Northern California is in for a rare weather event following what has already been a historic winter season. This specific storm likely won’t drop 10 feet of snow on the mountains or create flood issues in the valley. The storm, which is forecast to hit Tuesday through Wednesday, has been classified as a bombogenisis or “bomb cyclone,” meaning we’re in for a wild ride.
Models are starting to converge on a bomb cyclone making landfall near the Bay Area tomorrow as California gets hit by yet another significant storm.— Colin McCarthy (@US_Stormwatch) March 21, 2023
Widespread heavy rain, flooding, damaging winds, and heavy mountain snowfall is likely, especially for Central CA/SoCal. pic.twitter.com/7RfNTnD3u6
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 something that isn’t seen in this area regularly.
According to the NOAA, fourteen of 20 hurricane-force wind events underwent bombogenesis in the North Atlantic during the first two months of 2014. To be classified as a weather bomb, or having undergone bombogenesis or “bombing out,” the central pressure of a low-pressure system must drop at least 24 millibars within 24 hours.
Current radar imagery actually gives an even better sense of the "Fujiwhara Effect" interaction between two similarly sized low pressure centers near the SF Bay Area rotating around a common center! #CAwx pic.twitter.com/B3Fx0A8vgE— Daniel Swain (@Weather_West) March 21, 2023
So what does this mean for California? For this storm in particular, we’re going to see some heavy winds throughout the region, with up to 50 mph gusts seen in the Bay Area. This is sure to cause some downed trees and power outages throughout NorCal.
For the first time this year, it seems like this storm won’t be bad for flooding and hefty snowfall, but it will be intense. Stay safe out there.