A bomb cyclone is merging with a Category 5 "atmospheric River" huge flowing trains of moist atmosphere in the sky, and is dropping lots more precipitation across Northern California.
California is being hit by a "bomb storm cyclone" from the Pacific, which has been dumping heavy rains and snow to several feet. This wild weather could follow a summer of drought and wildfires and could bring flooding, mudslides, and debris flow to the dry and wildfire-ravaged Golden State.
"Bomb cyclone" refers the rapid intensification process called "bombogenesis" which forms them. According to the National Oceanic and Atmospheric Administration, such storms are when the pressure in the center of the storm drops by at least 24 milibars (an atmospheric pressure measurement) within 24 hours.
A Category 5 "atmospheric River" has formed, bringing together giant flowing clouds of moist air from the sky. The potential damage that an atmospheric river can cause, such as hurricanes or tornadoes, is rated. A Category 5 category, which means the strongest, most dangerous, brings the possibility of flooding, gusty winds and mudslides according to the California Department of Water Resources.
On Sunday, October 24, the National Weather Service (NWS), Sacramento, issued several warnings about extreme rainfall, flooding, and debris flows. Rainfall may reach double digits in some areas.
The NWS tweeted that "lots of rain was on the radar this morning" just before 7 AM PDT (10:01 EDT or 1400 GMT). Heavy rain and strong winds are likely for today. Recent burn scars may lead to debris flows and road flooding.
According to The Washington Post, flash flood watches have been put in place for most of Central California and Northern California. Sacramento saw its first rain since March 19, ending an 220-day drought without any precipitation. The region will now receive more than half of a foot of rain.
Near-tornado winds and hurricane-force winds may be experienced in the Pacific Northwest or Northern California. Waves can also be seen crashing onto the shoreline up to 20 feet (6 metres) high.
The Bay Area will be subject to a deluge from Monday to Monday (Oct. 25); Oakland could experience record-breaking water levels in its atmospheric column (known Precipitable WATer Value or PWAT); and the Sierra Nevada mountain range may see 5 to 8 inches (12-20 centimeters) rain.
According to the NWS, flash floods have been reported in areas that were previously subjected to severe wildfires like the Caldor and Dixie fires.
According to the Washington Post, it's not common for a storm to occur so early in the season. This left emergency personnel with little time to plan as they had to fight the wildfires that plagued California for most of 2021.
These fires can also increase the possibility of flooding and mudslides. According to NWS, soil that would normally absorb rainfall can become as water-resistant as pavement after a fire. According to NWS, water that falls downhill can cause erosion, pick up silt, rocks, and ash and burnt vegetation. Once there is regrowth, wildfire burns will begin to heal.
Amy East, a Santa Cruz-based research geologist, said that 2021's burn scars had not had much chance for vegetation recovery because of the timing of the storm. She wrote this email to The Washington Post. "The Dixie Fire continues to smolder, and that area is only showing the beginning of plant growth."
Original publication on Live Science