Atmospheric river to fuel ‘bomb cyclone’ headed to California this weekend

A powerful storm described as a "bomb cyclone" will be intensified by an atmospheric river over the Pacific Ocean when it hits California this weekend.

"We talk about atmospheric rivers from time to time. About a third of our storms in California have an atmospheric river component. That’s when we tap into that warm, moist air out over the Pacific and it really fuels the rainfall amounts,” KTLA meteorologist Henry DiCarlo said Wednesday.

This “bomb cyclone” (described by the American Meteorological Society as a rapidly intensified storm system) will ride along the atmospheric river and is expected to bring more than a foot of rain to parts of Northern California and 30-foot waves to the Oregon coast.

“This is what we’re looking at Thursday morning. A storm starts to move into the Pacific Northwest and also Northern California,” Henry said. “This overall for the state will be a big storm … but for us here in Southern California we won’t get the direct hit."

The skies over Southern California should remain dry until late Friday or early Saturday but the rain is likely to fizzle in the afternoon.

The second wave on Sunday will be more organized and is expected to bring more widespread rain here in the southern part of the state. “Think of Sunday as the big rain day,” Henry said.

Fortunately, landslides and debris flows don’t look like a significant risk because we aren’t expecting any heavy downpours over short periods, National Weather Service meteorologist Bryan Lewis said. 

The warm air associated with the atmospheric river will also keep snow levels relatively high at around 6,500 feet.

A third chance of showers arrives on Tuesday of next week.