Western US Daily Snow
By Alan Smith, Meteorologist Posted 3 years ago August 20, 2021
Cool and wet pattern continues for the Northern Rockies
Summary
The Rockies experienced a significant transition to cool and wet conditions this week with much-needed rainfall and even some high elevation snow. Another storm system will impact the Northern Rockies this weekend with additional cool and wet weather expected. Next week's pattern will be much less active with just some isolated showers/thunderstorms for the Rockies.
Short Term Forecast
A fall-like storm system resulted in impressive rainfall across the Rockies this week, and higher elevation areas even picked up some snow on Wednesday and Thursday nights.
Check out the view of a snow-covered Mt. Sopris on Friday morning from Colorado's Roaring Fork Valley.
Our estimated trail conditions for Mt. Sopris picked up on this pattern quite well, estimating snow-covered conditions as of 7am on Friday.
As of Friday afternoon, the storm system that has impacted the Rockies over the past several days (System #1) is exiting the region out onto the Northern Plains with just some lingering light showers over Montana and Wyoming.
However, another storm system (System #2) is approaching from the northwest and will bring another round of wet weather to the Northern Rockies on Saturday. A third system (System #3) will follow on Sunday and Monday, though most of the impacts will be north of the Canadian border.
As the second system arrives, showers and perhaps a few thunderstorms will fill in across the Inland Northwest and Northern Rockies on Friday night and Saturday morning.
Numerous showers and thunderstorms with wetting rains will develop all across the Northern Rockies from Montana to Northern Utah during the day on Saturday with more isolated activity farther south in Colorado.
Temperatures over the next 5 days will be cooler than average for most of the West, except for Arizona, New Mexico, and Eastern Colorado where warmer than average temperatures will return.
Wildfire and Smoke Update
The largest wildfires are currently occurring in California with smaller/less active fires (relatively speaking) farther north. Recent and upcoming wet weather in British Columbia has and will continue to help with the fire situation there.
Smoke on Friday is largely concentrated in California and Western Nevada with more isolated pockets in Oregon and Washington.
On Saturday, smoke from California fires will become entrained into the southwesterly flow around the Northern Rockies storm system – resulting in an increase in smoke across Idaho and Southwest Montana.
From Sunday through Tuesday, California and Western Nevada will continue to be the smokiest areas, with more varying degrees of smoke expected across the Inland Northwest and Northern Rockies due to shifting winds from storm systems passing to the north.
Smoke impacts should be much lower across Colorado and New Mexico, as well as areas west of the Cascades in the Pacific Northwest.
Forecast for Friday, August 20th
Shower activity has been on the decrease across the Rockies since Friday morning, but rain will pick up across northern portions of Washington, Idaho, and Montana as the next system approaches.
The monsoon is largely suppressed south of the Mexico border with only isolated afternoon thunderstorms at best across Arizona.
Forecast for Saturday, August 21st
Widespread showers and thunderstorms with wetting rains can be expected across Idaho, Montana, Wyoming, and Northern Utah with more scattered thunderstorms and lighter rain in Colorado.
The back-to-back wet systems (including the one earlier this week) across the Northern Rockies will significantly reduce the fire danger, which is great news!
Rain will persist into Saturday night across portions of the Rockies and as colder air arrives, another round of high elevation snow can be expected, especially across the Wind Rivers and some of the higher ranges in Wyoming. Snow levels will fall to 10,000 feet or so across this region on Saturday night, possibly lower for some areas.
Forecast for Sunday, August 22nd
Lingering showers will taper off across the Northern Rockies on Sunday morning. The next storm system that approaches will generally affect areas north of the Canadian border, though the Northern Cascades and Glacier National Park could see some shower activity.
Farther south, monsoonal moisture will return across Southern New Mexico and Southeast Arizona with afternoon thunderstorms expected.
Forecast for Monday, August 23rd
Energy associated with the storm system moving across Canada will result in isolated showers and thunderstorms farther south in Montana and Wyoming. Elsewhere, isolated thunderstorms associated with the monsoon can be expected across the Four Corners states.
Forecast for Tuesday, August 24th
Tuesday is shaping up to be a quiet day across the West with just a few lingering showers across the Northern Rockies, and some very isolated afternoon thunderstorms in Colorado and New Mexico.
Extended Forecast
Outlook for Wed, Aug 25th - Sun, Aug 29th
The second half of next week is looking relatively uneventful, compared to recently anyways. A series of weak disturbances can be expected across the Northwest and Northern Rockies, which will result in near to below-average temperatures but only occasional chances for light rain.
Farther south, a weak monsoon pattern is expected across the Four Corners, resulting in near-daily thunderstorm chances across Colorado, New Mexico, Arizona, and Southern Utah, but rainfall should generally be light.
Temperatures will warm back up to above-average levels across the Southwest and Southern Rockies, but no significant heatwaves are anticipated at this time.
Thanks so much for reading! Next update on Monday (8/23).
ALAN SMITH
P.S. Could you take a moment to rate the OpenSummit app with a 5-star review? These reviews help us to be seen by more people, and a larger audience provides the support needed for us to build more features and value for you.
Simply click either link above and scroll down to the section titled 'Ratings & Reviews'.
About Our Forecaster
