Weather Insider: Tracking a bomb cyclone and an atmopheric river

A large and unusually strong storm is impacting much of the Pacific Northwest and Northern California. The system is being called a "bomb cyclone". A bomb cyclone is a classification a storm system earns if its pressure drops rapidly. If a (midlatitude) cyclone's pressure falls at least 24 millibars in 24 hours, it can be called a bomb cyclone. The large tail-like feature moving into Northern California and the Pacific Northwest is the atmospheric river.

As of 5:30 PM on Tuesday, Nov. 19, there are a number of winter and wind-related watches, warnings, and advisories in place across the Northwest. The red, pink, and purple areas represent various winner weather/storm advisories. The red area represents a relatively rare blizzard warning for the Cascade Mountains in Washington state. The tan colors represent wind advisories and high wind warnings.

Speaking of blizzards, there are some specific criteria that must be met for a snowstorm to officially be classified as a blizzard. If the winds are at least 35 MPH, visibility is less than a quarter mile, and if it lasts for 3 hours or more, it earns the blizzard classification.

We will continue to track this system and any potential impacts to Southern California in the coming days.