484
FXUS65 KMSO 102020
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
220 PM MDT Wed Jul 10 2024

...Abnormal heat to continue into next week...

.DISCUSSION...High pressure will be the dominant feature over
western Montana and north central Idaho well into next week. Hot
and mostly dry conditions will be the norm. Although current heat
warnings and advisories will drop off tonight when the truly
excessive heat wanes slightly, abnormally hot temperatures will
continue. And in fact, current long range model guidance shows a
70 to 90 percent chance that abnormal heat will continue over the
Northern Rockies Region through the end of July.

The high pressure ridge does flatten slightly tonight into
Thursday, which will mainly lead to an increase in winds,
generally from the southwest to west. This flow will also
transport in some subtle amounts of mid level moisture, which may
produce an isolated thunderstorm near Butte in the late
afternoon/evening.

The upper level flow becomes more southwesterly this weekend,
which will help usher in monsoonal moisture from the desert
southwest. Current model guidance is targeting Sunday into Monday
as the peak timeframe for thunderstorms, mainly across north
central Idaho, Lemhi County and southwest Montana. There is some
indication that moisture could come in a bit further north than
currently depicted, so adjustments to the forecast may be needed.
Storms will initially start out dry with little in the way of
beneficial moisture. Therefore the main concern with storms will
be fire starts from lightning and breezy outflow winds.

&&

.AVIATION...VFR conditions are expected through Thursday. Well
above normal temperatures will continue for all aviation sites
this week. There is around a 70% Probability temperatures will
reach or exceed 100F at KMSO this afternoon. The probabilities are
much lower, around 20%, at KGPI. Smoke from regional wildfires in
Oregon and Washington will further create hazy conditions across
the region through Thursday. Winds will increase aloft on Thursday
and could bring some gusty westerly winds up to 20 kts for all
airfields by Thursday afternoon.


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Heat Advisory until 11 PM MDT this evening for Flathead/Mission
     Valleys...Kootenai/Cabinet Region...Lower Clark Fork
     Region...Missoula/Bitterroot Valleys.

ID...Heat Advisory until 10 PM PDT this evening for Northern
     Clearwater Mountains.

     Excessive Heat Warning until 10 PM PDT this evening for Lower
     Hells Canyon/Salmon River Region...Orofino/Grangeville
     Region...Southern Clearwater Mountains.

&&

$$