California is bracing for a series of new storm systems expected to bring heavy rain, significant snowfall, and strong winds to various parts of the state, following a winter characterized by above-average precipitation in many regions. Forecasters predict potential flooding, mudslides, and hazardous travel conditions as a result of the upcoming weather events, which are expected to intensify from late Sunday through Monday.
Recent Weather Context
California has experienced a notably wet winter, with several areas already reaching or exceeding their average rainfall totals for the entire season. This follows a drier period earlier in 2024 that had contributed to firestorms in January. The current water year, spanning from October 1 to December 31, ranks among the top nine wettest for official climate locations.
Oxnard and Santa Barbara have recorded their wettest starts to the water year. Downtown Los Angeles has received 11.64 inches of rain, approximately 82% of its normal annual rainfall. Sandberg, in northwest Los Angeles County mountains, has recorded over 16 inches of rain, its wettest start to the water year since 1934, exceeding its typical annual average of 13.14 inches.
A previous storm system, which affected the Rose Parade, marked the first such occurrence since 2006 and led to several daily rainfall records being surpassed:
- Oxnard: 1.09 inches (exceeded 0.83 inches from 2006).
- Sanberg: 1.25 inches (exceeded 0.56 inches from 2006).
- Hollywood Burbank Airport: 1.32 inches (exceeded 0.35 inches from 2006).
- Long Beach Airport: 1.11 inches (exceeded 0.60 inches from 1982).
- Lancaster: 0.87 inches (exceeded 0.24 inches from 2006).
Upcoming Storm Systems and Timeline
A powerful storm system is forecasted to move into California this weekend. A cold front from the northwest is projected to reach the Los Angeles area by Saturday, bringing rain and high-elevation snow through Sunday. Rainfall in Los Angeles is anticipated to be less intense than a preceding storm, while the Central Coast expects heavier precipitation. Northern California is also projected to be significantly impacted by this weekend storm, with heavy rain posing risks of urban and roadway flooding, as well as rising rivers and streams.
Southern California will experience warm, dry weather on Thursday and Friday due to an offshore flow before temperatures drop slightly on Saturday. A more substantial change is expected on Sunday night as a significant storm system arrives, bringing potential threats of thunderstorms, flooding, gusty winds, dangerous waves, and mudslides. Heavy rainfall is predicted to continue into Monday, with the most intense period of the storm system projected from late Sunday through Monday. Brief thunderstorms are possible during the storm's peak.
Another colder storm system is predicted to affect the region between Monday and Tuesday, potentially bringing isolated thunderstorms, heavy downpours, hail, and snow levels down to 5,000 feet. Heavy rain bursts, severe thunderstorms, and damaging wind gusts are anticipated through Tuesday. Rainfall is expected to diminish by Tuesday night, with intermittent precipitation.
A temporary break in storm activity is forecast for Wednesday, but rain is expected to resume from Wednesday night through Friday.
Rainfall Projections
- Coastal and Valley Areas: The weekend storm is predicted to bring 1 to 3 inches of rain. On Monday, coastal and valley areas in Southern California are expected to receive 1 to 2 inches.
- Foothills and Mountains: 3 to 6 inches of rain are predicted for foothills and mountains from the weekend storm. Mountainous regions in Southern California could receive twice the amount of rain expected in coastal and valley areas on Monday.
- Rainfall Rates: Rates are estimated between 0.25 to 0.5 inch per hour, with localized rates potentially reaching 1 inch per hour, particularly in Ventura County foothills and mountains.
Snowfall Projections
- Southern California Mountains: Snow levels are expected to remain above 6,500 feet, with a rain-snow mix possible down to 6,000 feet by Sunday night. Forecasts indicate 2 to 6 inches of snow above 7,500 feet, and up to 9 to 12 inches on the highest mountain peaks. Snow levels early in the week are expected to remain above 6,000 feet for most of the storm's duration, with moderate snow accumulations predicted for mountain resorts and possibly lower elevations later in the week.
