Area Forecast Discussion Issued by NWS Missoula, MT
000
FXUS65 KMSO 190844
AFDMSO
Area Forecast Discussion
National Weather Service Missoula MT
244 AM MDT Tue Mar 19 2024
.DISCUSSION...Strong high pressure locked in over the Northern
Rockies will bring another spectacular spring day. Unseasonably
warm valley temperatures, some 10-15 degrees above normal, will
hover around the 70 degree mark. The lower valleys across central
Idaho will be in the mid 70s to around the 80 degree mark.
Above normal temperatures will continue into Wednesday for the
majority of the Northern Rockies, just not as warm as it has been
recently thanks to an increase in some cloud cover. Breezy west
winds will develop in the afternoon.
The ridge will begin to weaken late this evening as a Canadian
cold front banks up against the Continental Divide near Glacier
National Park. At the same time, moisture moving through the
northern periphery of the ridge, will allow for the development of
mountain snow showers over Marias Pass late Tuesday evening and
early Wednesday. A tightening easterly gradient ahead of the
advancing cold front will also introduce breezy easterly winds
along Highway 2 from Marias Pass to West Glacier Wednesday,
ushering in much colder air.
The colder Canadian air-mass will be slow to advance further south
into the rest of western Montana, not entering the rest of
northwestern Montana until late Thursday. A shortwave moving
onshore of the Pacific NW will bring light snow to most
elevations north of Flathead Lake during this time, though only
minimal valley impacts due to snow are anticipated. How far south
the cold air advances remains relatively uncertain, with around a
65% chance of reaching as far south as Missoula by late Saturday.
A series of shortwaves will continue to traverse the Northern
Rockies through the weekend, bringing modest snow accumulations to
area mountain passes. As for the valleys, most accumulations
through this weekend will likely occur during the overnight and
early morning hours. Current projections have around 4 inches of
snow accumulating during a 72hr period Friday through Sunday for
the valleys north of I-90. While snow is likely to fall for area
valleys south of the Interstate, accumulations are much more
uncertain at this time. The mountains and mountain passes are more
likely to see accumulating snow, with a 70% chance for 6 inches
or more during the same period.
More seasonable temperatures and unsettled weather conditions will
persist into early next week.
&&
.AVIATION...VFR conditions will occur at all terminals through
20/1200z. KGPI will begin to receive a northeasterly wind to 10
knots this afternoon.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&
$$