Area Forecast Discussion
Issued by NWS Glasgow, MT

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289
FXUS65 KGGW 232040
AFDGGW

Area Forecast Discussion
National Weather Service GLASGOW MT
240 PM MDT TUE AUG 23 2016

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

A vertically stacked upper low continues to spin over southern
Saskatchewan, thus Northeast montana remains in a mainly dry
northwest flow aloft. A reinforcing shot of colder air will rotate
in out of Canada tonight...keeping winds breezy overnight.
Stronger cyclonic flow will keep a slight chance for showers in
the forecast, mainly near the Canadian border.

Breezy conditions will continue into Wednesday as the pressure
gradient remains tightened while the stacked low pushes into
Manitoba. Thus the lake wind advisory timing (through Wednesday
evening) looks on track. Temperatures will be unseasonable cool
while a bit more moisture rotates in from the northwest,
spreading chances for light showers southward across the entire
area.

Wednesday night high pressure will quickly build in, making for
quickly decreasing winds and shower activity wednesday evening.
Clouds will at least partially clear, allowing for a brisk night.

Thursday high pressure will dominate allowing temperatures to warm
and skies to continue to clear. Gilchrist



.LONG TERM...Thu night through Tue...
Few changes were made to the inherited long range period other
than populated temperatures and winds with latest consensus model
blends. Overall expect an end of week trough to push downstream of
the forecast area over the weekend with an upper ridge developing
over the Northern High Plains by early next week.

Weak embedded upper level disturbances may at times provide
enough forcing for ascent to initiate an isolated shower, though
conditions will likely be dry more often than not. Additionally,
the ridge will allow for rising heights and warm temperatures. As
the ridge axis slides east establishing south west flow aloft,
attention will turn to a new trough pushing across northwest
Montana toward the end of next week. The ECMWF and GFS agree on
the overall big picture bit differences exist in the details and
so will leave well enough alone for now. Maliawco

Previous Long Term Discussion...

Synoptic Setup: Long range begins with a large trough over the
high Plains of Montana running up through Saskatchewan and into
Nunavut. Hot high Pressure in entrenched over southern California
and western Arizona with a slim ridge running up the west coast
to central British Columbia.

Thursday night through friday night... period begins dry but the
center of the through impacts the region by Friday afternoon
introducing an increased chance for showers and thunderstorms
that last through the overnight hours.

Saturday onwards... chance for showers decrease at this point with
confidence dropping off post saturday night as a brief passing
ridge begins to exit the area. Models are unsure how to resolve the
features behind this ridge with strong disagreement among
different members. Zonal to southwest flow looks like a
possibility which may keep temperatures slightly cooler with semi
unstable flow each afternoon. Look for new runs to change this
portion of the forecast easily in the future. GAH


&&

.AVIATION...
VFR conditions are expected through the evening. MVFR to IFR CIGS may
impact terminals late tonight from the north. Gust northwest winds
of 20 to 30 kts with higher gusts will diminish this evening to 10
to 20 kts. Maliawco


&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Lake Wind Advisory until 9 PM MDT Wednesday For Fort Peck Lake
for Central and Southeast Phillips...Central and Southern
Valley...Garfield...McCone...Petroleum.

&&

$$

weather.gov/glasgow



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