Western US Daily Snow
By Alan Smith, Meteorologist Posted 3 years ago August 25, 2021
Cool and showery Northern Rockies, weak monsoon farther south
Summary
An active jet stream over the Northwest and Northern Rockies will result in below average temperatures and light showers late this week. Across the Southern Rockies, a weak monsoon will be in place, resulting in more isolated thunderstorms compared to recent weeks, with the exception being on Thursday when a passing disturbance will support an uptick in thunderstorms across Colorado.
Short Term Forecast
The pattern over the next five days will feature an active jet stream with breezy and showery conditions across portions of Washington, Northern Idaho, and Montana, while more substantial shower activity will occur farther north in British Columbia and Alberta. A weak monsoon in the south will lead to varying degrees of thunderstorm activity across the Four Corners states.
Temperatures over the next five days will generally be below average across the Northwest and above average across the Southwest.
Wildfires and smoke will continue to plague California with smoke transport into Nevada, Southern Oregon, Idaho and Southwest Montana on Wednesday due to southwest winds aloft.
By Thursday morning, an approaching disturbance will begin to push the smoke farther south into Utah with decreasing smoke in Oregon, Idaho, and Montana.
From Friday through Sunday, west/northwest winds aloft will transport most of the California smoke into Nevada, Utah, Colorado, Northern Arizona, and possibly Northern New Mexico. The Northern Rockies should see a break in the smoke during this pattern.
Forecast for Wednesday, August 25th
An approaching disturbance from the northwest should eventually trigger some isolated afternoon and nighttime showers and thunderstorms across the Rockies. A weak monsoon will also maintain the threat for isolated thunderstorms across New Mexico and Eastern Arizona.
Forecast for Thursday, August 26th
Showers and thunderstorms (possible at all hours of the day) will become more numerous across Colorado, New Mexico, Southern Wyoming, and Eastern Utah. Farther north, widespread showers and thunderstorms are also likely across Montana with more isolated/lighter showers in the Northern Cascades and Idaho Panhandle.
Forecast for Friday, August 27th
Another disturbance dropping in from the northwest will bring additional showers to the Northern Cascades Idaho Panhandle, and Montana with more widespread precipitation north of the border. Colder air arriving on Friday night could also result in some light snow across the higher peaks of the Beartooth Range and Glacier National Park.
Farther south, Colorado will see more isolated/less widespread thunderstorms compared to Thursday with a bit more activity expected in New Mexico and Southeast Arizona.
Forecast for Saturday, August 28th
Lingering showers will persist along and east of the Divide in Montana and Northern Wyoming, with snow possibly dusting the higher peaks of the Beartooths and Bighorns. Isolated thunderstorms can be expected once again farther south in Colorado, New Mexico, and Arizona.
Forecast for Sunday, August 29th
Conditions will dry out across the Northern Rockies, while the Four Corners region will remain in a weak monsoon pattern with isolated afternoon thunderstorms and light/spotty rainfall.
Extended Forecast
Outlook for Mon, Aug 30th - Fri, Sept 3rd
Next week's pattern is looking a bit more active across the Central and Southern Rockies as monsoonal moisture increases from the south, possibly aided by tropical activity in the Eastern Pacific. Energy associated with an active jet stream over the northwest will likely interact with this moisture increase to result in an uptick in thunderstorms across the Four Corners states, and perhaps northward into Wyoming.
Despite the increased precipitation chances, temperatures will generally be warmer than average across most of the West next week, except in Montana where temperatures are projected to be near average.
The good news is that average temperatures in late August/early September are cooler than average temperatures in July/early August, and we also aren't expecting any major heatwaves like we have had at times this summer.
Thanks so much for reading! Next update on Friday (8/27).
ALAN SMITH
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