By Max Matza
BBC News, Seattle
California's elite coastal enclave of Montecito has been ordered to evacuate amid a large tempest that has landed astir of the authorities nether flood watch.
Heavy rainfall was lashing the assemblage adjacent Santa Barbara, location to celebrities specified arsenic the Duke and Duchess of Sussex - Harry and Meghan - and Oprah Winfrey.
Forecasters are informing residents crossed authorities to brace for a "relentless parade of cyclones" implicit the adjacent week.
The deluge has already claimed 12 lives and near thousands without power.
More than 100,000 radical were inactive without powerfulness arsenic of Monday afternoon.
Around 90% of Californians - immoderate 34 cardinal radical successful the astir populous US authorities - were nether flood watch, according to the National Oceanic and Atmospheric Administration.
"We expect to spot the worst of it inactive up of us," Governor Gavin Newsom said astatine a quality conference. "Don't trial fate."
An bid issued connected Monday day by the Montecito Fire Department directed residents of the municipality and adjacent canyons: "Leave now!"
Santa Barbara County Sheriff Bill Brown said that the determination to bid an evacuation was "based connected the continuing precocious complaint of rainfall with nary denotation that that is going to alteration earlier nightfall". Residents incapable to fly are being told to determination to their innermost country oregon precocious ground.
It is unclear if Prince Harry, who is presently promoting his memoir Spare, oregon his woman are presently successful Montecito.
The governor's informing came connected the 5th day of a mudslide successful Montecito that killed 23 radical and destroyed much than 100 homes.
This caller circular of terrible upwind volition bring dense rainfall connected already flooded rivers, damaging winds that are expected to topple trees and powerfulness lines, and dense snowfall successful north-east California.
The US National Weather Service (NWS) reported that up to 8in (20cm) of rainfall had already fallen implicit 12 hours successful the region.
The NWS forecast the heaviest and astir wide rainfall to deed astir Tuesday greeting and afternoon. The bureau has issued a flood informing successful areas astir Los Angeles, including Orange County and the San Bernardino County Mountains.
Other evacuations person been ordered by officials, including successful areas downstream of reservoirs that could overflow.
The Sacramento Valley is besides nether a flood advisory. Schools successful and astir Sacramento person cancelled classes connected Monday.
US President Joe Biden declared a authorities of exigency for California connected Monday, which allows the Federal Emergency Management Agency (Fema) to supply catastrophe relief.
What are atmospheric rivers and weaponry cyclones?
In the past week, California has experienced 2 overlapping upwind phenomena - an atmospheric river, wherever an airborne watercourse of dense moisture flows successful from the ocean, and a weaponry cyclone, a tempest with a accelerated driblet successful unit that creates an explosive effect.
Atmospheric rivers tin origin utmost rainfall and floods. Bomb cyclones necessitate a premix of precocious and debased temperatures, rising and dropping aerial pressure, and moisture, often resulting successful beardown winds and terrible storms.
Last week's storms inflicted wide harm successful bluish California and dumped record-breaking rain.
The tempest damaged homes and businesses, and killed astatine slightest 12 people. Among the victims was a toddler who died aft a redwood histrion fell connected a mobile home.
A pistillate who lived successful a stateless encampment on the Sacramento River besides died connected Saturday erstwhile a histrion subdivision fell connected her tent.
Much of the country deed by dense rainfall has been nether utmost drought conditions. Last year, California capped connected however overmuch h2o residents tin usage successful an effort to conserve its depleting supply.
Despite the rain, overmuch of the authorities remains nether mean to utmost drought warnings, according to the US Drought Monitor.
Experts person said that it would instrumentality galore years of rainfall to reverse the two-decade drought that has deed the occidental US.