Winter Storm Watch 8, NWS Missoula, MT

Area Forecast Discussion
National Weather Service Missoula MT
328 AM MDT Fri Sep 4 2020

.DISCUSSION...Hot and dry conditions will exist today and Saturday
across the Northern Rockies. In addition, a very mild night will
occur tonight into Saturday morning. By Saturday afternoon, winds
will increase across the entire region and become gusty by later
in the evening. As a result the existing low humidity, hot
temperatures, and windy conditions, a Fire Weather Watch remains
in effect for southwest Montana where critical fire conditions
will be most prominent as a result of this dangerous combination
of components. That being said, everyone should be wary of
creating a spark that could result in a new fire just about anywhere
in western Montana or north central Idaho, given how hot and dry
conditions will be!

Sunday will see a slight cool down and remain quite dry ahead of
a very unseasonably cold and wet weather system expected on
Monday. This system continues to have good forecast model
agreement and thus, moderate to high forecast confidence that
Monday (Labor Day) will be a tumultuous weather day. Strong winds
out of the east-northeast will create issues both on land and on
bodies of water as winds up to 35 to 45 mph will be commonplace.
Hazardous boating conditions should be expected on all area lakes,
but particularly those in and around Glacier National Park,
Flathead Lake, and the Seeley/Swan valley, where the strongest
winds are likely.

Another concern will be the threat for snow in the backcountry;
specifically elevations of 5000 feet and higher. With how much
cold air is associated with this Canadian low pressure system,
snow levels could drive down to as low as 5000 feet and will
create raw, cold, and wholly unpleasant backcountry conditions.
Anyone with recreation plans should anticipate and/or make
adjustments necessary for inclement conditions.

Rain will also be present in valleys, but should be mostly
confined to along the Continental Divide and likely no further
west than the Idaho/Montana border. As a result, north central
Idaho may only experience the much cooler temperatures and breezy
winds that occur with this system. Some higher terrain along the
Clearwater and Bitterroot mountains could pick up light snow
accumulations as well, though the more notable snow will again
exist along the Divide.

Tuesday will see a drying trend, but will be just as cool as
Monday for most locations. North central Idaho may start to
moderate in temperatures during this time, with the entirety of
the Northern Rockies region returning back to seasonable highs in
the 80s once more by Wednesday through the end of the week.

&&

.AVIATION...High pressure, warming temperatures (and higher
density altitudes), with generally terrain-driven winds should be
expected across the entire Northern Rockies today as high pressure
continues to dominate the weather pattern.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Fire Weather Watch from Saturday afternoon through Saturday
     evening Deerlodge/West Beaverhead...East Beaverhead.

ID...&&