Three atmospheric river storms are headed for California. Will one be enough to end SoCal’s devastating fire season?

After an extraordinarily dry start to the year, three atmospheric river storms are expected to hit California over the next week — with one of them potentially bringing much-needed moisture to the still-withered Southland while packing a more powerful and prolonged punch up north.

The latest forecasting models are predicting rain totals will generally not exceed 1½ inches for much of Los Angeles County, though some areas could see considerably less. Such a soaking would benefit vegetation parched by a historically dry start to the water year and has the potential to finally end one of Southern California’s most destructive wildfire seasons.

This storm coupled with the last — which dropped a half an inch to 1½ inches across the L.A. Basin last weekend — could near a total above 2 inches of rain for the season. Experts say it will take 2 to 4 inches over the region to comfortably consider the wildfire season over.

“It could get us close to that,” said Bryan Lewis, a meteorologist with the National Weather Service office in Oxnard. “There’s still somewhat of a range of outcomes [for rain totals]. ... It might not be widespread enough.”

Though that last storm, L.A.’s first major rainfall of the season, did ease some immediate fire threats, it didn’t quite pack the punch to finally mitigate lingering wildfire concerns. Downtown Los Angeles received a total of 0.54 of an inch of rain during that storm.

That rainfall also didn’t make a dent in worsening drought conditions across Southern California, which have only intensified over the last few weeks, according to the latest report from the U.S. Drought Monitor.

At the end of December, much of Southern California had swung toward drought conditions for the first time in years, but the last few weeks have elevated those concerns, with much of L.A. County now considered in “severe” or “extreme” drought conditions. The only category worse is “exceptional” drought.

The state’s latest snow survey on Friday also found that the state’s snowpack has fallen well below average for this time of year, after a relatively dry January statewide.

Though the conditions may be concerning — drought monitor officials note that the area is seeing “significant short-term drought” that has intensified without considerable rainfall — the previous two wet years mean that the region’s water systems are not yet strained.

And these latest measurements are also nowhere near as dire as they were during the years-long drought that stretched through much of the early 2010s. In January 2015, almost the entire state was considered in extreme or exceptional drought; currently, just 11% of California has reached those levels.

However, the U.S. Drought Monitor report released Thursday did show drought conditions have extended into much of Central California and across the state’s major agricultural valleys, where “the water year has continued to be drier than normal,” the latest analysis said.

There’s a chance next week’s storms could help.

Moderate to heavy rainfall is forecast in Los Angeles and Ventura counties from Tuesday through Thursday, according to the weather service office. It could rain for many hours each day, with the highest chance of precipitation between Tuesday afternoon and Wednesday afternoon.

Lewis said rainfall will stem from one of the atmospheric river storms that will more directly, with more intensity and moisture, hit the northern half of the state. The Southland will get only the remnants of that system as it lingers south.

“We’re on the edge of it,” he said.

However, forecasters warned that these rains could bring a minor-to-moderate risk for debris flows and mudslides in some of the recent burned areas, such as around the Palisades and Eaton fires in Los Angeles County — a concern that was mostly alleviated during last weekend’s winter storm.

The wildfires have made soils repellent to water, and during heavy rains, water can easily flow across burn scars and pick up rocks, branches and sometimes massive boulders, sending debris flowing downhill quickly — with destructive and deadly consequences.

“There is some risk … there is likely to be a good amount of areas that will see periods of [rain falling at a rate of] a half inch an hour, and that is the threshold for debris flows,” said Rose Schoenfeld, a meteorologist with the National Weather Service office in Oxnard. “So we may see some impacts with this storm.”

(National Weather Service)

Under the most likely scenario, L.A. and Ventura counties could see half an inch to 1.5 inches of rain from Tuesday to Thursday.

But there’s also a worst-case scenario, where downtown L.A., Long Beach and Redondo Beach could get more than 1.6 inches of rain, and Santa Clarita more than 1.8 inches, Santa Barbara more than 3 inches and Cambria nearly 4 inches.

