662
FXUS65 KMSO 031955
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
155 PM MDT Mon Jun 3 2024

.DISCUSSION...Showers and thunderstorms will continue this evening
as the atmospheric river impacting the region starts to wind down.
This atmospheric river is also bringing a lot of wind with it, and
we`ve observed winds gusting as high as 60 mph upstream in
Spokane, WA. We`ve had wind advisories out for this as it moves
through western Montana, and the stronger winds may blow down
some trees or cause power outages.

By Thursday and Friday, the ridge will have warmed things up to
about 10 degrees above average for this time of year. That means
many of the valleys in western Montana will warm into the low 80s,
with central Idaho low elevation valleys reaching the low 90s on
Thursday. These won`t be totally clear days due to all the
moisture left behind from the current rains. Expect afternoon
cumulus clouds through the end of the week.

The heat continues into the weekend, but there`s quite a bit more
uncertainty. The NBM shows a range of about 8 degrees between the
high end and low end temperature forecasts for Saturday, but the
ECMWF ensemble MOS system has a range over 20 degrees! The main
source of uncertainty in the temperatures comes from uncertainty
in the ensembles on the location of the ridge axis. Some members
with a cooler forecast have a trough coming out of the northeast,
bringing a cooler air mass and pushing the ridge farther to the
west while others have the axis farther east allowing more cloud
cover and thunderstorms to cap the afternoon temperatures.
However, about 75 percent of the models have the ridge axis over
the northern Rockies, which leads to a warmer, drier forecast. In
any case, all of the model solutions are warmer than average for
this time of year.

&&

.AVIATION...An atmospheric river impacting the area today is on
its way out with a trough chasing it. The recent moisture and the
trough combined will provide enough moisture and instability for
convection this afternoon and evening. Fog is also a concern after
this much rain, but brisk southwest winds overnight will keep the
boundary layer mixed enough to prevent fog.


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Wind Advisory until 8 PM MDT this evening for Kootenai/Cabinet
     Region.

     Wind Advisory until 9 PM MDT this evening for Potomac/Seeley
     Lake Region...West Glacier Region.

     Wind Advisory until 9 PM MDT this evening for Flathead/Mission
     Valleys...Lower Clark Fork Region...Missoula/Bitterroot
     Valleys.

     Wind Advisory until 9 PM MDT this evening for
     Bitterroot/Sapphire Mountains.

     Wind Advisory until 9 PM MDT this evening for Butte/Blackfoot
     Region.

ID...Wind Advisory until 4 PM PDT this afternoon for Northern
     Clearwater Mountains...Orofino/Grangeville Region.

&&

$$