By Jason Henry, San Gabriel Valley Tribune and Steve Scauzillo, San Gabriel Valley Tribune
There’s a high probability that Southern California will experience drought-busting rains and local flooding this winter, after meteorologists announced Thursday that the chance of a strong El Niño had reached above 90 percent.
If the forecast holds, weather experts from the National Oceanic and Atmospheric Administration and the National Climate Prediction Center said the El Niño event would be among the strongest on record dating back to 1950.
Unlike last summer when NOAA meteorologists tracked an El Niño in the equatorial Pacific region that petered out, this one continues to gain in strength, said Mike Halpert, deputy director of NOAA’s Climate Prediction Center in College Park, Maryland.
“This is a developing event that isn’t going to go away tomorrow,” Halpert said Thursday during an interview.
A CONSISTENT RISE IN PROBABILITY
When NOAA began tracking El Niño in March, the chance of it sticking around by November-December was 50 percent, he said. That probability grew to 70 percent in April, 80 percent in May and is now above 90 percent for the winter. The chance of it lasting through early spring 2016 is 80 percent.
Last year, Jet Propulsion Laboratory climatologist Bill Patzert tamped down the enthusiasm by saying it would never arrive. This spring, Patzert has been leaning toward saying this could be a “Godzilla El Niño” similar to the one he predicted in 1997-1998, which brought torrential rains and flooding to Southern California.
“It is night and day compared to last year,” Halpert said. “Last year we never made it to advisory status. This year, we’ve seen an atmospheric response, such as subsurface temperatures rising.”
CAN EL NIÑO END THE DROUGHT?
An El Niño is a climate pattern that can indirectly affect weather. Evidence includes warmer tropical waters in the Pacific, which in turn release heat to the atmosphere, causing storms in the central and eastern tropics. Air patterns can shift the jet stream and act like a magnet, attracting storms from the Pacific into the western United States.
The atmospheric changes measured by NOAA scientists include almost a 4 degree Fahrenheit rise in normal sea surface temperatures, NOAA reported Thursday. Scientists also point to weakening near-surface easterly winds that warm up ocean waters.
Still, an El Niño, even a strong event, does not guarantee enough rain will fall to solve California’s four-year drought, Halpert said. It increases the odds to 50 percent to 60 percent of Southern California experiencing above-average rainfall amounts this winter. If true, Southern Californians would see the most rainfall between January and March, he said.
For flood control efforts, the rainfall as both a risk and an opportunity. During the intense El Niño in 1997, flood control projects captured 350,000 acre feet of stormwater. A weaker El Niño in 2004 brought in 600,000 acre feet of storm water.
“They really had the foresight when they designed the system to both control and conserve the floodwaters,” said Keith Lilley, principal engineer with the L.A. County Flood Control District. “Just because it’s El Niño, we shouldn’t panic that this is something beyond what we’re prepared to respond to.”
IS SOUTHERN CALIFORNIA PREPARED FOR EL NIÑO?
To prepare for above-average rainfall, workers have already begun cleaning out debris basins near foothills denuded by recent wildfires. In Glendora, where the 2014 Colby fire scorched nearly 2,000 acres, all five basins above the city were emptied to capture mud and water from the mountainside in the event of a downpour. The burned landscape leaves the hillside unable to absorb water, increasing the likeliness of flooding and mud flow. Rainfall that exceeds a half an inch per hour, or which lasts for days, could put residents at risk.
Since the fire, the city gave out more than 100,000 sandbags and installed 2 miles of barriers. It constantly watches the weather, El Niño or not, said City Manager Chris Jeffers. In the 1960s, mudslides brought on by heavy rain in a burn area destroyed 30 homes. Today, more than 1,000 homes rest below the scars of the Colby fire.
“They could all be touched by the most extreme conditions of mud and debris flow,” Jeffers said.
Similarly, the Calgrove fire near Santa Clarita could result in runoff, according to Lilley. The district is working with the city and residents to prepare for the coming storms.
“Wherever we have the burn areas, those are kind of hotspots that we watch,” he said.
Throughout the county, flood control continues to clean out reservoirs, debris basins and flood channels, Lilley said. To the south, where the land is flatter, the county is checking that its pumping stations are working properly.
“We prepare for the worst, and hope for the best,” he said. “There’s just a chance that we might actually get the big storm that we’ve prepared for.”
Residents can get a copy of the Los Angeles County Emergency Survival guide by calling 211 LA COUNTY at 1-800-339-6993 or visiting www.lacoa.org.
Both the desert regions and homes near burn areas in San Bernardino County could be at risk.
“Historically during an El Niño event, troubles occur in Forest Falls, Mount Baldy, foothill areas at the base of the San Bernardino mountain range and the desert regions,” San Bernardino County fire spokeswoman Tracey Martinez said. “Typically in the desert regions, there are no drainage curbs roadside that control the water flow and runoff, thus causing more roadways to wash away and drainage’s to fill up quicker.”
In 1980, the devastating Panorama fire that burned more than 24,000 acres, destroyed more than 300 homes, damaged 49 homes and caused the deaths of four civilians and 77 injures, was followed by torrential rains bringing much of the mountainside down into the city.
“County agencies have been working nonstop since before the fires were contained to prepare residents for flooding and to lessen the effects of post-fire mud and debris slides,” Martinez added.
A storm in July collapsed part of the 10 Freeway and flooded San Bernardino and Riverside counties.
Daily Breeze staff writer Doug Saunders contributed to this article.