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000
FXUS65 KMSO 192044
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
244 PM MDT Wed Jun 19 2013

...SIGNIFICANT PRECIPITATION THROUGH THURSDAY MORNING...
...LIGHT SNOW ACCUMULATION ABOVE 6000 FEET TONIGHT...

.DISCUSSION...A low pressure system currently located in central
Washington and Oregon will continue to slowly move eastward into
western Montana and north central Idaho tonight. This feature has
abundant moisture and energy associated with it which will lead to
an active period for the next 24-36 hours. Below is a summary of
the main impacts:

Thunderstorms: General thunderstorms are expected this afternoon
and evening across western Montana. A few storms could briefly
become strong this afternoon, mainly across southwest Montana and
along the Continental Divide through Powell County. While the
stronger storms should be fairly isolated and short lived, a few
could produce gusty winds, small hail and very heavy rain.

Heavy rain: Moderate to heavy rain will continue this afternoon
and overnight. The heaviest amounts are expected through north
central Idaho up into northwest Montana. Some locations along the
Idaho/Montana border have already received up to an inch of rain
fall, with another 0.50-1.00 inch of rain possible by the end of
Thursday. Flooding is not expected to be an overall issue although
small streams and rivers will likely begin to rise. Additionally,
some ponding of water on the roadways and in urban areas is possible.

Snow: Snow levels are expected to drop by Thursday morning to
about 6000 feet. This will allow for some accumulating snow in the
higher terrain as well as high elevation passes, such as Lost
Trail. Those planning to be in the high backcountry should be
prepared for wet, raw weather conditions.

The upper level low pressure system will slowly move through
the region, continuing a wet and cool pattern through Saturday.

A brief break in precipitation is expected Saturday evening into
Sunday morning as a ridge of high pressure builds into the region.
This will be short lived however as the ridge quickly moves
eastward leaving western Montana and north central Idaho in a
moist southwest flow through mid week. Although temperatures will
warm back towards normal, showers and thunderstorms will continue
to be a possibility.

&&

.AVIATION...

A broad storm system will exist over the Northern Rockies during
the next 24 hours. Each of the four air terminals will experience
occasional vicinity thunderstorms through 20/0600Z, with only
rain showers present at times thereafter. Widespread rainfall will
exist for much of the next 24 hours for KGPI and KMSO, lowering
ceilings and visibilities at times. Terrain obscurations will be
commonplace during this time as well. KSMN and KBTM should
experience improved flying conditions after 20/0600Z.

&&

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

$$

Kitsmiller/Zumpfe

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