This year has been one for the books when it comes to severe weather. There have been 18 named storms in 2024 including five major hurricanes that reached Category 3 or greater and the atmosphere isn’t done yet. Two severe weather events, a bomb cyclone and an atmospheric river, are forecasted to hit the U.S. Northwest coast between Thursday and Sunday. The intense rain and winds are predicted to cause widespread power outages and dangerous flooding for residents in California and the Pacific Northwest. Read to learn more about the forecast and watch the satellite imagery video above depicting the rotating incoming bomb cyclone.
Bomb cyclone and atmospheric river to hit the coast of California this weekend
A “bomb cyclone” intensified by an atmospheric river is predicted to hit the Pacific Northwest coast of California this weekend.
“About a third of our storms in California have an atmospheric river component,” said KTLA meteorologist Henry DiCarlo about the interaction between the incoming bomb cyclone and atmospheric river. “That’s when we tap into that warm, moist air out over the Pacific and it really fuels the rainfall amounts,”
Those amounts could reach more than a foot of rainfall according to the National Weather Service’s flood watch issued for Marin, Napa, and Sonoma counties until 4 a.m. Saturday.
The National Weather Service also issued a wind advisory for the North Bay, San Francisco Bayshore, and Pacific coast through early Thursday, along with a high surf advisory from Wednesday to Friday, warning of waves up to 22 feet.
This forecast follows in the footsteps of the “historically strong bomb cyclone,” that hit the Pacific Northwest and Canada’s British Columbia earlier this week.
The storms left more than 500,000 Washingtonian home and business owners without power early Wednesday morning and claimed the life of at least one person.
What is a bomb cyclone?
A bomb cyclone is a powerful, rapidly intensifying storm that, due to its sharp drop in air pressure, leads to strong winds, heavy rain and other forms of severe weather.
The name was inspired by how quickly the storm drops in air pressure (i.e. it “bombs out” almost instantaneously).
When a bomb cyclone—dangerous enough on its own—interacts with the concentrated band of moisture-laden air known as an atmospheric river, the already intense storm conditions worsen.
A natural part of the water cycle in the western United States, atmospheric rivers are common in California, Oregon, and Washington.
What area will be most affected by the bomb cyclone and atmospheric river?
According to the National Weather Service’s San Francisco area forecast discussion, the bomb cyclone will be a “major event for the North Bay.”
Rain totals are predicted to be highest in the North Bay and other low-lying areas with a 10% chance of exceeding 12″ by the end of the weekend.
