924
FXUS65 KMSO 051943
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
143 PM MDT Fri Jul 5 2024

.DISCUSSION...Satellite imagery this afternoon shows a shortwave
trough spinning east of the Continental Divide just north of the
border, as well as a high amplitude ridge of high pressure with
its axis just off the West Coast. The Northern Rockies is
sandwiched between these two features, experiencing northwesterly
flow aloft. A shortwave trough embedded in the general flow will
move through northwest Montana on Saturday morning, bringing
chances for showers (about 30 percent) to that area through about
noon and chances for thunderstorms (also about 30 percent) along
the Continental Divide on Saturday afternoon. Northwest flow will
persist on Sunday as the ridge over the Pacific approaches the
Northern Rockies. As it does, temperatures will begin to climb.

The ridge axis will become situated over the Pacific Northwest on
Monday. Daytime high temperatures will continue to climb and
overnight low temperatures will stay elevated, providing little
relief at night. The lower Salmon River valley will see triple
digits during the day and only into the upper 60s to low 70s at
night. Temperatures will continue to rise during the week, peaking
around Wednesday in Idaho and Thursday in western Montana. Expect
daytime highs of 105 to 115 for the low valleys of Idaho and 95
to 105 for the valleys of western Montana. While the temperatures
for any individual day will not be record shattering, the
duration of this event is what makes it worthy of attention and
respect, as the heat wave will last for most of the week and into
the following weekend.


&&

.AVIATION... Expect partly cloudy skies across the Northern
Rockies this afternoon and evening. Northwesterly winds gusting to
about 20 kt will grace the terminals at KMSO and KBTM. A
shortwave trough will bring chances of rain showers (about 30
percent) to KGPI in the morning by about 06/1100Z.



&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Heat Advisory from 1 PM Tuesday to midnight MDT Friday night for
     Flathead/Mission Valleys...Kootenai/Cabinet Region...Lower
     Clark Fork Region...Missoula/Bitterroot Valleys.

ID...Heat Advisory from noon Tuesday to 11 PM PDT Friday for Northern
     Clearwater Mountains.

     Excessive Heat Warning from noon Tuesday to 11 PM PDT Friday for
     Orofino/Grangeville Region...Southern Clearwater Mountains.

     Excessive Heat Warning from noon Monday to 11 PM PDT Friday for
     Lower Hells Canyon/Salmon River Region.

&&

$$