By Mary O’KEEFE

“Atmospheric river” is a term we have been hearing for quite some time and now we have a new term to add to our weather vocabulary – “bomb cyclone.”

According to AP, a bomb cyclone is a term used by “weather enthusiasts” and what meteorologists term “bombogenesis.” That describes a midlatitude cyclone that rapidly intensifies over a 24-hour period. 

“Bombogenesis can happen when a cold air mass collides with a warm air mass, such as air over warm ocean waters,” according to NOAA.

The reason we are hearing about bomb cyclones is because northern California and Washington State just got hit by one. The powerful bomb cyclone hit Washington State last week. It reportedly left two dead and knocked out power to about a half a million customers. The storm brought hurricane force winds, rain and mountain snow to Washington. 

“The extreme weather left widespread damage, blanketed communities in white snow, caused chaos and closures on roads and knocked out power to hundreds of thousands in Washington in what Puget Sound Energy described as a ‘multiple day outage.’ As of 10 a.m. ET Thursday, there are over 320,000 customers without power in Washington,” according to PowerOutage.Us as reported by NBC News.

This cyclone bomb system spanned from British Columbia to northwestern California.

This is a rare weather event; however, it has occurred in the past. In 2018 a large winter storm that spanned from the Carolinas into Nova Scotia hit the East Coast. Meteorologists referred to this system as bombogenesis. 

This type of system also happened in February 2013 when Winter Storm Nemo, which included thunder snow, was reported on Long Island near Cuttyhunk, Massachusetts. Bombogenesis also occurred in the Bering Sea in 2015 and in the northeastern and western U.S. in October 2021. And if you think this is a system that only affects coasts, note that from Oct. 25 to Oct. 27, 2010 there was a bombogenesis over land known as “octobomb” that impacted portions of the Plains and Midwest. All time record low barometric pressure readings were set in Minnesota and Wisconsin by this system, according to weather.com.

And if it weren’t enough for the Pacific Northwest to deal with this current bomb cyclone, it was followed by an atmospheric river. Residents were warned to get ready for the second of this weather one-two punch. 

A NOAA satellite captured enhanced color imagery of a powerful mid-latitude cyclone and accompanying atmospheric river impacting northern California, the Pacific Northwest and British Columbia from Nov. 19 to 24, according to NOAA. 

“The imagery shows the powerful low-pressure system swirling about 300 miles off the coast of Washington as it draws in a strong atmospheric river from across the Pacific Ocean,” according to NOAA.

As of Friday, northern California had seen over 10 inches of rain since the siege began; the Sonoma County Airport in Santa Rosa had seen the city’s heaviest rainfall in 122 years receiving almost 12 inches of rain. In all, there have been more than 100 reports of flooding, landslides and rock slides across northern California in 72 hours ending Friday afternoon, according to the National Weather Service.

Thanksgiving looks to be good weather with highs around 69 degrees. There might be very weak Santa Ana conditions but nothing concerning and no advisories expected, according to NOAA. 

It should be dry through Tuesday with temperatures peaking on Sunday to about 72 degrees. 

Happy Thanksgiving and enjoy the weather!