• Weekend storms expected to bring some relief
• But if dry weather and Santa Ana winds return, fires could return
Risk of landslides in burned areas is low but still present, forecasters say
Southern California is set for its first real rain of the winter as the Red Flag fire weather warning is finally scheduled to end Friday morning.
However, there are concerns that this weekend’s rain could only provide temporary relief. Dry spells could return after this weekend. It raises serious questions about whether dangerous fires can come back late. One big problem is that Santa Ana’s wind season can last into February and March, and one weekend of modest rainfall could turn into several more weeks of dry wind and weather if it materializes. It’s not comparable.
Southern California is in the throes of a historically dry winter and start to winter. One is a record book with crushed records collected from the late 19th century. And the region is racing ahead with time to catch up on a severe deficit in rainfall before the winter rainy season ends.
“We’re seeing a lot of weather,” said Alex Tardi, a meteorologist at the National Weather Service office in San Diego, which also provides forecasts for Orange County and the Inland Empire. “This was really extreme for Southern California.”
Southern California has been stuck in a punishing weather pattern since October. In January, the weather pattern worsened as the storm’s track was blocked from “southbound Seattle from all of the West, not just Southern California.”
The lack of rain collided with seven Santa Ana wind events in Southern California in January alone, a dangerous combination that dries the air and vegetation and creates fire weather conditions that make the brush especially flammable. I did. There have been a total of 15 Santa Ana events since November, Tardy said.
“Santa Ana winds really took a toll on sucking moisture out of the atmosphere,” Tidy said. “Because the ocean layer was blown out of the sea. The desert came to the coast.”
Concerns about dry start from February to February
After this weekend’s rain, the long-term outlook is for Southern California to “return to a drier pattern that will likely return,” Tardy said.
This is the driest start to the water year, which began on October 1st. Book of records for locations such as San Diego, Orange County, Inland Empire, Los Angeles International Airport, UCLA, Van Nui, Woodland Hills, and Camarillo.
Other spots have the second driest start since October 1, including places like downtown Los Angeles. Highlights of the season – 6.38 inches of rain. The average annual rainfall for downtown is 14.25 inches.
First real rain of winter expected
This weekend’s rain is largely expected to bring a welcome respite from the last few weeks of almost unrelenting fire weather. For 15 of the past 18 days, it has been scheduled to end at 10 a.m. Friday in parts of Southern California.
This week brought a number of new and threatening wildfires to Southern California, including the Hughes Fire, which has burned more than 10,000 acres since Wednesday around Castaitic Lake just north of Santa Clarita. As of late Thursday, the Hughes fire was 36% contained. The 23,400-acre Palisade Fire was 75% contained and the 14,000-acre Eaton Fire was 95% contained.
The rain is expected to break downtown Los Angeles’ record streak of minimal rainfall. Downtown Los Angeles hasn’t seen more than a tenth of an inch of rain in a calendar day since 0.13 inches of rain fell on May 5th. As of Friday, it has been 264 days since downtown L.A. received more than a tenth of an inch of rain. This is a downtown record. The previous mark was 253 consecutive days from February 25, 2008 to November 3, 2008.
At this time, forecasters are expecting widespread rain this weekend. Between Saturday and Monday, Downtown L.A., Long Beach and Santa Clarita could get three-fifths of an inch of rain, while Canoga Park and Fillmore could get more than half an inch of rain and Thousand Oaks, two-fifths of an inch. You can. Of rain.
(National Weather Service)
San Diego, Anaheim, Irvine, San Clemente, Riverside and Lake Elsinore could see 0.7 to 1 inch of rain. San Bernardino, Ont., Temecula, Oceanside, Escondido and Mira Mesa could get 1.5 inches of rain.
(National Weather Service)
But this is a difficult storm system to predict, said Ryan Kittel, a meteorologist with the Weather Service’s Oxnard office, who issues forecasts for Los Angeles, Ventura, Santa Barbara and San Luis Obispo counties. This storm is being fueled by a low pressure system coming south from Canada, and current forecasts place a low pressure system off the coast of Southern California.
If that low-pressure system moves any further west, it could bring more rain than expected. If it wobbles a little to the east, the storm could produce more rain than expected, Kittel said.
A period of rain could begin as early as Saturday morning and last into Monday night. But the best chance for rain will be Saturday night into Sunday, Kittel said for Los Angeles, Ventura, Santa Barbara and San Luis Obispo counties.
The heaviest chance of rain is Sunday and Monday in San Diego, Orange, Riverside and San Bernardino counties.
Risk of thunderstorms and landslides
Most often, the rain that falls is light intensity and spreads out for many hours.
But there is a 10% to 20% chance of thunderstorms across the region, which can occur at any time and can bring isolated short bursts of rain at a rate of half an inch per hour, Kittel said. Ta.
That’s quite a number. This is because it is the starting threshold for recently burned areas to develop debris flow. This is a type of damaging landslide where the water picks up rapidly flowing water, mud, rocks, branches and sometimes huge boulders.
Hillsides are vulnerable to landslides after wildfires because fires repel soil to water, and instead of being absorbed, rain flows downhill and picks up rocks and debris.
Debris flows are deadly. In January 2018, 23 people were killed and at least 130 homes were destroyed when rivers of mud and rocks flowed through coastal Montecito, which had been burned a month earlier by the Thomas Fire.
According to Kittel, there will be several spots throughout the region that will see these thunderstorms this weekend. The question is whether they happen to appear in recently burned areas.
Putting it all together, Kittel said there is a 5% to 10% chance of damaging debris streams in recently burned areas of Los Angeles and Ventura counties from this weekend’s storms.
There is also a moderate risk of small hail.
Snow levels may drop to elevations between 3,500 and 4,500 feet above sea level. Five to 10 inches of snow is possible in the San Gabriel Mountains. Especially on Sunday, the Grapevine section of Interstate 5 could see perhaps an inch of snow, potentially causing highway delays, Kittel said.
(National Weather Service)
Wrightwood and Big Bear Lake could get 8 to 12 inches of snow. This raises the prospect of authorities requiring motorists to put chains on their tires when driving into mountainous areas like Big Bear.
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