Cool and Active Pattern for the West:

A slow-moving storm system will impact the West during the second half of this week, resulting in showers and thunderstorms for the lower elevations and snow for the higher peaks in the Rockies, Sierra, and Cascades. Higher terrain on the east side of the Continental Divide in Wyoming and Montana will see the most snow over the next 5 days. 

Check out the forecast for Beartooth Pass near the Wyoming/Montana border at just under 11,000 feet. We are forecasting up to several inches of snow to accumulate here through Saturday with snow levels ranging from 9,000 to 11,000 feet.

Check out the projected 5-day precipitation totals (rain and liquid-equivalent snow) from Wednesday through Sunday. Rain will be most widespread across the Northwest and Northern Rockies as well as Northern Utah, with more scattered showers and thunderstorms for the Southern Rockies and Southwest. 

Widespread rainfall amounts of over an inch can be expected across the Northern Rockies, especially east of the Divide. 

Temperatures will be cooler than average throughout the Western U.S. over the next 5 days, with milder temperatures (relative to average) in Canada.

Across the East, the Appalachians will experience a drier pattern for the remainder of this week with temperatures running right around average. Areas near the Atlantic Coast will see better odds of rainfall this weekend as a storm system passes just offshore. 

Forecast for Wed (Sep 20) to Thu (Sep 21):

An active pattern can be expected throughout the Western U.S. and Canada with rain showers, thunderstorms, and high-elevation snow. A storm system will also impact the Coast Range in Alaska with heavy snow expected.

The East will stay dry during this period, while the Upper Midwest will be unsettled with showers and thunderstorms expected.

Forecast for Fri (Sep 22) to Sat (Sep 23):

The Central and Northern Rockies will see more rain and high-elevation snow, including locally heavy snow for the Beartooths and Absarokas in Wyoming and Montana. The Southern Rockies will start to dry out overall, though a minor disturbance could bring some rain showers to Northern Arizona and Southern Utah.

Elsewhere, lighter rain showers can be expected in the Pacific Northwest with mountain snow showers developing across portions of Northwest Canada and Southeast Alaska. The Upper Midwest will remain in an active pattern with periods of rain expected near the Great Lakes.

Forecast for Sun (Sep 24) to Mon (Sep 25):

Most of the West will transition into a drier pattern, but a storm system will reach the PNW and Western Canada on Monday with the potential for significant rainfall across the coastal regions. Higher elevations in the Coast Range will receive some snow as well.

More rain can be expected across portions of the Great Lakes, while New England could also see some light rain showers.

Outlook for Tue (Sep 26) to Sat (Sep 30):

An active storm track is expected across the Pacific Northwest, Western Canada, Northern Rockies, and Alaska during this period with periods of rain and high-elevation snow expected. The Central Rockies and Southwest should stay in a warmer and drier pattern.

The East will see better chances of rain during this period compared to the week prior with temperatures running a little above average for late September.

Thanks so much for reading! Next update on Wednesday (September 27).

Alan Smith