Area Forecast Discussion Issued by NWS Missoula, MT
000
FXUS65 KMSO 132021
AFDMSO
Area Forecast Discussion
National Weather Service Missoula MT
221 PM MDT Sat Apr 13 2024
.DISCUSSION...The majority of the Northern Rockies are
experiencing fair weather cumulus clouds popping over the
mountains and this will be the most convection that will be
experienced. The exception is over Lemhi County where a few light
showers are beginning to develop around Gilmore Summit. These
showers will continue to increase slightly in intensity and
coverage while moving northward into southwest Montana. The
convection will diminish after sunset this evening.
A pulse of energy associated with a large low pressure system over
the Great Basin region will make its way up into the Northern
Rockies by Sunday. This disturbance will keep off a few showers
and thunderstorms during the afternoon. North Central Idaho into
West Central Montana have the best chance of experiencing
stronger storms during the afternoon and evening. These storms
have the potential of causing gusty erratic winds along with small
hail.
A low pressure system is still on track to move into the British
Columbia area on Monday causing the pressure gradient to tighten
over the Northern Rockies. This tightened gradient will create
gusty westerly winds, especially over the northwest Montana. The
mountains have a high probability of experiencing wind gusts in
excess of 30 mph. While the broad valleys of northwest Montana
have a 20 to 40 percent chance of gusts greater than 30 mph,
including Flathead lake. These winds will create choppy conditions
during the afternoon and evening on Flathead Lake.
The low pressure system over British Columbia will slide southward
over the Northern Rockies Tuesday into Wednesday causing
significantly colder temperatures. Maximum readings will drop
around 25 degrees compared from Sunday to Tuesday. This system
will also bring widespread precipitation, especially to western
Montana. The precipitation type has the potential to be snow even
down to the valley floors. Snow accumulations are anticipated to
be fairly light with minimal impacts in the valleys, but Glacier
NP and Marias Pass could receive several inches of new snow during
this event.
The models are 50/50 on the ridge building by the latter part of
the workweek, but jump up to around 70% for the ridge being over
the Northern Rockies during the weekend. This will mean a gradual
warming and drying trend of the region.
&&
.AVIATION...The atmosphere is becoming unstable this afternoon as
fair weather cumulus clouds are developing over the mountains.
Southern Lemhi County is beginning to see a few showers develop.
These showers will slightly increase in coverage and intensity
this afternoon as the showers move to the northeast. KSMN will
have vicinity showers until 14/01z. KBTM and KHRF should start to
encounter vicinity showers around 14/00z and last until 14/ 05z.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&
$$