The NOAA/WPC 7-day quantitative precipitation (QPF) forecast projects 10-20 in. of rain (and many feet of mountain snow) centered on Northern California. The persistent storm track through the weekend is part of an "atmospheric river" storm track.

A stormy weather pattern develops on the West Coast this week. Heaviest precipitation is on the Northwest Coast early this week shifting the California Coast late this week/weekend. ECM ENS maintains the stormy pattern across California next week.

An intense upper-level low-pressure system southwest of South America is compensated by an upper ridge with two centers either side of South America. In-between high-pressure areas, a low-pressure area over Southwest Brazil causes a streak of heavy rain during the past 30 days across a previous drought zone.

The skill scores during the medium range by primary forecast models indicate ECM ENS is the top model. Recently, ECM extended from 10 to 15 days. Skill scores for ECM will be added for ECM in the 11-15-day period soon. Data is provided by CWG/SVWM.