This midweek storm is expected to be moderate in intensity, but another possible storm on the heels of this one could escalate the situation.
“We could very well receive February’s total normal precipitation within the month’s first five days,” forecasters from the National Weather Service’s office in San Diego wrote early Monday morning.
Here’s what to know about the timing.
Monday: A much weaker atmospheric river makes landfall in British Columbia, and some rain falls in the Pacific Northwest.
Tuesday: The more robust storm, which forecasters in Seattle have called “a more substantial atmospheric river system,” arrives late in the Pacific Northwest. With recent heavy rains, stream and river flooding are possible.
Wednesday: The main stream of heavy precipitation is pointed at Northern California. The worst conditions are expected from the northern Bay Area to the Oregan-California border.
Thursday: The bulk of heavy precipitation drifts south into the Los Angeles region, with rainfall arriving in Southern California later in the day.
The slower the storm moves, the more precipitation will fall. As of Monday morning, forecasters believe it will be a quicker-moving storm, easing some of the rain totals that could pile up and lowering the potential risk for flash flooding.
In the beginning, this will be a warmer storm, confining snow levels to higher elevations, but colder air will return as the storm moves through.
There is high confidence that the Sierra will receive over a foot of snow with this storm. The highest peaks are likely to get even three times that amount.