000
FXUS65 KMSO 201002
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
402 AM MDT Mon May 20 2013

.DISCUSSION...If you were hoping for a break in all the rain,
today and tomorrow are your lucky days! Conditions today will see a
much drier trend as the system still rotating just east of the
Continental Divide finally exits and allows the Northern Rockies
to finally dry out a little. Before it does so, a few light
showers will still linger along the Divide, but should diminish as
the day progresses. Temperatures will see a jump back into the
upper 60s to mid 70s, with even warmer and drier conditions for
Tuesday. Confidence is still high that the region`s warmest day
will be Tuesday afternoon. Many locations, especially those in
central Idaho, could hit the 80 degree mark.

Sadly, this will come to an abrupt end as the system being spoken
of in previous forecasts finally steps into the picture. This will
be a very large, closed low pressure system that will edge off the
Pacific Coast. As it does so, it will remain there for several
days, with very little movement eastward. This means that a
steady, moderate to heavy period of rainfall is possible for
western Montana...especially Glacier National Park, and across
northwest Montana, beginning Wednesday. Winds will also develop
and increase, making for a very raw day.

A wave of heavier precipitation will slowly move through western
Montana overnight Wednesday, exiting into Canada Thursday
afternoon. However, significant residual moisture will abound
across the Northern Rockies for frequent showers throughout
the day Thursday. Thunderstorms will be possible over southwest
Montana during the afternoon, which could place an additional heavy
rain threat to the area. As depicted by models, these storms
will grow in number and coverage Thursday night into Friday morning
while they move north along the Continental Divide.

Yet another push of showers and possibly a few thunderstorms are
anticipated Friday afternoon, all associated with the stubborn cut
off low pressure system seemingly parked over the Pacific and
Inland Northwest states. Eventually this weekend the low appears
to move north into Canada and dissipate. However, broad troughing
will remain in place over the region and both the ECMWF and GFS
are showing yet another cut off low taking up residence over the
Pacific Northwest by the middle of next week.

&&

.AVIATION...Today will be much improved over previous days, with
cloud decks rising and precipitation finally ending across the
Northern Rockies. Some lingering low stratus and patchy fog has
been intermittent early this morning for KGPI, and is not expected
to last long after sunrise. Otherwise, light winds and calm
conditions expected through Tuesday.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

$$

Allegretto/Dickerson

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