By Reginald Stanley. Posted March 9, 2020, 11:55 PM.

A cutoff low is tapping into subtropical moisture west of Southern California tonight, reeling in a large moisture plume and continuing into Tuesday as the cutoff low makes landfall. Thunderstorms are possible Tuesday due to convection.

This slow-moving cutoff low is expected to stall off the coast of Point Conception on Wednesday, continuing our rain chances through Thursday despite the atmospheric river moving to the east by then. Instability associated with the low could bring additional thunderstorms on Thursday, before finally moving eastward on Friday. Precipitation totals from Monday night through Wednesday morning are predicted to amount to between 1 and 1.5 inches in the valleys, and between 0.7 and 1 inch near Riverside. Locally heavier amounts are possible, however according to the National Weather Service, orographic effects will not be significant in the Riverside and San Diego County mountains during this storm. The valleys should expect an additional 0.3 to 0.4 inches between Wednesday afternoon and Friday. Snow levels are predicted to remain high, above 7,000 feet, due to the warm nature of the storm.

This week's rainfall will boost season totals across the region, possibly significantly. Season totals have fallen below average in the region since January, as the most recent significant rains fell back on December 26.