Western US Daily Snow
By Alan Smith, Meteorologist Posted 3 years ago August 18, 2021
Cool and wet pattern for the Rockies
Summary
A fall-like storm system will impact the Rockies over the next 2-3 days with significant rainfall and below-average temperatures. Strong thunderstorms and flash flooding will be possible across portions of Utah, Wyoming, and Colorado, and peak baggers should expect snow across some of the higher peaks. Two more systems will arrive this weekend with more unsettled weather for the Northern Rockies.
Short Term Forecast
A slow-moving low-pressure system is setting up over the Great Basin. Downstream of this system, significant weather impacts can be expected across the Rockies over the next 2-3 days from Montana to Arizona.
Check out the forecast radar for Wednesday afternoon, which projects widespread showers and thunderstorms and locally heavy rain throughout the Central Rockies.
As this main system exits toward the end of the week, a second system will impact the Northern Rockies on Saturday and into early Sunday. A third system will take a more northerly path on late Saturday and into Sunday with heavy precipitation in BC and Alberta and lighter precipitation across the Northern Cascades and Northern U.S. Rockies.
Temperatures over the next 5 days will be below-average for a change across most of the West. Enjoy!
The smoke situation will improve somewhat across most of the West during the second half of the week, except in California where large fires continue to burn. Elsewhere, smoke levels will be more variable.
The projected smoke forecast for Wednesday afternoon shows a bit of smoke entrained in the flow around the low pressure system extending into Utah, Wyoming, and Idaho. This is an example of how smoke conditions will fluctuate significantly in the days to come. Be sure to check our smoke forecast maps (available with an All-Access subscription) for the most up-to-date information.
Forecast for Wednesday, August 18th
Widespread showers and thunderstorms with locally heavy rain will occur throughout the Rockies, with the heaviest rain totals across Utah and Wyoming. Slot canyons and dry washes in Utah will see a significant flash flooding threat.
Forecast for Thursday, August 19th
This will be another wet day across the Rockies with the heaviest rain occurring over Southwest Montana, Wyoming, and Western Colorado. Colder air arriving will result in some high elevation snow (generally above 10k) across the Beartooth, Teton, Wind River, Bighorn, and Uinta Ranges. The higher peaks of Colorado (13k-14k) could potentially see snow as well.
Forecast for Friday, August 20th
The first system will depart on Friday with lingering showers across Northern Wyoming and Southern Montana, and more isolated showers/thunderstorms across the Four Corners states. Meanwhile, shower activity will pick up across Washington, Eastern Oregon, Northern Idaho, and Northwest Montana on Friday afternoon and Friday night as the second system arrives.
Forecast for Saturday, August 21st
Widespread showers and thunderstorms with wetting rains will occur across the Northern Rockies with lighter showers farther west across the Cascades. Thunderstorm activity will be more isolated farther south and east across Colorado.
Forecast for Sunday, August 22nd
Showers will remain possible across Wyoming and Southwest Montana as the second storm system departs on Sunday. The third system will spread heavy precipitation across British Columbia and Alberta on Sunday, with shower activity (amounts uncertain) extending south of the border into northern portions of Washington, Idaho, and Montana.
Further south, look for isolated to scattered thunderstorms across Colorado, New Mexico, and Arizona.
Extended Forecast
Outlook for Mon, Aug 23rd - Fri, Aug 27th
Next week is looking relatively quiet with some lingering showers possible in Montana on Monday followed by dry conditions across the Northwest and Northern Rockies during the remainder of the week as weak high pressure builds over the West.
A weak monsoon will return across the Four Corners region with near-daily chances of thunderstorms across Colorado, New Mexico, and Arizona (and maybe Southern Utah), but significant rainfall is not expected at this time.
After a nice cooldown, temperatures will return to above-average levels across the West next week. If there is a silver lining, we are getting into late August and past the climatological hottest time of year, so hopefully, the worst of the summer heat is behind us.
Thanks so much for reading! Next update on Friday (8/20).
ALAN SMITH
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About Our Forecaster
Alan Smith
Meteorologist
Alan Smith received a B.S. in Meteorology from Metropolitan State University of Denver and has been working in the private sector since 2013. When he’s not watching the weather from the office, Alan loves to spend time outdoors skiing, hiking, and mountain biking, and of course keeping an eye on the sky for weather changes while recreating.
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