US: Adverse weather forecast to continue across California through at least Feb. 21

Severe weather is forecast to continue across California through at least Feb. 21. The heaviest rainfall is likely across coastal central to southern California over the coming days. The severe weather is forecast to persist through at least Feb. 21.

As of late Feb. 18, the US National Weather Service (NWS) has issued winter storm warnings across northern and northeastern California. Flood and flash flood watches and warnings have been issued over the western, central, and southwestern parts of the state. High wind warnings and advisories are in place across parts of the affected area.

The NWS Weather Prediction Center has issued a moderate risk (the second highest level on a four-tier scale) of excessive rainfall over portions of the Santa Lucia and Santa Ynez ranges in central and southern California through early Feb. 19 and over portions of Santa Barbara and Ventura counties in southern California Feb. 19-early Feb. 20. Slight risk of excessive rainfall is in place for northern and central California through early Feb. 19, northern, central, and western California Feb. 19-early Feb. 20, and northern, central, western, and southwestern California Feb. 20-early Feb. 21.

The NWS Storm Prediction Center has issued a slight risk (the second lowest level on a five-tier scale) of severe thunderstorms for portions of the Sacramento Valley in central California into northern California Feb. 19-early Feb. 20. Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.

Authorities in Topanga have issued an evacuation warning across the area affected by the Owens Fire 2023, while authorities in Santa Barbara County have issued an evacuation warning across burn areas and locations near rivers forecast to swell through Feb. 21. Santa Cruz County has opened three emergency shelters through Feb. 21. Reports indicate that 10,000 people across California are without power as of late Feb. 18.

Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed or a lack of stormwater drainage systems. Sites downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where heavy rain has saturated the soil.

Where precipitation falls as snow, strong wind gusts could lead to periods of blowing and drifting snow; decreased visibility is likely in mountainous areas. Sporadic power outages are likely throughout the affected area.

Floodwaters will likely render some bridges, rail networks, or roadways impassable, impacting overland travel in and around the affected area. Flooding in urban areas could also result in significant traffic congestion. Heavy snow will likely make driving hazardous in some areas; authorities could implement temporary road closures or detours in such locations. Mountain passes and tunnels could be closed as a precautionary measure during periods of intense snowfall.

The disruptive weather will likely cause some delays and cancellations at airports in the region. Flooding or snow could block regional rail lines; freight and passenger train delays and cancellations are possible in areas that see heavy rainfall and potential track blockages.