California Welcomes Season’s First Heavy Rain and Sierra Snowfall

California is currently experiencing significant rainfall and the season’s first significant snowfall in the Sierra Nevada. A storm system is advancing southward along the coast, bringing variations in precipitation across the state.

Storm Details and Forecast

As the storm progresses, rain is expected to intensify in some regions, particularly evident in the latest radar updates. The National Weather Service has issued flood watches for several areas in Central and Southern California, including parts of the Los Angeles Basin and the southern Sierra foothills.

Weather Alerts and Warnings

• Flood watches in Central and Southern California.
• Winter storm warnings for the Sierra, notably above 6,000 feet.

Timeline of Rain and Snow

The storm is anticipated to move quickly. Rain will affect Northern California throughout Monday, reaching Southern California by Tuesday morning. Afternoon showers are expected to taper off by Tuesday.

In the Sierra, snowfall will pick up intensity on Tuesday, continuing into the night before subsiding.

Potential Impacts

Rainfall and Flooding Risks

Locally heavy rain, potentially exceeding 1 inch, is possible across California through Tuesday. Specific areas to watch include:

• Foothills of the Sierra below 5,000 feet.
• Southern California’s foothills and high country.

These conditions may lead to flash flooding and minor debris flows, especially in recently burned regions, alongside typical urban flooding on streets and freeway off-ramps.

Snowfall Accumulation

Snow in the Sierra is expected to fall predominantly at elevations above 5,500 feet, with projected accumulations of 1 to 3 feet by late Tuesday night or early Wednesday morning. Some snow may reach lower elevations, including around Lake Tahoe.

Travel conditions over mountain passes like Donner Summit may become treacherous due to heavy snow and strong winds, which could impair visibility. Additionally, the weight of the snow may lead to localized power outages and tree damage.

Looking Ahead: California’s Rainy Season

California’s climate features distinct wet and dry seasons, influenced by the jet stream. Fall marks a transitional phase where occasional Pacific storms can bring rain, particularly to Northern California, with some reaching as far south as Los Angeles and San Diego.

Historically, about 82% of Los Angeles’ annual precipitation occurs between December and March, primarily due to atmospheric rivers associated with strong storms.

Residents are advised to monitor weather updates and consider avoiding travel in affected areas during the storm.