Messy Week Ahead for the Northwest as Bomb Cyclone Moves Ashore

A bomb cyclone is coming together in the Pacific Ocean, gearing up to hit the Northwest and parts of Northern California beginning on Tuesday. Here is a look at what this region can expect out of this powerful storm.

Bomb Cyclone Targets the Pacific Northwest

A major storm system is going to come ashore along the West Coast and drop heavy rain and significant snowfall in a zone from Washington and down into Oregon before creeping into Northern California. The impacts are coming together as an atmospheric river merges with a developing bomb cyclone.

Forecasters are warning that the moisture will be enough to create widespread travel difficulties for much of the Northwest. The high winds will also be enough to bring down power lines and trees, triggering the threat of outages and other challenges.

Meteorologists define a bomb cyclone as a storm that creates a spinning vacuum at various levels in the atmosphere. A storm reaches the official designation of a bomb cyclone when the central pressure falls by 0.71 of an inch of mercury or more in a period of 24 hours or less.

This specific weather maker's central pressure is predicted to plummet from 29.53 inches to a measurement of at least 28.05 inches in just 24 hours. Should this prediction come to fruition, it would more than double the parameters for a bomb cyclone.

The winds will begin to whip up as the storm's central pressure falls. Forecasters are predicting that the most significant boost in power will happen on Tuesday, translating to the highest winds coming ashore at this time. The high winds will impact the Pacific coastline from the south and in areas of the Cascades and Siskyous from the southeast.

How windy will it get? Wind gusts could hit speeds of 90 mph on Tuesday. To put this into perspective, this range puts the winds of the storm at the status of a Category 2 hurricane as defined by the Saffir-Simpson Hurricane Wind scale.

What to Expect for Snow

In addition to the bomb cyclone, the region will also be under the gun for an atmospheric river. This long plume of moisture will soak a large portion of the Pacific Northwest, sending heavy rain across the lower elevations and snow for the higher terrain.

Snow levels will fluctuate throughout the next few days. The snow will first fall across pass levels before rising slightly and then falling back down. This fluctuation in snow levels will be the story for the major mountain ranges in the region, including the northern Sierra Nevada, the Siskyous, and the Cascades.

Up to a foot of snow is possible over the most traveled passes of the Cascades. The strong winds associated with this weather maker will raise the threat of blizzard conditions for some of the most traveled highways.

For instance, Snoqualmie Pass in Washington state is forecast to see 3 to 5 inches of snow on Tuesday night, pairing with winds out of the east-southeast at 10 to 20 mph. Overnight lows will hover right at the freezing level. Another inch of snow is possible on Wednesday before the snow level lifts higher and spares the pass as the temperatures climb into the upper 30s.

However, snow levels will dip again by the weekend with more accumulation possible. After a rain and snow mix on Thursday and Friday, Snoqualmie Pass will see another shot of measurable snow on Saturday night when up to 3 inches is a possibility. Overnight lows will also take a tumble at this time, landing in the upper 20s.