It was a wild weekend in Northern California that saw four feet of snow fall on the mountains and nearly 10 inches of rain cause widespread flooding. Now, another storm is on its way to the region and it might be even crazier than the last one.
Weather radars show a rare “bomb cyclone” storm heading towards the western United States that could bring with it plenty of rain and snow. The storm is expected to reach NorCal on Tuesday and last through Thursday. Here’s a look at the radar over the Pacific Ocean:
A rare U.S. west coast "bomb cyclone" will form Tuesday over the Pacific Ocean.— Ryan Maue (@RyanMaue) January 1, 2023
The storm center will remain well off-shore w/hurricane force winds but an "atmospheric river" or front will lash the coast on Wednesday.
ECMWF 06z (@weathermodels_) pic.twitter.com/HyjN6G9VTz
We hear about atmospheric rivers in the Pacific Ocean all the time, but rarely a “bomb cyclone” or “bombogenesis.” So what the heck is a bomb cyclone? Here is a definition from the National Oceanic and Atmospheric Administration:
Bombogenesis, a popular term used by meteorologists, occurs when a midlatitude cyclone rapidly intensifies, dropping at least 24 millibars over 24 hours. A millibar measures atmospheric pressure. This can happen when a cold air mass collides with a warm air mass, such as air over warm ocean waters. The formation of this rapidly strengthening weather system is a process called bombogenesis, which creates what is known as a bomb cyclone.
In layman’s terms, a bombogenesis is a rapidly intensifying weather system of low pressure that occurs when cold air collides with warm air over the ocean, which strengthens the system. While the weather phenomenon isn’t rare, it’s also not seen in this area regularly.
Northern California had a run-in with a bomb cyclone in November 2019, which brought a few feet of snow to the mountains and heavy rain and wind to the valley. In fact, the storm was so powerful that it broke the record for lowest pressure ever measured in California. The reading occurred in Eureka:
Pressure has bottomed out at around 28.69" at Crescent City, which is (unofficially) the lowest for California since records have been kept.— NWS Eureka (@NWSEureka) November 27, 2019
See for yourself: https://t.co/FcbR5VqPxs https://t.co/ZZ45IPlwJ0 https://t.co/YlpTyKIWQy
The result of a bombogenesis? Typically a storm is intensified when it reaches “bombing out” and includes increased rain, snow, extreme wind, and even lightning. The fact that the NWS used the term means that the storm has intensified significantly over the course of its development.
We are still awaiting final forecasts for the incoming storm in terms of snow and rain totals, but you can be sure it’s going to be a doozy. Heavy snowfall and possible flooding could once again be on the menu for Northern California. Stay safe out there.