Western US states were bracing for yet more torrid weather Friday and into the weekend as so-called atmospheric rivers lined up to dump heavy rain and snow across the already soaked region.
California has been battered by weeks of downpours that have killed at least 19 people, flooding communities, toppling power lines and threatening deadly mudslides.
Forecasters now say the first of two cyclones churning in the Pacific Ocean and bearing down on the west coast will spread the rain further north, forming a band from northern California to the states of Oregon and Washington.
“The most impactful precipitation will remain focused along the coasts of northern California and the Pacific Northwest through Friday night, then precipitation will expand south on Saturday and east on Sunday,” the National Weather Service said in a Thursday statement.
“Northern California has been hammered with heavy precipitation events over the past couple weeks, and any additional rainfall could pose a threat of flash flooding.”
Forecasters said they expect up to six inches (15 centimeters) of rain to fall over 48 hours near Seattle.
Avalanche warnings were in effect for a tranche of Washington state, with the storm bringing wetter, heavier snow into the mountains.
“Dangerous, large avalanches are expected to run naturally during this snowy, wet weather event that will be impacting us Thursday,” the Northwest Avalanche Center (NWAC) said.
So-called “wet slab avalanches” were a particular concern as the wetter snow piles up on top of fluffier, lighter snow, making the snowpack unstable.
“Wet slab avalanches are not something to tiptoe around, and this is a day where it´s a good idea to stay off steep slopes and runouts beneath avalanche paths,” the NWAC said.