322
FXUS65 KMSO 221837
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
1237 PM MDT Wed May 22 2024

...HEAVY SNOW IN THE HIGHER TERRAIN ACROSS LEMHI COUNTY INTO
SOUTHWEST MONTANA TONIGHT...

.DISCUSSION...The winter storm for the higher elevations remains
on track from previous forecasts. Confidence has increased in the
details of the impacts enough that we upgraded to winter storm
warnings above 5,000 ft in west central and southwest Montana.
Snow amounts will vary considerably with elevation, but elevations
above 5,000 ft will see significant impacts due to high snow rates
over 1 inch per hour for several hours. Also, where the leaves
have come out on the trees, the heavy, wet snow can cause
significant damage due to snow loading breaking branches, which
may also lead to some power outages.

There will be a break between systems to end the week, though the
region will remain under a cool, showery pattern.

Memorial Day weekend will start off on Saturday with another
cutoff low moving into the region and causing high elevation snow.
All guidance so far is pointing to an overall warmer system with a
little less precipitation. So fewer snow impacts, but an overall
cool and wet start to Memorial Day weekend. Conditions will
generally improve through the weekend with above average
temperatures expected by Monday.

Overall, the pattern remains active next week, but ensembles agree
well on a 2 to 4 day period dominated by a ridge at some point.
There is, however, considerable differences in the timing other
than it will be too late for Memorial Day.

&&

.AVIATION...A cutoff low moving into the northern Rockies region
today is causing widespread rain showers and mountain
obscurations. Snow levels will drop down tonight causing lower
ceilings overnight tonight. Timing is very uncertain, but snow
levels are expected to reach the surface sometime tonight at
terminal KBTM, and will be near the surface there by 23/13Z. Heavy
precipitation, rain at first then snow, is expected at KBTM
between 23/01Z and 23/13Z.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Storm Warning from 6 PM this evening to noon MDT Thursday
     for Bitterroot/Sapphire Mountains...Butte/Blackfoot Region.

ID...Winter Weather Advisory from 6 PM this evening to noon MDT
     Thursday for Eastern Lemhi County...Western Lemhi County.

&&

$$