Atmospheric river will impact California and the West late this week

An atmospheric river involving a plume of subtropical moisture will take aim at the West late this week, resulting in heavy, wet snow across the higher elevations of the Sierra and the Rockies, while lower elevations will see rain with possible flooding concerns in areas of California where heavy rain falls on top of deep snow cover.

Ski resorts in the Rockies will also see heavy, dense snow along with strong winds. The Pacific Northwest will be best-situated thanks to a cold airmass in place which should keep snow levels low through the weekend before rising early next week.

Forecast for Wed, Mar 8 – Thu, Mar 9:

A weaker but colder storm will move across the Sierra, Cascades, and Rockies on Wednesday-Wednesday night with light snow expected for most areas. A stronger storm involving subtropical moisture will reach the Sierra Nevada Range on Thursday and a significant warm-up will get underway, resulting in rising snow levels and rain for lower elevation areas. 

A cool and unsettled pattern will linger across New York, New England, and Quebec during this period with additional light to moderate snow showers expected.

Forecast for Fri, Mar 10 – Sat, Mar 11:

The fire hose of Pacific moisture will take aim at the West during this period with heavy snow across the higher elevations of the Sierra and the Rockies. The Cascades will also see heavy snow with lower snow levels expected as a colder airmass remains in place. Light to moderate snow will also extend into Southern BC and Alberta. 

A storm will also move across the Midwest and into the East with snow expected across the Lower Great Lakes as well as the Mid-Atlantic, while Southern New England looks to be right on the edge with uncertainty as to how for north or south the storm will track. 

Forecast for Sun, Mar 12 – Mon, Mar 13:

A weak storm will move across the Sierra and the Southern/Central Rockies on Sunday, then another atmospheric river event with high snow levels is expected to impact the Sierra again starting on Monday. Moisture will also reach the Pacific Northwest and BC on Sunday and Monday with rising snow levels also expected. 

A storm is also projected to move across the Midwest and the East during this period with snow possible for the Great Lakes, Mid-Atlantic, and New England. 

Outlook for Tue, Mar 14 – Sat, Mar 18:

An active pattern will continue from coast to coast with frequent storms expected. The Sierra, PNW, Rockies, and New England all have the potential to see significant snow at some point during this period. Temperatures will generally be cooler than average as well, though keep in mind that "average" temperatures in mid-March are much warmer compared to mid-winter.

Thanks so much for reading! Next update on Friday (March 10).

ALAN SMITH