805
FXUS65 KMSO 221839
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
1239 PM MDT Sat Jun 22 2024

.DISCUSSION...A brief weak ridge of high pressure will be the
dominate weather feature over the Northern Rockies this weekend,
allowing for afternoon highs to run 10-15 degrees above normal.
Most valleys in western Montana will top out in the mid to upper
80s and low 90s for the valleys of north-central Idaho. Currently,
there is a 40-50% probability Sunday afternoon temperatures will
reach 90F in the Missoula and Bitterroot Valleys for the first
time this season.

The ridge will breakdown late Sunday afternoon and evening, as a
weak cold front pushes through the region. Isolated showers will
be possible along the front, but the most notable change will be
an increase in westerly wind gusts. Those with plans to recreate
on area lakes, in particular Flathead Lake, can expect a slight
increase in chop, with around a 50% probability for gusts reaching
25 MPH after 3PM.

The ridge quickly rebuilds early next week and very warm
conditions return. High temperatures could be 10 to 15 degrees
above normal by the middle of the week. The normal first 90F
degree day for Missoula is June 18th, if we reach 90F on Wednesday
(26 June) it would be similar to 2022 when our 1st 90F was 27
June. The question is do we have sufficient soil moisture to slow
afternoon warming and delay till July the 1st 90F in Missoula.

A southwesterly flow will develop by the end of the week, that is
expected to open the door for scattered showers and thunderstorms
across western Montana and north-central Idaho Thursday and
Friday. A shortwave trough of low pressure traversing the Rockies
in British Columbia will allow for more coverage of precipitation
over northwestern Montana.

&&

.AVIATION...High pressure over the Northern Rockies will bring
pleasant weather to the region, with primarily terrain driven
winds this afternoon. The ridge will breakdown late in the day
Sunday, that will allow for an increase in westerly winds, up to
25kts for most aviation sites.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

$$