Area Forecast Discussion
Issued by NWS Missoula, MT

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37
000
FXUS65 KMSO 301129
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
429 AM MST FRI JAN 30 2015


.DISCUSSION...A ridge of high pressure will continue to be the
dominant feature over the Northern Rockies today causing another
morning of fog. The valleys of northwest Montana and north central
Idaho is once again experiencing widespread fog with a few
locations being dense. The fog is expected to diminish by late
morning and early afternoon, but strong valley inversions will
keep warming fairly minimal today.

A weak disturbance is still anticipated to drop out of Alberta
Canada on Saturday which will cause the upper level flow to become
more northwesterly in nature. This feature will cause light snow
to areas along the continental divide, particularly Glacier
National Park. A cooler modified-arctic airmass looks to spill
westward across the Divide and into western Montana Saturday into
Saturday night.

On Sunday, the upper level pattern begins to transition to
westerly flow. This pattern will allow a plume of moisture to
make its way towards the Northern Rockies. By Sunday afternoon,
many locations across northwest Montana, Clearwater and Idaho
counties should be experiencing widespread precipitation. The
cooler airmass could cause minor travel impacts with light snow
accumulations for much of western Montana, as well as some higher
elevations of central Idaho.

For Monday night through early Wednesday, confidence is
increasing for another shot of widespread precipitation. Some of
the forecast details remain hazy however as models continue to
change their minds with the handling of colder air backed up east
of the Divide. The latest models are no longer showing the cold
air spilling through our area Monday, but remaining east of the
Divide. This is in contrast to yesterday when they showed a
potential overrunning situation with impactful snow for much of
western Montana. If instead warmer air moves in aloft as models
indicate this morning, we could be looking at a complicated wintry
mix situation, mostly for western Montana. If colder air spills
through the area, widespread snow to valley floors is possible. In
summary, confidence is high for a wetter period but low for type
and amount of precipitation. Higher elevations will almost
certainly see several rounds of a few inches of snow, with
possible travel impacts as a result.

Weak ridging over the Northern Rockies should bring quieter
weather midweek, though lingering showers cannot be ruled out
(mostly over the higher terrain). Wet weather could return by late
next week, though forecast confidence is limited at this time as
models are struggling to figure out when and how much the ridge
will flatten to allow wetter weather to reach our doorstep.

AVIATION...Fog has once again developed in the valleys of
northwest Montana and north central Idaho this morning, especially
at KGPI. The fog will be dense at times, but is anticipated to
start dissipating after 30/1300Z. The low level moisture at KSMN
has lifted to a fairly low stratus deck tonight. This stratus will
linger across valley until early afternoon. KMSO could once again
experience patchy shallow fog during the early morning hours.

&&

.AVIATION...Fog has once again developed in the valleys of
northwest Montana and north central Idaho this morning, especially
at KGPI. The fog will be dense at times, but is anticipated to
start dissipating after 30/1300Z. The low level moisture at KSMN
has lifted to a fairly low stratus deck tonight. This stratus will
linger across valley until early afternoon. KMSO could once again
experience patchy shallow fog during the early morning hours.


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

$$



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.