It may not seen like it, given the sunny, breezy and cold days the San Fernando Valley has seen in the past month, but rain is coming….in droves.
That’s the forecast of the National Oceanic and Atmospheric Administration (NOAA) for the coming winter season, when they predict higher than normal rainfall thanks to the much anticipated El Niño weather pattern.
“We have been in El Niño since last March and it continues to strengthen,” said Eric Boldt, a meteorologist with the NOAA office in Oxnard.
“El Niño has been in the strong category since Oct. 1, and this could rank it in the top three strongest events since 1950,” he added, before noting that “El Niños usually peak in strength during the winter months.”
According to Bolt, all past strong El Niños have brought above normal rainfall in Los Angeles, which sees an average of just over 15 inches per year. However, when El Niño shows up, we’ve seen between 20 and 30 inches of rain.
What Is El Niño?
It’s a weather phenomenon in which ocean temperatures in eastern tropical Pacific Ocean rise, which leads to the development of a strong jet stream (commonly known as “storm track”) over central and Southern California.
Given the current elevated temperatures measured in the Pacific Ocean, the prediction is that this storm track will become fixed and the region will get repetitive strong winter storms.
During the last El Niño, in the 1997-98 winter season, the strongest on record, there was an endless series of storms from January through March.
With the current ocean temperature pattern, “There is a greater than 60 percent chance of being ‘wetter than normal’ across southwest Southern California from January through march,” Bold said.
The Los Angeles City and County is preparing for this.“Our 14 major dams, 500 miles of open channels, 172 debris basin throughout the county, they’re all prepared for this weather season,” noted Kerjon Lee, spokesperson for the Los Angeles County Department of Public Works.
Lee said that given the predictions for the coming El Niño, “we’ve been doing more maintenance than usual.”
That includes removing accumulated sediment and overgrown vegetation in critical areas that could lead to flooding and landslides.
“We’ve gone through and prepared the best way that we can. We’re hopeful that El Niño brings us rainfall that will make a dent in this year’s drought,” Lee said.
Part of the preparation has also involved building temporary debris structures to help provide additional protection in foothills and canyon neighborhoods.
In some areas they’ve even gone door to door reviewing the conditions in people’s homes and letting homeowners know what they can anticipate, their risk factors and recommendations. This is a free service and anyone can request it.
Because, Lee explains that “our washes and flood control facilities can handle a certain amount of rain water during the winter season, but no facility is designed to handle all the scenarios that may come with El Niño.”
Los Angeles Mayor Eric Garcetti issued a similar warning recently while urging residents to prepare for a particularly wet and damaging winter.
“The rain that we expect can lead to flooding, mudslides, coastal erosion,” Garcetti said at the city’s Emergency Operations Center. “We can see streets lost. We can see homes gone, bridges collapse, large waves, debris flows. And while we can never completely accurately predict the weather, it’s about a 95 percent certainty that we will see a huge impact from El Niño this season.”
Garcetti said that the city reached a deal with four major cell phone service providers to ensure voice and data service will be available on any network if an emergency occurs. He also asked residents to register at www.notifyLA.org so they can receive alerts via phone calls, emails or text messages when emergencies occur.
The Los Angeles Sanitation Bureau is also considering the possibility of stopping trash pick-ups in certain areas during heavy or sudden El Niño storms to help keep catch basins clear of debris and other objects that could block rain from flowing into storm drains and cause flooding.
The Bureau has also cleaned all of the city’s catch basins in preparation for the storms.
A heavy downpour in September flooded a street in Boyle Heights, leaving drivers stranded and clogging the area.
El Niño And The Drought
“One El Niño winter will not end the drought,” Boldt said emphatically.
Part of the problem is that El Niños tend to bring heavier than normal rain in Southern California, but not necessarily in the Central and Northern part of the state. And most of the large reservoirs in the state, mainly Folsom, Oroville and Shasta lakes are in the central and northern region.
“Less precipitation in this region is a concern for drought relief and water supply for much of California,” Boldt said.
Then there’s the issue of collecting the rainfall that we do get in this part of the state.
Lee, of the County’s Department of Public Works, said the existing flood control district is 100 years old this year and throughout that time has been capturing storm water to recharge the ground water basin.
“In an average year we capture 200,000 acre-feet of water,” Lee said.
That’s enough to supply water to two million people a year.
Most of the county’s large water basins are in the San Gabriel Mountains and the upper, Northeast San Fernando Valley, which replenish ground water sources used by a number of water agencies, including the Los Angeles Department of Water and Power (LADWP).
“We see El Niño as a great opportunity to recharge those aquifers that have been unable to recharge due to the drought and the best of our abilities,” he said.
Still, “over the past 10 years we’ve increased our storm water capture capacity by 6.5 billion gallons.”
“Every year, right before storm season we try to have our reservoirs as empty as possible, with the lowest amount of water in order to function, but we haven’t had to do that in recent years,” he said.
However, if there is a heavier than normal rainfall with El Niño, “we release water to our spreading grounds.” In other words, nothing gets lost.
Los Angeles County has 27 spreading grounds. The one in Pacoima, for example, has 12 catch basins and can handle about 7,000 football fields worth of water in any given year. That’s 2.2 billion gallons of water flooding into the grassy fields of the Pacoima spreading grounds annually. As the water falls, it percolates underground recharging the aquifers.
And even you can do your part by collecting water in a rain barrel.
“We anticipate wetter wet years with heavier or more storms in a storm season and drier, dry years. That means, when the rain comes, we need to capture it in one big gulp,” Lee explained.
Everyone is crossing their fingers for that big gulp.
For information and preparation for the coming El Nino, visit www.lacounty.gov/ElNino. You can also access the City of Los Angeles El Niño information page at www.elninoLA.com.