Additionally, the bomb cyclone was the most powerful storm on record to strike the region, in terms of minimum central pressure.

[10] In late October 2021, a Pineapple express, an atmospheric river that often affects Western North America, opened into the Pacific Northwest, channeling a series of three powerful cyclones into the region.

[12][13] Afterward, the system curved northward and then north-northwestward, while gradually weakening, before being absorbed into another approaching extratropical cyclone from the west, late on October 22.

[14] This second cyclone also developed into a powerful storm, peaking at 970 millibars (29 inHg) in the Gulf of Alaska; however, the system curved northwestward and stayed out at sea.

[2] Around this time, the system's rainbands began moving ashore in Western North America, bringing severe impacts to the region.

[2] Afterward, the cyclone gradually weakened as it slowly moved towards the coast of British Columbia, with a new low developing over California, as the eastern portion of the system broke off and became a new storm.

[24][25] However, the new storm that broke off from the bomb cyclone continued moving eastward across the United States for the next several days, before developing into a powerful cyclone that struck the Eastern United States around the Halloween weekend, producing 3.01 in (76 mm) of rain in Baltimore, and resulting in the George Washington Parkway shutting down.

[26][27][28][29] In anticipation of the storm's impacts, the National Weather Service (NWS) issued Flash flood watches and warnings across portions of Central California, including the San Francisco Bay Area.

[30] The NWS issued evacuation orders for residents around the Santa Cruz Mountains, due to concerns of debris flows from the burn scar of the CZU Lightning Complex fires in 2020.

[31] In San Francisco, city authorities sent text alerts to residents, warning them of flooded streets and downed trees and power lines.

[1] Rainfall from the storm resulted in flash flooding and mudslides in areas with wildfire burn scars, including a landslide that forced the closure of SR 70 in both directions.

Multiple downed trees were reported in the Portland metropolitan area, and a small outdoor greenhouse was destroyed in Eastwood Elementary School, in Hillsboro.

[1] In Washington state, powerful winds from the bomb cyclone toppled a tree onto a car, killing a mother and her son inside.

[36] Winds from the storm gusting up to 61 mph (98 km/h)[30] resulted in power outages for over 170,000 customers, around the Seattle metropolitan area and around Puget Sound.

[7] On October 23, large waves produced by the storm caused 40 containers on the Zim Kingston cargo ship to be thrown overboard, about 5 miles (8.0 km) off the coast of Victoria, some of which then ignited a chemical fire.