281
FXUS65 KMSO 161020
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
420 AM MDT Tue Jul 16 2024

.DISCUSSION...Early this morning, an air quality sensor in Clinton
showed unhealthy readings. This was likely due to wildfire smoke
originating from the Miller Peak fire, located approximately 7
miles to the west. Also, the Butte area has fluctuated between
unhealthy to unhealthy for sensitive groups. Latest near surface
smoke projections depict smoke from the Miller Peak fire to not
only impact southwest Montana again tonight, but light easterly
winds could push the smoke into the Bitterroot Valley and/or
Missoula Valley later tonight and also Wednesday night.

We continue to carry a very slight chance for showers in Glacier
National Park later today. If a shower or weak thunderstorm is
able to form, it would mostly likely be over the Divide and points
east. The water vapor imagery this morning would suggest that
there may be too much dry air on the west side of the Divide to be
able to allow for any clouds to gain any vertical structure. Water
vapor satellite also depicts a weak upper wave east of Portland,
Oregon. This system is mostly dry, and as it moves over northern
Idaho this afternoon, it will likely bring high clouds.

On Wednesday, an upper level trough (currently located offshore of
northern California) will rotate clockwise around the warm upper
ridge in place over the Northern Rockies. Models suggest it will
be over the Canadian border by Thursday morning and then track
southeast towards South Dakota by Friday morning. This feature
could bring enough lift and moisture that scattered showers and
thunderstorms are possible, generally a 15 to 20 percent chance
Wednesday afternoon and evening. There is a 15 percent chance for
nocturnal dry thunderstorms across northwest Montana Wednesday
night. Main impacts from these showers could be outflow winds of
35 to 45 mph, and lightning.

As if it hasn`t been hot enough, we continue to anticipate another
period of 90 to 100 degree temperatures into this weekend. While lower
valleys of Idaho could range from 100 to 110 degrees, the western
Montana valleys could range from 90 to 104 through Monday July 22. For
heat safety tips, please check out weather.gov/heat for more
details.

There continues to be a chance for a ridge breakdown in the
ensembles for next week. There seems to be a little bit of delay
in the clusters and this may not occur until Tuesday or Wednesday
(July 24). As mentioned previously, this type of pattern could
bring increased winds, thunderstorms and new fire starts.


&&

.AVIATION...Hot and dry conditions are expected today with a only
few showers/thunderstorms in the Glacier Region later in the day.
Additionally, smoke from regional and local wildfires will create
hazy skies at times with localized visibility reductions.

&&

.CLIMATE...The Northern Rockies has been in the oven so-to-speak
since the 4th of July weekend. Many locations have been above 90
degrees, consecutively for over a week. If clouds or smoke don`t
mess up the forecast, there could be another full week of 90s for
the region! Kalispell has had 8 days of 90 or greater and could be
in the top 5 for longest stretch. The longest for Kalispell was 13
days ending July 23 of 1960 (records started in 1899). Missoula
has had 9 consecutive days of 90 or greater...by Tuesday of next
week, if smoke from nearby fires don`t keep us cooler, it could be
tied with 17 days with August 23rd of 2022. The longest run was 22
days ending July 18 of 2021. (records began in 1893). While Butte
has had slightly cooler days, it saw 5 consecutive days of 90
degrees ending July 13 of this year. That ranks as 11th longest
run and ties what occurred in 2007. Other COOP stations were
unavailable as of this morning to give comparisons with
climatology. Other impressive temperatures to note include: Our
COOP located in Riggins, Idaho reported a high of 104 degrees
this past Saturday, July 13...this is the 4th time this year this
station has been 100 degrees or greater.



&&

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

$$