US: Large waves and coastal flooding likely to impact parts of West Coast and Hawaii through Dec. 31

Large waves and coastal flooding are forecast to impact parts of the West Coast of the contiguous US and Hawaii through at least Dec. 31. Coastal flooding had already been reported in some areas along the California coast as of Dec. 28, and authorities accordingly called on residents to evacuate some coastal areas in Marin County and Santa Cruz County. In Marin County, officials ordered residents in the Stinson Beach area to evacuate, including those in Calles Pinos, Pradero, Sierra, Onda Resaca, Ribera, and Embarcadero, as well as parts of Calle del Arroyo. In Santa Cruz County, authorities issued evacuation warnings for Capitola Village, the Pajaro Dunes area, and coastal areas near Seacliff State Beach. The coastal flooding has also prompted officials to close some roads in affected areas, including in Santa Cruz County and Monterey County. Transport disruptions are likely in areas that are subject to road closures. Coastal flooding may impact other communities along the West Coast and in Hawaii over the coming days and prompt local authorities to issue additional evacuation orders and road closures.

As of around 13:15 PST Dec. 28, the US National Weather Service had issued the following coastal flood and high surf warnings and advisories for the West Coast of the contiguous US and Hawaii:

California

Coastal Flood Warning: Coastal North Bay, including Point Reyes National Seashore; Northern Monterey Bay; San Francisco; San Francisco Peninsula coast; Southern Monterey Bay; Big Sur coast; San Luis Obispo County beaches; Santa Barbara County Central Coast beaches; Ventura County beaches

Coastal Flood Advisory: Catalina and Santa Barbara islands; Los Angeles County beaches; Malibu coast; Santa Barbara County southeastern and southwestern coasts; San Diego County coastal areas; Orange County coastal areas

High Surf Warning: Coastal Del Norte County; Mendocino County coast; southwestern and northern Humboldt County coasts; coastal North Bay, including Point Reyes National Seashore; northern Monterey Bay; San Francisco; San Francisco Peninsula coast; southern Monterey Bay; Big Sur coast; San Luis Obispo County beaches; Santa Barbara County Central Coast beaches; Ventura County beaches; San Diego County coastal areas

High Surf Advisory: Catalina and Santa Barbara islands; Los Angeles County beaches; Malibu coast; Santa Barbara County southeastern and southwestern coasts; Orange County coastal areas

Hawaii

High Surf Warning: Kauai North; Maui Central Valley North; Maui Windward West; Molokai North; Molokai West; Molokai Windward; Niihau; Oahu North Shore; Waianae Coast; Windward Haleakala

Oregon

High Surf Warning: Curry County coast; south-central Oregon coast

High Surf Advisory: Central Oregon coast; north Oregon coast

Washington

High Surf Advisory: Central Coast; North Coast; south Washington coast

Authorities may extend, rescind, or otherwise modify the weather warnings and advisories over the coming days.

Flooding is particularly likely in low-lying communities in coastal areas and coastal communities with easily overwhelmed drainage systems. Disruptions to electricity, water supply, and telecommunications services are possible where significant flooding impacts utility networks.

Floodwaters and debris flows may render additional bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close further low-lying routes that become inundated by floodwaters. Flooding could block regional rail lines; freight and passenger train delays and cancellations are likely in areas that experience track inundation. Flight disruptions, including delays and cancellations, may impact airports in coastal areas that experience flooding.

Localized business disruptions may occur in low-lying areas; some businesses might not operate at full capacity because of flood damage to facilities, evacuations, or some employees' inability to reach work sites.