But with the storm still far enough out, there’s also an underperforming scenario, where downtown L.A. could get one-third of an inch of rain. Both the worst-case and “low amount” scenarios have a 10% to 20% chance of occurring, forecasters said Friday.

(National Weather Service)

The chance of rain is lower in the Inland Empire and San Diego and Orange counties. The National Weather Service said there was a slight chance of rain in that region on Tuesday and also on Wednesday.

There are chances of light rain in Santa Barbara and San Luis Obispo counties from Friday night through Monday. From Tuesday through Thursday, those counties have a 30% chance of high amounts of rain, and a 50% chance of moderate rainfall.

Wide swaths of Southern California have seen only one significant rainstorm in more than eight months — producing for many areas a record dry start to the water year, which began Oct. 1. In the lead-up to the Palisades and Eaton fires this month, the intense dryness kept vegetation tinder dry — a recipe for disaster when combined with strong Santa Ana winds and an ignition source.

Northern California did have a wet start to the rainy season but also experienced a dry January. After the area enjoyed robust rain in November and December, when precipitation in the Sierra Nevada was above average, precipitation there is now merely average.

The northern Sierra, for instance, has had 26.5 inches of cumulative precipitation. That’s 98% of the average for this date, but it’s the first time in months the region has dipped below 100%. The northern Sierra is a key piece of the state’s water supply, which relies on a natural reservoir of snow and ice in the mountains that slowly melts to refill reservoirs in the spring, summer and fall.

January is not quite over yet, but so far, downtown San Francisco has endured its third-driest January on record, with just 0.19 of an inch of rain so far this month, according to Nicole Sarment, a meteorologist with the weather service’s office in Monterey. That’s just 4% of the city’s average January rainfall of 4.4 inches.

Two big plumes of moisture are headed toward California with precipitation expected in much of the state.

(National Weather Service)

But that dry spell looks set to end — and not with a whimper.

Northern California is primed to get three atmospheric river storms, according to Courtney Carpenter, a meteorologist with the weather service’s Sacramento office. Atmospheric river storms are long plumes of water vapor that can pour over from the Pacific Ocean into California. They carry so much water that they’re said to be like a river in the sky. Just a few atmospheric river events can bring California from one-third to one-half of its annual precipitation.

The first storm for Northern California started arriving Friday and could last through Sunday, with a second arriving Monday and a third not far behind on Wednesday, Carpenter said.

The first storm will probably bring accumulating snowfall to just the higher Sierra peaks, according to the weather service office in Reno. The second is expected to be colder, potentially bringing heavier mountain snow and more widely affecting travel, Carpenter said.

In the Sacramento Valley, given the dry weather, “we’re not expecting widespread major flooding impacts across our area, but do look for extended periods of moderate, heavy rain, significant rises on area waterways ... localized flooding in our usual trouble spots, and the potential for mud and rockslides in the mountains and foothills below the snow line,” Carpenter said.

Sacramento could get 2 to 3 inches of rain during this weekend’s storm, and Donner Peak could see 6 to 8 inches of snow. Sacramento could see another 2 to 3 inches of rain during next week’s storm, with potentially another 30 to 36 inches of snow falling at Donner Peak.

The area of the 429,603-acre Park fire, which burned through Butte and Tehama counties north of Chico, is not expected to see intense enough rainfall to trigger debris flows, Carpenter said, but “you can expect increased muddy and woody runoff,” which occurred in northern Chico neighborhoods in November.

At least six days of rain are expected for the San Francisco Bay Area and surrounding areas, and there could be moderate effects in San Francisco, the North Bay and San Mateo County, as well as in Santa Cruz and San Benito counties.

The Bay Area has a better-than-even chance of 1 inch of rain for the first atmospheric river storm, hitting Friday through Sunday. More significant rainfall is expected next week.

The “main question is timing and extent of moderate-to-heavy rainfall,” the weather service office in Monterey said, which could cause elevated levels of water in creeks and streams and minor street flooding.