Atmospheric major river-arrows to California

A large storm of the atmospheric river – strong enough to potentially compete with some of the extreme storms that have stunned southern California during recent winters – heads towards the coast, lifting the spectrum of damage to damage and floods through the region.

This storm, providing for an attack in the south of California some time before Valentine’s Day, should be the strongest in winter so far, according to the National Weather Service Office in Oxnard.

He threatens to drop large amounts of rain – 2 to 4 inches or more along the coast and in the valleys, from 4 to 8 inches or more in mountains and buttresses – through a strip of Southland. There is 60% chance of precipitation of this magnitude in the counties of Santa Barbara and San Luis Obispo, and 30% of chance in the counties of Los Angeles and Ventura.

There are also extreme fortuitous precipitation, in the sense of the powerful storm of January 9, 2023, which forced the massive evacuation of Montecito and other communities, caused significant floods and resulted in the death of two motorists – including a 5 -man of the year – which was taken in flood waters in the county of San Luis Obispo.

“Certainly, people should be ready to prepare for it to be the humid period we have had this rainy season so far – since the fires have started,” said Ryan Kittell, a meteorologist from the National Weather Service in Oxnard.

“People should really prepare for the worst case,” said Kittell, where high precipitation could send mud and debris sliding off the hills, shaking roads and possibly colliding in houses and others structures.

For the counties of Santa Barbara and San Luis Obispo, the storm could start on Tuesday evening or until Thursday evening, said Kittell. The highest threat should be between Wednesday evening and Thursday evening.

“Admittedly, if you are in a vulnerable area around these burning scars, keep a trace of the weather every day and see how the trend of projections and what seems to be the most likely result in the future,” said Kittell. “Prepare for the worst and hope the best.”

The counties of Santa Barbara and San Luis Obispo could see 12 to 24 hours or more precipitation, precipitation falling at rates between half a pump to an inch or more per hour. Precipitation rates of half a pump or more per hour are able to cause significant debris flows, in which water can pick up mud, rocks, branches and sometimes massive rocks, moving to speeds greater than 35 MPH.

A precipitation rate in this beach “generally causes flooding problems, especially for recent burning areas,” said Kittell. This includes the burning zone of the fire at Lake 2024, which burned 38,664 acres in the mountains of the County of Santa Barbara north of Los Olivos.

While precipitation rates are approaching 1 inch per hour, floods can be triggered anywhere, especially on roads and small streams, Kittell said.

In the scenario of extreme precipitation – which is 20% chance of performing in the counties of Santa Barbara and San Luis Obispo, the forecasters estimate – there could be 4 to 8 inches of rain on the coast and in the valleys.

“Two to 4 inches of rain) will certainly give us problems, but 4 to 8 would be quite extreme,” said Kittell. “And by thinking about some of the projections leading to some of our recent fairly extreme events in recent years, if this is going on, then we are looking at totals that would be very close and approached January 9, 2023.”

The big difference, however, is that Storm was part of a series of powerful systems that hammered California from late December 2022 in mid -January 2023. This season was much dry – one of the most departures dry rainy season in modern California history – “therefore, the impacts will probably be less,” Kittell said.

For the counties of Los Angeles and Ventura, in addition to the 30% chance of large quantities of rain, there is also 50% chance of moderate quantity. The storm could arrive on Wednesday morning or later that Thursday evening. The time for the highest threat is Thursday morning to Friday morning – Valentine’s Day.

A moderate event could cause road floods, but the risk of flow debit would be low, although still present, said Kittell.

Large quantities of precipitation would lead to a “fairly high risk” of producing showers so intense that all recent burning areas in the region are at risk of flow debit, said Kittell.

Recently burned areas are at risk of high rain landslides, because the soil is no longer anchored by healthy vegetation. The heat of the fire makes it more difficult for the soil to absorb water, and the ashes also tend to obstruct the soil, so the water is more likely to flow along the surface rather than to percolate.

The storm should also be strong in the San Joaquin Valley and the foothills of Sierra, potentially affecting trips along the mountain passes in Kern, the meteorological services office in Hanford said.

The storm should be much lower once it reaches the counties of San Diego and Orange and the inner empire, and has a relatively moderate effect in the Sacramento valley. The Sierra Nevada could see 2 feet or more snow, and the areas around the elevation of Lake Tahoe could see “their biggest snow event this season”, according to the Reno meteorological services office.

The San Francisco Bay region could be at moderate flood and damage to trees between Wednesday and Friday, the meteorological service said. The bay region is expected to get its strongest rain between Wednesday at the end of Thursday.

“This will probably lead to flooding problems for urban environments and small flows,” according to the Monterey meteorological services office, which also issues forecasts for the Bay region. “The (US Geological Survey) has also informed us that soil humidity sensors indicate that shallow landslides are likely if rain rates become sufficiently high.”

The next storm follows heavier than expected precipitation from a system that left South California on Friday. For the two -day period which ended at 5 p.m. Friday, Santa Monica obtained 1.26 inch of rain; Beverly Hills, 1.46 inches; Porter ranch, 1.53 inches; Alhambra, 1.64 inches; Downtown la, 1.71 inches; East Pasadena, 2.07 inches; And the Malibu hills, 2.5 inches. The mountains of the Comté de la Vue up to 3.32 inches of rain.

This, combined with the precipitation leading to Valentine’s Day, may be sufficient for southern California to end the “high shots season” and goes to “the weak fire season,” said Kittell, where the Vegetation is wet enough for “the risk for any large fire will be small enough for the rest of winter in the spring. »»

We will need conversations with a number of agencies, including firefighters, before taking this determination, “but we certainly tend in this direction.”

The city center of the has received about 2 inches of rain since the start of the year of water on October 1, almost all since the end of January. The typical average at this stage – halfway halfway from the traditional rainy season – is 7.93 inches. The annual average is 14.25 inches.

Meteorologists said the region needed 2 to 4 inches of rain, widespread, for the end of the shooting season.