CNN
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A powerful “bomb cyclone” combined with an atmospheric river will unleash more than a month’s worth of rain, hurricane-force winds and feet of mountain snow to parts of the Pacific Northwest and Northern California.

A storm system off the Pacific Northwest coast is expected to rapidly intensify Tuesday in a phenomenon called “bomb genesis,” earning it the nickname “bomb cyclone.” The explosion will become so intense so quickly that it could become a “triple bomb,” tripling the criteria needed to be considered a bomb cyclone, the National Weather Service in San Francisco said.

Bomb cyclones are formidable, dumping heavy snow and strong winds in winter. Due to its location, this could be one of the strongest ever, a storm that only occurs “about once every ten years” and will produce “some of the strongest winds we have seen in years”, which will produce “very dangerous mountainous cause winds’. seas of 30 to 30 feet,” according to the National Weather Service in Medford, Oregon.

This bomb cyclone will work with an atmospheric river, a long plume of water vapor moving like a river through the atmosphere, to wring out heavy rain and significant mountain snowfall across the Pacific Northwest and Northern California starting Tuesday. The pair will remain stationed along the coast and pound the area in dangerous conditions throughout the week and weekend.

What are atmospheric rivers?

Parts of Northwestern California could see 6 inches or more of rain in 48 hours. More than a month of rain is expected in the northern San Francisco Bay area, especially north of the Golden Gate Bridge, the weather service there said. Rainfall of this magnitude is expected to cause significant urban flooding, road debris flows and river flooding.

Conditions will deteriorate from Tuesday afternoon. A Level 2 of 4 threat of flooding rainfall is in effect for parts of Northwestern California and Southwest Oregon, where 1 to 2 inches of rain could fall, the Weather Prediction Center said.

The heaviest rainfall is expected to begin Wednesday and peak Thursday in northwestern California. According to the WPC, there is a level 3 out of 4 risk of flooding rain on Wednesday and a rare high risk of level 4 out of 4 on Thursday.

It is difficult to overestimate how great these high risks are. They are issued on average on less than 4% of days per year, but are responsible for more than 80% of all flood-related damage and 40% of all flood-related deaths, according to WPC research.

Wednesday will see 1 to 6 inches of rain, with up to 8 inches in some areas. Thursday’s rainfall could match or exceed Wednesday’s totals, especially in the high-risk area.

Heavy snow is expected in higher areas, where winter weather warnings are in place. Blizzard warnings are in effect in parts of the Washington Cascades, where more than a foot of snow falls and gusty winds occur From Tuesday afternoon to Wednesday morning, speeds of up to 100 km/h are possible.

“Traveling can be very difficult to impossible. Strong winds could cause extensive damage to trees and power lines,” the National Weather Service office in Seattle warned.

One to four feet of snow is possible in the Cascades and northern Sierra Nevada Tuesday through Wednesday. Snowfall could create impossible travel conditions on Interstate 5 and highways 31, 36, 66, 89, 97 and 140.

The strong winds will also escalate on Tuesday and peak across the region on Tuesday night. They will be especially strong off the coast and there will be rare hurricane wind warnings have been issued for much of the coastal waters of the Pacific Northwest.

Inland, widespread winds of 35 to 80 km/h are possible with tropical storm force winds up to 120 km/h. Isolated wind gusts at higher elevations and over capes and headlands could reach speeds of 80 miles per hour (or hurricane force).

These powerful winds have the potential to cause widespread power outages and damage to buildings and make travel difficult, especially for high-profile vehicles.

Conditions will start to improve by the weekend, but lighter rain could continue into next week.