Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 042052

Area Forecast Discussion
National Weather Service Missoula MT
252 PM MDT FRI SEP 4 2015

...Cold & Wet Labor Day Weekend with Snow Above 6500ft...

.DISCUSSION...Models have changed very little over the past 12
hours, so only minor adjustments were made with an emphasis placed
on refining the details of heaviest precipitation placement along
with the threat of mountain snow.

First, let`s talk snow! We issued a Winter Weather Advisory above
6500ft for the higher terrain along the Continental Divide. This
is primarily for those with plans to adventure in the mountains
and back country this weekend. But do anticipate accumulating snow
at some more frequently traveled locales, such as: Logan Pass in
Glacier National Park, Skalkaho Pass in the Sapphire Mtns.,
perhaps briefly over Lost Trail Pass in Lemhi County; Gilmore
Summit and Williams Creek Pass all will see the threat for
accumulating snow. So those with travel or back country adventure
plans in western Montana should be prepared to encounter winter-
like conditions developing Saturday afternoon and persisting
overnight into Sunday morning.

As far as rain goes, the forecast was adjusted somewhat to account
for some subtle changes to the overall path of the upper level
low. In general, the trend has now placed more precipitation
across NW Montana and especially along the Continental Divide
(think Bob Marshall Wilderness & Glacier National Park) while
suggesting slightly lesser amounts falling over SW Montana and
north central Idaho. So plan for cold, wet conditions this
weekend, even if you don`t plan to be in the high country. This
storm system will be a significant rain maker for many locations
and likely present a near death blow to many area wildfires. ~IV

Showery conditions will persist Sunday with the best chance for
rain lingering across NW Montana and along the Continental Divide.
Showers will again linger on Monday as the main trough passes to
the east and a weak shortwave arrives from the west. A general
drying and warming trend is expected for the rest of next week
with westerly flow to develop. High temperatures will return to
near normal (mid 70s) for the second half of the week.


.AVIATION...A narrow band of precipitation will continue to impact
KBTM and KSMN causing low ceilings and reduced visibility. This
band will shift off to the east. As the low pressure system moves
into the area showers will increase in coverage tonight. All
terminals will be impacted by low ceilings and periodic reduced
visibility. Mountains and passes will be obscured much of the
night due to the low clouds.


MT...WINTER WEATHER ADVISORY from Noon Saturday to 9 AM MDT Sunday
     ABOVE 6500 FEET for the Bitterroot/Sapphire Mountains...
     Butte/Blackfoot Region...Potomac/Seeley Lake Region.

     WINTER WEATHER ADVISORY from Noon Saturday to 9 AM MDT Sunday
     ABOVE 6500 FEET for the West Glacier Region.

ID...WINTER WEATHER ADVISORY from Noon Saturday to 9 AM MDT Sunday
     ABOVE 6500 FEET for the Eastern Lemhi County...Western
     Lemhi County.


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