Heavy coastal rains and mountain snow from powerful atmospheric rivers are pouring down the western United States, with more rain likely later this week.
Rain or snow is expected in all 11 western states, with the worst impact projected for California. According to poweroutage.us, 60,000 customers in Oregon and 25,000 customers in California have already lost power due to rain, snow and wind.
Atmospheric rivers — long, narrow regions in the atmosphere that can carry moisture thousands of miles — are the reason flood warnings were issued for more than 7 million people across much of the West Coast, including Seattle and San Francisco.
Flash floods are of greatest concern in the western foothills of the Sierra Nevada and coastal areas through the Southern Oregon Bay Area and into Los Angeles County.
At lower elevations, especially at burn scars, flash floods can be widespread.
Moderate to heavy rain has continued in parts of the Bay Area since Monday night and is expected to continue for several days.
As of Tuesday morning, there were 1.21 inches of rain in downtown San Francisco, 2.72 inches in Santa Rosa, and 4.10 inches in Mount Tamalpais.
The National Weather Service issued a flood advisory as law enforcement reported flooding on the roads.
The storm will drop temperatures in Southern California by 15 to 20 degrees.
Los Angeles National Weather Service Say Goodbye to Warmth murmured Monday. “Temperatures will drop significantly from today to tomorrow (Tuesday). A 15-20 degree cooler is expected due to the approaching storm system.”
Temperatures could drop as low as 49 degrees Celsius in Los Angeles on Wednesday night, according to the Bureau of Meteorology.
Areas west of Portland have seen up to 6 inches of rain in the past 24 hours, with the city setting a daily record on Monday.
Portland recorded 2.12 inches of rain, breaking the old record of 1.08 inches set on December 26, 1996.
Over the next five days, most of the western part of the country will receive 2 to 4 inches of precipitation, with isolated pockets of up to 6 inches. Along the coast, 4 to 6 inches of precipitation is forecast, with isolated areas likely to be higher.
In terms of snowfall, winter storm warnings have been issued for 11 western states.
Over the next five days, lower elevations will see 2 to 10 inches of snowfall, with isolated areas likely to see 12 to 24 inches.
Snowfall at high altitudes ranges from 1 to 3 feet, and in isolated areas exceeds 3 feet.
The good news is that California is off to a fast start with snow cover, an important source of water, and some improvement in drought conditions. According to the California Department of Water Resources, as of the end of last week, the state’s snow cover was over 150% of normal.
Stronger winds are a concern Tuesday, especially near the coast and in higher elevations. In 12 states, he has over 15 million people with storm warnings.
Strong winds in Portland could topple trees weakened by recent extreme weather, dendrologist Colin Bourgeois told CNN affiliate KATU.
“The consecutive dry summers we’ve experienced, especially heat events like heat domes, have caused a lot of damage to trees, requiring a lot of energy to fuel their immune systems to fight off pathogens. consume,” said Bourgeois.