Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 160919

Area Forecast Discussion
National Weather Service GLASGOW MT
219 AM MST Mon Jan 16 2017

.SHORT TERM...for northeast through Wed...

Synoptic Setup: short term begins with a trough over the Dakotas
running into Wyoming and then down toward the Four Corners region.
A large Pacific Ridge nudges onshore over Washington and passes
over British Columbia, cresting into a Chinook over the Alberta

Today through Wednesday: cold air trough will continue moving
south as the chinook ridge to the north slowly drops over eastern
Montana through tomorrow. This will slowly raise temperatures
each period with downslope winds through Wednesday. Temperatures
may reach above freezing for most of the CWA by Tuesday and
continue on through Wednesday. However, snow-melt will lead to
excess moisture that could then generate fog and low stratus which
will take progressively longer to burn off each day and this may
keep temperatures down below predicted totals. But this aspect
will hinge almost entirely on light wind speeds. GAH

.LONG TERM...Wed night through Mon...
Upper ridge moves to the east on Thursday with mild and dry
weather continuing. Flow aloft turns southwest to southerly
Thursday Night and Friday as a broad upper trough moves into the
Western US with an upper low off the BC coast. A weak cold front
Thursday Night could bring a slight chance of rain and snow
showers to the southern part of the forecast area.

Temperatures will be some what cooler on Friday but still above
normal. Shortwaves within the broad upper trough will move north
across the Plain States between Friday Night and Sunday bringing
chances for light snow showers into the area. At the same time,
the main trough splits and the southern branch moves to the east
while the northern branch lifts north into the Canadian Prairies
by next Monday and an upper ridge builds into Montana with dry
weather. Forrester




SYNOPSIS: A warm, Pacific airmass will be in control much of this
week. High pressure today and tonight will bring mostly clear
skies to the area. Patchy fog is possible tonight.




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