A winter storm is expected to bring much-needed rain and snow to Central and Southern California this week, but also a risk of flash flooding and mudslides, especially in San Luis Obispo and Santa Barbara Counties and areas of Los Angeles County that were burned by wildfires last month.

The robust storm system will swing waves of moisture up and down the California coast, including the already saturated northern part of the state, while also sending moisture inland, adding feet of snow to the Sierra.

The storm will pull in moisture from the subtropics, and the severity of its impacts will depend on where “the bulk of that moisture goes through and how slowly the storm moves,” said Kristan Lund, a meteorologist with the National Weather Service.

“We’re looking at likely seeing the strongest storm of the season and at least so far,” Ms. Lund said.

It’s too early to pin down the forecast with certainty, but as of Monday, the most likely scenario is that rain ahead of the storm will arrive Tuesday night, with rainfall amounts anticipated to be light. After a brief lull of largely dry conditions from Wednesday afternoon, the storm is expected to arrive in San Luis Obispo and Santa Barbara Counties Thursday morning and then head to Ventura and Los Angeles Counties by afternoon.