California – A strong atmospheric river is expected to impact California next week, bringing heavy rain, mountain snow, and potential flooding across large portions of the state, according to federal forecasters.
According to the NOAA National Weather Service Weather Prediction Center, key messages have now been issued for the storm system, which is forecast to arrive from the Pacific and intensify as it moves southward. The atmospheric river is expected to first impact northern and central California, before spreading into southern California later in the week.
Forecast guidance shows the heaviest rainfall focusing on northern and central California through Monday, including coastal regions, the Bay Area, and inland valleys. From Tuesday through Thursday, the storm system is expected to shift south, increasing rain chances for Southern California, including the Los Angeles and San Diego regions.
Forecasters warn that urban flash flooding is possible, particularly in cities, low-lying areas, and locations with poor drainage. Recently burned areas are also at higher risk for mudslides and debris flows, even during shorter periods of intense rainfall.
In addition to heavy rain, high-elevation snow is likely in the Sierra Nevada, where a prolonged snow event could significantly increase snowpack. While beneficial for long-term water supply, the heavy snow may also raise concerns about snow-load impacts, difficult travel conditions, and chain controls along mountain passes.
The unsettled weather pattern may continue through the end of the month, increasing the risk of additional storms and prolonged wet conditions.
Residents are urged to prepare now by clearing storm drains, avoiding flooded roadways, and monitoring updated forecasts and potential flood watches or warnings as the system approaches.