- Northern California Mountains: The western slope of the Sierra Nevada, northern Shasta County (including portions of Interstate 5), and parts of the state’s Coast Range could receive up to 8 feet (2.4 meters) of snow before late Wednesday. Hazardous travel conditions are anticipated due to heavy snow, wind, and low visibility, with vehicle chains required on Sierra Nevada roads.
Wind Conditions
Gusty winds are expected with the weekend storm. Wind advisories have been issued for higher-elevation areas of Ventura and Santa Barbara county mountains, interior San Luis Obispo County, and the Santa Lucia Mountains, effective from Friday afternoon through Saturday evening and potentially extended to the Central Coast. Wind gusts are anticipated to be strong enough to potentially dislodge trees, especially in the Santa Lucia range, given the already saturated soil conditions from previous storms. The Bay Area is also expected to experience wind gusts over 40 miles per hour in Big Sur and higher terrain areas on Sunday.
Coastal Conditions and Health Advisories
On Friday, king tides in Corte Madera, Marin County, resulted in localized flooding. A high-surf advisory is likely to be issued for Southern California beaches from Monday to Thursday. Wave sets exceeding 10 feet are possible across all Southern California beaches, with a 20% to 30% chance of damaging sets developing from Tuesday night through Wednesday night. The highest waves are predicted for the northwest-facing shores along the Central Coast. The Bay Area's coastline is also preparing for the storm, with a beach hazard warning in effect from Thursday night through Saturday morning, anticipating large waves of 14 to 19 feet and strong rip currents.
The Los Angeles County Department of Public Health has advised the public to avoid ocean water at beaches due to elevated bacteria levels caused by the rain. This advisory is in effect until at least 4 p.m. Monday, with potential for extension.
Potential Hazards and Incidents
The anticipated rainfall and snow increase the threat of additional flooding and mudslides, particularly in areas previously affected by wildfires. Moderate impacts from the storm are expected, including an increase in traffic accidents due to slick and flooded roads, minor mudslides, and minor debris flows.
Recent incidents include:
- Flooding: Thursday's rainfall led to flooding on the 5 Freeway in the San Fernando Valley, necessitating lane closures. In San Diego, a man and his daughter required rescue from a vehicle in rapidly moving water.
- Debris Flows: In Sherman Oaks, heavy rain caused mud and debris to flow down a hillside at a residential construction site; no injuries were reported, though two individuals were evacuated from a nearby home.
- Tree Fall: A large eucalyptus tree fell across the 101 freeway in coastal Santa Barbara County, closing the southbound lanes.
- Other Incidents: In Orange County, a woman's body was recovered from the Santa Ana River in Fountain Valley; the circumstances of her entry into the water were not immediately clear.
Preparedness and Response Efforts
Authorities across California are preparing for the storm's impact. The National Weather Service in Sacramento advised precautions, including packing winter safety kits for travelers. Winter storm warnings are active from southwest Oregon to the Southern California border. California’s Office of Emergency Services has positioned fire and rescue personnel and resources in areas prone to flooding, mud, and debris flows. Pacific Gas & Electric (PG&E) stated it is utilizing artificial intelligence and machine-learning weather models to direct crews and equipment in anticipation of the storm, which is expected to progress in multiple phases.
The Los Angeles County Sheriff's Department and L.A. Fire Department have issued evacuation warnings for burn scar areas of the Palisades and Eaton fires, advising residents to prepare for mud or debris flows and potential evacuation.
Residents in some Los Angeles neighborhoods previously affected by wildfires were under an evacuation warning through Tuesday. Los Angeles Mayor Karen Bass ordered emergency crews and city departments to be prepared for responses.
Long-term Outlook
The rainfall in late 2024 contributed to California's recovery from drought conditions, according to the U.S. Drought Monitor, preceding traditionally wet months. The wet winter conditions offer short-term protection against large fires, though the duration of this protection is dependent on future rainfall patterns. Following this storm cycle, a period of dry weather, potentially lasting up to two weeks, is projected. Meteorologists do not expect this storm system to be as severe as the "Pineapple Express" storm that impacted the region last Christmas.