Weather across America

(NATIONAL) Heavy rain and snow melt will increase flooding concerns across portions of the Pacific Northwest, and above normal temperatures will extend across much of the U.S.

A series of Pacific systems are likely to produce unsettled weather from the Pacific Northwest into the northern Rockies through the early part of the week.  

The system that moved into the region early Sunday will continue to weaken, providing a brief lull before the next system begins to impact the area Sunday night. Associated with an atmospheric river, this next system is forecast to direct a long fetch of deep Pacific moisture into the Northwest -- fueling heavy precipitation across western Washington and northwestern Oregon.  The heaviest precipitation is expected to develop overnight and continue into Monday.  

As snow levels increase, the combination of heavy rain along with melting snow may raise flooding concerns in the coming days across portions of the Northwest.

Elsewhere across the western U.S., high pressure and dry conditions are forecast to continue through the early part of the week.  Temperatures are expected to warm to above average, with offshore winds promoting near-record to record high temperatures across portions of California Monday and Tuesday.

Across the central and eastern U.S., a fast-moving system is expected produce rain changing to snow from eastern North Dakota to the upper Great Lakes Monday, before producing some generally light snow accumulations across the Northeast on Tuesday.  

Meanwhile, a second system is forecast to deliver some additional light snow and mixed precipitation across the northern Great Plains to the upper Great Lakes on Tuesday.  South of the these systems, temperatures are forecast to warm, with above to well-above normal temperatures expanding across the Plains and Midwest into midweek. 

Following a chilly start to the week behind an arctic front dropping south through the Northeast and the Mid Atlantic, temperatures are forecast to moderate on Tuesday and Wednesday across much of the eastern U.S. as well.