Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 171026

Area Forecast Discussion
National Weather Service Missoula MT
326 AM MST Sat Nov 17 2018

.DISCUSSION...A ridge of high pressure is building over the area
quickly today, and will last the next several days. The stable
conditions under the ridge will trap cold air in area valleys
keeping temperatures below average into next week. The wild card
in the forecast is how much low cloud and fog will develop, as
this will have a large impact on the temperature forecast. For the
remainder of the weekend and early next week we trended
temperatures warmer but remain on the cold side in the valleys.
Even if we don`t have a lot of low clouds and fog, the stable
conditions will cause stagnant air and increasing haze, especially
early next week.

Thanksgiving appears to be unsettled with a Pacific trough
approaching the west coast. Precipitation type will depend on how
much cold air valleys will produce with the prior ridge pattern.
At this time there is medium confidence that there will be a
chance for mountain pass snow and light valley mixed precipitation
or snow.

There is reasonable agreement from model guidance that the trough
will move onshore the day after Thanksgiving into the weekend.
This could provide wintry impacts for both mountain and valley
locations. Stay tuned.


.AVIATION...Some low and mid clouds remain trapped in the area
this morning as a ridge of high pressure quickly builds in. Dry
air moving in under the ridge will help erode those clouds today,
and though timing any clearing remains a challenge MVFR conditions
at worst are expected today.



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