A storm system swollen with moisture from an atmospheric river will bring rain to Southern California this afternoon, prompting the National Weather Service to issue a flash flood watch for all burn areas in Los Angeles, Ventura and Santa Barbara counties.

In Long Beach, rain isn’t expected until after 4 p.m. today, but the system could bring thunderstorms overnight and into Wednesday and Thursday, according to the NWS.

Peak rainfall rates are expected to range between a half-inch and 0.80 inches per hour in Los Angeles County, forecasters said. The flash flood watch will be in effect from 6 p.m. Tuesday until 11 a.m. Wednesday.

The possibility for showers will persist through Friday, according to the NWS. Dry weather is expected Saturday, and showers are again possible Sunday through Monday.

Rainfall totals across L.A. county should be generally 0.75 to 1.5 inches in coastal and valley areas, and 1.5 to 3 inches in the foothills and mountains.