Area Forecast Discussion
Issued by NWS Missoula, MT
FXUS65 KMSO 092138
Area Forecast Discussion
National Weather Service Missoula MT
238 PM MST Mon Dec 9 2013
.DISCUSSION...A moist northwest flow on top of the very cold
surface air was responsible for the areas of snow Monday. Another
more organized weather system will shift southeastward across
western Montana and north central Idaho tonight and Tuesday. This
should produce more widespread snow and poor morning driving
commute on Tuesday. The communities that should see the most snow
should be from Libby and Kalispell southward to Missoula and
Seeley Lake. Although, Orofino to Lolo Pass could also see a fair
amount of snow. The Camas Prairie may be the exception and more in
a downslope area with only light intermittent snow.
The cold air that has moved into the valleys will be slow to scour
out this week. All the model guidance is moderating the valley
temperatures much too quickly, as evident by today. However, a
slow moderation in temperatures can still be expected in the
valleys through the end of the week. The mountains will moderate
much quicker and back to more typical values or possibly above
normal by Thursday.
Regarding additional moisture after Tuesday... A northwest flow
should persist Wednesday, bringing some additional moisture across
the area. However, the moisture should be more in the form of
variable cloudiness than periods of snow. Although, some light
snow could persist into Wednesday.
A dry period is expected late Wednesday through Thursday as a weak
ridge of high pressure shifts across the area. This may produce
some partial clearing and allow areas of valley freezing fog to
develop by Thursday morning.
The next weather system is expected Thursday night into Friday.
There is still a fair amount of uncertainty with the amount of
moisture with this disturbance. Models are varying, with some
showing a split flow and very little precipitation and some models
showing another burst of snow. Based on some of the latest model
trends, we are leaning towards a little more precipitation. At this
time, it appears the precipitation should be the form of snow.
However, it is possible that patchy freezing rain may occur.
.AVIATION...Widespread terrain obscuration and light snow has
decreased some this afternoon, with the poorest remaining
conditions from KGPI to KMSO. Ceilings and visibilities should
again lower tonight into Tuesday as another weather system shifts
across the area. Expect widespread terrain obscuration to occur.
MT... WINTER WEATHER ADVISORY until 11 AM MST Tuesday
Bitterroot/Sapphire Mountains...Missoula/Bitterroot Valleys.
WINTER WEATHER ADVISORY until 11 AM MST Tuesday Kootenai/Cabinet
Region...Lower Clark Fork Region.
WINTER WEATHER ADVISORY until 11 AM MST Tuesday Flathead/Mission
WINTER WEATHER ADVISORY until 5 PM MST Tuesday Potomac/Seeley
Lake Region...West Glacier Region.
ID...WINTER WEATHER ADVISORY until 10 AM PST Tuesday Northern
Clearwater Mountains...Orofino/Grangeville Region...
Southern Clearwater Mountains.
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