wed...

The main story during this period will be the cold temperatures.
Some occasional light snow can be expected too but nothing more.

Slightly warmer conditions are expected at the end of the period
with a NW flow ensuing as the upper trough moves to our east. Look
for temperatures to return to near normal about the middle of
next week. TFJ

Previous Discussion...
Synoptic Setup: long range begins with a large trough of cold air
spread out from The Pacific Northwest to Upper Mississippi Valley
and from the central US plains back up into Nunavut. Upstream a
weak ridge is nosing into British Columbia from the Gulf of
Alaska with another trough behind that over Alaska and a ridge
over the Bearing Sea.

Friday night through Saturday: Trough will clear out of the area
but Pacific moisture in a shortwave upstream will bring a small
chance for snow showers across the region during these periods in
addition to lower stratus.

Sunday to Sunday night: Meso-ridge upstream from British Columbia
moves through and clears the skies as well as slightly warming
the region briefly.

Monday into Tuesday: Alaskan trough moves down over the Pacific
Northwest and California. This will push a southwestern to zonal
flow with extra moisture over the region. However, model spread
begins to break apart here and confidence drops off to slightly
below average.

Tuesday night onward: Model confidence from this point onward is
shot as there is disagreement as to how/when the new PACNW trough
moves across the CONUS. These differences produce many solutions
to precipitation and temperatures over the area. Therefore,
confidence is low here-on. GAH




Look for conditions to gradually improve this morning, but
ceilings will fall again tonight. MVFR/low VFR clouds will
remain for the next couple of days. TFJ



Ice jams continue at some of the sites.

Slow but steady rises continue along the Milk River in Valley
County although stream levels have stabilized. Flood watch
continues mainly for the Milk River.

Ice jams are causing water levels to fluctuate on the Yellowstone
River near Glendive this morning. No flooding has been reported
so the Flood Watch remains in effect for Dawson and Richland

The water level on the Big Muddy River near Antelope is nearly
steady. Plugged culverts in the area appear to have been cleared.
A Flood Watch remains in effect here.

Some county controlled low water crossings over the area do have
water running across them.

The Frenchman River in northeast Phillips county continues to
rise. A Flood warning is in effect here. Ebert/sct


Winter Weather Advisory until midnight MST tonight for Southwest

Flood Watch through Friday afternoon for Central and Southern


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