Winter storm brings rain, mountain snow and dangerous surf to US West

A series of Pacific storms fueled by an atmospheric river is bringing rounds of rain, heavy wet mountain snow, gusty winds and potentially damaging waves to the western United States, with the system expected to keep affecting the region into next week, according to The Weather Channel. The first storm arrived in Northern California on Friday, when KCRA issued an Impact Day because rain, wind and snow were expected to disrupt outdoor activity and travel.

Forecasters say the storms will arrive in waves, each one moving onshore in turn. The timing and totals are subject to change as new model runs come in.

Snow and rain across the West

Palisades Tahoe reported about 10 inches of new snow at mid-mountain and 5 inches at the base from the first storm, slightly below its forecast range at the base. The resort said the system moved through faster than the models had shown, with post-frontal snow showers into early Saturday.

Further storms are expected to bring more snow. The Weather Channel forecast rainfall of 1 to 2 inches for parts of Washington, Oregon and Northern California by Sunday, and 3 to 6 inches in southern Oregon, far Northern California, the northern Sierra Nevada foothills and Washington's Olympic Peninsula by Wednesday. Snowfall in the southern Sierra Nevada could reach 1 to 2 feet by the end of Monday, and totals over 2 feet are possible in the Sierra by the end of the week.

Palisades Tahoe said its latest model runs point to 2 to 3 feet of snow on the mountain from a storm arriving Wednesday, though it cautioned that the forecast could change. Forecasters at the resort noted that the models differ on how long the heavy snow will last.

Travel and road conditions

When enough snow falls, road officials in California put chain controls into effect. Under those controls, the speed limit on Interstate 80 drops to 30 mph and on Highway 50 to 25 mph, according to KCRA. The Weather Channel warned that travel through the Sierra could be very difficult because of heavy snowfall rates, low visibility and strong winds.

Coastal waves and flood risk

Coastal communities face a separate threat from large waves. The Weather Channel said the risk of rip currents and sneaker waves will be higher than average through early in the week, and that the risk of drowning in coastal waters is very high this weekend. The National Weather Service in Medford, Oregon, urged mariners to remain in port during the period of extremely dangerous weather.

The National Weather Service in Portland, Oregon, has said coastal debris, including logs, can become projectiles in cresting waves and has killed and seriously injured people on beaches in the past. Forecasters also warned that high tides combined with elevated water levels linked to El Niño could cause several feet of coastal flooding during the storms.

Inland flooding is not expected from the first strong system, and the rain is largely seen as beneficial after dry conditions. Forecasters warned, however, that later storms could raise the risk of flooding and debris flows, particularly near wildfire burn scars.

What we know so far

The storm sequence is expected to continue through the week, with the next major system forecast to reach Northern California around Wednesday and a cold, snowy pattern to follow. Skies are expected to clear in the Sierra on Saturday before the next storm arrives on Sunday. Residents and travellers in affected areas are advised to monitor local forecasts and road advisories for updates.

Global searches for "winter storm" have risen, reflecting wide public interest in the forecast. Officials have not issued a single consolidated damage or casualty figure for the storm sequence so far.

Palisades Tahoe reported 10 inches at mid-mountain.