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000
FXUS65 KMSO 151851
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
1251 PM MDT Mon Apr 15 2024

.DISCUSSION...Gusty westerly winds will be the most noticeable impact the rest
of today through much of Tuesday. Gusts of 20-30 mph will be
common in the valleys. Watch for choppy conditions on area lakes,
particularly Flathead Lake. Temperatures will continue to trend
downward with highs on Tuesday about 10-15 degrees cooler than
today. Scattered showers are also expected on Tuesday afternoon
due to colder temperatures aloft.

An upper trough drops into the Northern Rockies on Tuesday night along with
a backdoor cold front coming across the Divide. A band of snow will
accompany the backdoor front reaching Marias Pass early in the evening then
spreading across the rest of western Montana into Wednesday morning.
Scattered showers will also occur in north-central Idaho with snow levels
near valley floors early Wednesday. Median snow amounts generally range
from an inch or less for valleys, then 2 to 5 inches along the Divide. Road
impacts should be mostly limited to occasional snow cover for area passes,
particularly along the Divide. Warm ground temperatures in valleys should
keep any minor snow accumulations to non-paved surfaces. One area that
could be an exception is the higher valleys of Southwest Montana, where
some road impacts may occur Wednesday morning. Scattered showers will
continue areawide Wednesday afternoon into Thursday morning as the trough
lingers.

By Thursday and Friday, a milder ridge will build over the Pacific
coast into Washington and Oregon. This will present lower pressure
due to the milder conditions there, but meanwhile, colder high
pressure over central Montana will set up a moderately strong
north to east wind gradient over Idaho and western Montana. This
may need to be watched as gusty east winds could be an impact to
area lakes. There is a 20 to 30 percent chance for lingering
mountain snow showers on Thursday.

Models diverge for next weekend (Apr 14-15)...so we look to the
ensemble cluster analysis to see if there are any insights.
Setting the stage leading up the weekend, a temporary high-
latitude omega blocking pattern sets up(which is part of the
reason why the cold trough stays with us for about 4 days)and
models have different takes on how the energy pinwheeling around
the next northeastern Pacific trough will evolve. Around 70% of
the ensemble members depict that energy moving over the region by
Sunday which would bring unsettled and cooler weather for us. In
fact, the NBM forecast ramps up the chance for precipitation for
us. But to be fair, the other 30% of the members (which is still a
plausible outcome), depict a milder and dry ridge over us
followed by a cooler trough into the following week. Let`s hope
that after this chilly week, that the milder pattern will come to
fruition!


&&

.AVIATION...Breezy westerly winds of 15 to 25 kts continue to be
the main story through Tuesday. A few lingering showers continue
into tonight with occasional mountain obscuration otherwise VFR
conditions will be common. Scattered instability showers pick up
again on Tuesday afternoon.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory from 6 PM Tuesday to 6 AM MDT Wednesday
     for West Glacier Region.

     Lake Wind Advisory until 9 PM MDT this evening for
     Flathead/Mission Valleys.

ID...None.
&&

$$