Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service Missoula Montana
247 PM MDT Thu Apr 24 2014

Discussion...an upper level wave will move across central Idaho
into western Montana this afternoon through this evening. This
feature will be responsible for scattered rain and snow showers,
some of which could have an embedded thunderstorm. Expect an
occasional lightning strike, gusty winds and pea-size hail with
these storms. Snow will most likely continue at times at area
passes above 5,000 feet, but will not stick to the Road surfaces.
There could be some slush at times after the most intense showers
through the evening.

A brief respite is on tap tonight through Friday morning across
northwest Montana before the next system is expected to move in.
An area of rain and snow is expected tonight across central Idaho
and the snow level could lower enough to affect whitebird grade on
US-95. If that happens there could be a period of snow
there Friday morning with the biggest impact being some slush on
the roadway melting away by late morning.

This weekend...another Spring storm system will impact all of the
northern rockies in some way. A low pressure system will develop
on the leading edge of an approaching upper level trough from the
west Friday afternoon. Central Idaho and southwestern Montana will be
impacted first, with moderate to heavy mountain snow above 5000
feet, and rain at valley floors. There is also a possibility of a
few thunderstorms developing in these same locations. The low
pressure system will then move northeast overnight Friday through
western Montana and across The Divide near Glacier National Park.

The higher elevations of central Idaho and southwestern Montana
including Lolo Pass, MacDonald Pass, and Georgetown Lake, could
pick up around 3 to 5 inches of snow, by early Saturday morning.
Areas along the Continental Divide, such as Glacier National Park
and Marias Pass will be hit the hardest where 6 to 10 inches of
snow is expected by Sunday morning. All other valley locations in
western Montana and central Idaho can expect a wide range of rain
amounts from .30 to .75 inches.

There is however one scenario that could play out that would give
extreme northwest Montana such as Lincoln County much more
precipitation than forecast above, possibly an inch of rain in
Yaak and Libby. Not to say that this will occur, it's just one
piece to this complex system. Keep apprised to your local forecast
for any changes in the coming days.

Sunday and Monday...some residual showers from an exiting low
pressure trof are expected across the region Sunday and again
Monday. However less coverage is anticipated Monday.

Tuesday through Thursday...mainly dry conditions! Finally a
break in the wet weather is becoming more apparent for the
middle of next week. Models are advertising a high pressure
ridge over the region. There are some disagreements for the
placement of the ridge, just a bit further west or directly over the
northern rockies. Either way conditions are expected to be mainly
dry under this pattern. Above normal temperatures are expected
Wednesday and Thursday. Normal highs for the end of April are in the
lower to mid 60s.



&&

Aviation...numerous rain showers will persist across the entire
northern rockies through the evening hours. There will be a brief
break in the rain before it picks up once again around noon
Friday. All terminals will be impacted with lowering ceilings,
reduced visibilities and mountain obscurations.
&&

Mso watches/warnings/advisories...
Montana...none.
Idaho...none.
&&

$$

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