Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 161716

Area Forecast Discussion
National Weather Service Glasgow MT
1016 AM MST Tue Jan 16 2018

Going forecast appears to be in good shape. I let the Wind Chill
Advisory expire at 10 am as wind chills remained close to -20 in
some areas (Glasgow, Sidney and Glendive). Did cool temps in most
valley locations as steep inversion and little mixing will inhibit
warming. Otherwise, temps above zero will be a welcomed change
today for most.

Rest of forecast looked good. TFJ

Previous Discussion...
...Dangerous wind chills at times through This morning...

Arctic high pressure currently in the Dakotas early this morning
will move to the east today. Meanwhile, an upper ridge will build
into Montana today bring dry and warmer weather. Shallow
inversions will keep most of the valleys colder than nearby ridges
today. Also, very cold start in most areas will require some time
to warm.

Warm air advection tonight with upper ridge moving into Eastern
Montana will limit how much fall for lows tonight. West winds will
develop around midnight tonight as a warm front passes through the
areas which will bring rising temperatures overnight.

Shortwave trough moves through the area on Wednesday flattening
the ridge somewhat. At the same time, it will bring somewhat
stronger west winds which will provide better mixing. Temperatures
will rise to above freezing in most areas and be 10 to 15 above
normal for highs.

The ridge rebounds Wednesday Night and Thursday with the warm and
dry weather continuing.

Flow aloft turns to the southwest Thursday Night and Friday as
the ridge moves to the east and an upper trough moves inland from
the Pacific. A shortwave trough on the SW flow aloft will move
through Eastern Montana Thursday Night and bring a cold front
through the forecast area. There will be enough moisture that gets
east of the Continental Divide for a chance of mixed precipitation
depending on temperatures. Friday will be mainly dry and cooler as
moisture moves to the south with the cold front.

The upper trough splits Friday Night and Saturday as the southern
branch trough digs south into the Desert SW and a much weaker,
drier and nearly zonal northern branch trough moves east along
the MT/Canada border. The forecast area might see a slight chance
of snow on Saturday from the northern branch trough.

Shortwave ridge will bring dry weather on Sunday with near normal

Models differ on timing of shortwaves troughs early next week with
a cold front that will bring somewhat colder temperatures into the
region. Forrester



SYNOPSIS: High pressure will move to the east today. KSDY and KGDV
may see mid level clouds at times this morning. Otherwise, look
for mostly clear skies today. A warm front will move through the
area tonight with mostly clear skies.
WIND: East at 10 to 15 knots at KGGW, south to southwest around
10 knots at KGDV and KSDY and light and variable at KOLF today.
West wind around 10 knots will develop behind a warm front




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