Area Forecast Discussion
Issued by NWS Glasgow, MT
FXUS65 KGGW 170931
Area Forecast Discussion
National Weather Service GLASGOW MT
231 AM MST Tue Jan 17 2017
.SHORT TERM...for northeast Montana...today through Thu...
Synoptic Setup:short term begins with a large ridge nosing in
over California and Oregon running over the intermountain west
and spilling over the Montana Front range where it is forming a
chinook and finally cresting over Manitoba and The Dakotas.
Farther west a large trough is forming over the northeast Pacific
behind the ridge. Most of the coldest air of the north hemisphere
is being held in place over Alaska and its north slope.
Today through Thursday: Chinook ridge will bring warming
conditions over the next 3 days with highs above freezing,
especially over higher terrain. River valleys will struggle to
make it out of freezing today due to missing sufficient shortwave
radiation to melt through snow and warm the ground in addition to
mixing out the inversion fully. Chinook winds should easily
transport excess moisture away from their origin point of snow
melt... so low stratus and fog will be hard to create until night
time. Chinook should begin lightening by Thursday and this may
allow some low stratus to form and stay in place longer than the
other periods. GAH
.LONG TERM...Thu night through Tue...
Flow aloft will be 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 southwest part of the
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 Saturday Night and Sunday bringing
chances for light snow 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. A shortwave ridge will bring dry weather to the area on
Monday. Then, the upper low that will be off the BC coast over the
weekend, moves inland as an upper trough early next week and
could bring a chance of light snow to the forecast area on
FLight Category: VFR.
Synopsis: Upper level ridge today will keep skies either clear or
with some high clouds. Shortwave trough tonight will bring an
increase in mid level clouds. With a shallow inversion in place,
LLWS may occur at times today and tonight. KGDV and KSDY will have
south to southwest winds around 10 knots today and tonight. KOLF
will have light and variable winds. KGGW will have mainly
southeast winds around 10 knots.