Area Forecast Discussion
Issued by NWS Missoula, MT
FXUS65 KMSO 302206
Area Forecast Discussion
National Weather Service Missoula MT
306 PM MST FRI JAN 30 2015
.DISCUSSION...The persistent fog and low stratus up in the valleys
of northwest Montana is expected to continue through the rest of
the evening and through Saturday morning. The fog should lift to
more of a stratus deck as a weak disturbance moves in tonight. The
weak disturbance could bring light snow flurries and will mainly
be along the Continental Divide. Marias pass could see up to one
inch of snow and northwest Montana valleys could see possibly a
trace to half inch of snow tonight through Saturday.
A more widespread weather disturbance with be moving in Sunday
afternoon. This weather system is expected to bring 2 to 5 inches
of snow to Mountain passes Sunday evening through Monday morning.
Valleys above 3000 ft for north central Idaho and western Montana
will see a rain/snow mix with light accumulations possible.
Valleys of northwest Montana will see slightly lower snow levels
and could see 1 to 2 inches of snow during the same period.
Monday and Tuesday...Another weather disturbance will move through
the region. This system is supported with more moisture and a stronger
jet stream. Mountain passes can expect several inches of snow,
however temperatures will be warm enough in the valleys to bring
more of a mix rain and snow through Tuesday morning. Cooler air
will settle over the region Tuesday afternoon to bring snow levels
to the valley floors but at this time snow is expected to be more
showery with little accumulations expected. It is possible snow
banding could set up behind this exiting system. Though confidence
is low at this time for snow bands but will be monitored the next
few days as this would be a snow impact for the valleys of
Moist unstable or showery conditions continue through Friday with
snow levels anticipated to rise to above pass levels.
Models have been showing that a strong jet and abundant sub
tropical moisture in the central Pacific will impact the western
U.S. late next week and weekend. These are the ingredients for
significant orographic lift aka precipitation in the mountains.
Given the origin of these systems snow levels are expected to be
on the increase. Confidence is increasing for this pattern change
but pretty low for timing and especially snow level/precipitation
type in the mountains.
.AVIATION...Persistent fog and low stratus will continue at KGPI
and KSMN through this evening and Saturday morning. A weak
weather disturbance moving in tonight may bring some light
flurries at KGPI. This could help lift the fog to a low stratus
deck but nonetheless KGPI will continue to see visibility and
ceiling reductions through the first half of Saturday. KMSO could
see another morning of patchy river fog.