As the season's most powerful rainstorm will soak in Southern California on Thursday, the first assessment of mudslide danger since the January fire shows that both the Pacific Palisades and Altadna burning areas are in the coming days and several The risk of facing debris flow is significantly higher within the month.

In the San Gabriel Valley, the Eaton Fire burned a deadly and devastating road (more than 9,400 buildings including many houses), and a national report notes heavy rain May cause heavy rain, destructive post-flooding and debris flow.

In West Los Angeles, where the Palisade fire began on January 7, the risk of flooding and rocky landslides was greater than that of debris flow. However, a report released by the California Department of Forestry and Fire and the California Department of Conservation says that in both areas, fires leave huge land in the coming years, including many communities, at risk of additional significant damage.

The report serves as a blueprint for potential damage, not only due to the wet weather this week, but also potentially a future storm.

"Don't take risks," Los Angeles County Supervisor Kathryn Barger said in a news conference Wednesday. "There is an increase in risk in the Foothills community...so please don't let your guard down."

As she spoke, an atmospheric river entered the area, showering gently southward. However, the biggest rainfall is expected to take place on Thursday and brings increased risk of debris flow and flooding, especially in recent burn areas, according to the National Weather Service.

Palisades scar is expected to be subject to 3.35 inches of rain during a three-day storm; Eaton scar, 5.08 inches; and bridge scar is 5.27 inches. But not only does the rain that the area receives can not only make things difficult, but it can also make things worse.

Experts say once rains are raining at a rate of half an inch per hour, the risk of mud and debris rising from burning hillsides increases. According to the Weather Bureau, the worst part of the storm is expected to be between 2 p.m. and 10 p.m. Thursday, with rainfall rates expected between half an inch and 1 inch per hour.

Recently, burned areas have risk of heavy rainfall landslides and the soil is no longer anchored by healthy vegetation. Worse, the heat from fire makes it harder for the soil to absorb water, which can make hillsides susceptible to erosion. This can cause slopes to fall on mud, rocks and dead branches, damaging homes or people on their way.

A heavy rain provides 15 minutes of peak rainfall intensity of 1.57 inches per hour, which will have an 80 to 100 percent chance of producing debris in most Eaton Fire areas, according to data compiled by the U.S. Geological Survey (U.S. Geological Survey). flow.

In Palisades, a storm released 15 minutes of rainfall intensity of 0.94 inches per hour, which would have a 60 to 80 percent chance of following Tuna Canyon Park, Temescal Canyon and Pacific Palisades produce debris flow along Tuna Canyon Park. According to USGS, the risk is higher on the hillside and on the Mandeville Canyon area.

"Floods and debris flows can escalate very quickly," said Ryan Kittell, a meteorologist at Oxnard National Weather Service.

Areas with the highest risk of debris flow and flooding in the Eaton Fire Department include Alzada Drive, located in Alzada Drive, Los Flores, according to Cal Fire report, in Sera Houses downstream of the Madre Dam near the channel, houses in the foothills of the Sierra Madre.

The report says that in Palisades Fire Footprint, above Los Flores Canyon, Pena Canyon, Topanga Canyon, and above Palisades Drive, Temescal Canyon and Rustic Canyon are at risk of debris traffic hazard. For houses located near water sources flowing down from the combustion zone, the risk of flooding increases.

Black Canyon, Carbon Canyon, South of Los Flores Canyon, Piedra Golda Canyon, Tuna Canyon, North of Tusga Canyon, North of Yamanu Canyon, Camino de Yata Above St, St. Inas Canyon, Rivas Canyon, Rivas Canyon, Sullivan Canyon and Palis Canyon, Palis Canyon and Palis Canyon, Palis Canyon and Palis Island, The report states that the debris flow risk in the top community is moderate .

After criticizing Southern California officials for not preparing for the historic fire, Los Angeles County authorities said they have been working to reduce the risk of flood effects.

The crew members were eager to clean up 154 ​​basins, aiming to capture dirt, rock and other debris to pour into the community. They also installed thousands of sandbags, K-rails and compost filter stockings (a type of wall guard) to prevent dangerous debris from flowing into the storm drains and into the ocean.

In some areas, officials plan to use roads to capture sediment because there are still rubble and ash in the Vaber scars, said Mark Pestreella, director of public works at Los Angeles County.

Los Angeles County officials said they expected the debris flow to hit some homes in the storm. Officials said they had contacted residents, next to their homes was burnt down hillside to alert them of risks. Officials say evacuation orders from certain communities, including Altadna and Malibu, may arise.

“In this event, we do have fragile structures,” Pestrera said. “If our predictions are fruitful… there are some specific fragile structures that are at high security risks, which means they can see brokenness.” Chips are trapped in the back of the house.”

County officials said the area's debris basins have enough capacity to handle dirt, vegetation and other things that may flow along the hills during the storm. According to state reports, while the debris basin helps mitigate the flow hazards of debris, the structure of the San Gabriel Mountains is overwhelmed by the state.

In a storm in 1980, after the Pinecrest fire, the houses were submerged in Altadena when 11 inches of rain fell within 24 hours, which overwhelmed the flood basin of the Rubio Canyon. Since then, the basin’s capacity has increased.

In 2010, during the storm after the station fire, the presumably Canyon Debris Basin went bankrupt, causing damage to 40 homes.

Although last week's series of storms brought only mild rain to the area, officials said the basin of Eaton's handwashing dam was full of debris. After that, the crew cleared 150,000 cubic yards of soil, vegetation and rock from the basin to give the storm extra capacity, Pestra said.

One of the worst debris flows in modern California history occurred when a dirt and rock river passed through the Montecito River in January 2018, killing 23 people and destroying at least 130 homes. The area was burned down less than a month in the Thomas fire. The fire is one of California's most destructive records, burning 282,000 acres and destroying more than 1,000 buildings in Ventura and Santa Barbara counties.

The Times investigation found that government officials were unable to build larger basins, which could make the mudslide less catastrophic, which is why government officials failed to build larger basins. The report also found that Santa Barbara County failed to completely clear existing basins before the disaster, greatly reducing its ability to capture debris.

"We have the capacity to expect the storm scale," Pestreella said Wednesday, adding that staff have been working 24/7 in the last few weeks in transport debris in these areas. ”

Grace Toohey, an era worker, contributed to the report.