With El Nino on the way, Marin, Sonoma counties get new weather radar to better predict flood-causing storms
With a new El Niño watch announced Thursday by the National Oceanic and Atmospheric Administration, Bay Area weather surveyors are calling all hands on deck in case next winter mimics the winter we just went through here in the North Bay.
County public works agencies are installing a new radar system with a technology the U.S. Navy has long coveted to help predict potential flooding when atmospheric rivers slam the Pacific Coast.
As part of the $30 million project funded by the Federal Emergency Management Agency, California’s Office of Emergency Services and state Department of Water Resources, one radar device was placed off Airport Boulevard near the Sonoma County wastewater treatment plant. Another is going in on Pine Flat Road near The Geysers by early 2024. The cost for the Sonoma County units is $700,000 each.
Marin County’s radar station is due to go in by the end of this year at Mount Barnabe south of Nicasio, at a cost of $2 million. The other locations are identified in Contra Costa, Santa Cruz and San Mateo counties.
“We’re excited to get a few hours of advance notice to get out resources like sandbags,” said Dale Roberts, a project manager and Sonoma Water engineer.
His counterpart in Marin County, Roger Leventhal, an engineer who manages flood control, agreed.
“This system will know where the heavier rainfall will come in,” he said.
The X- and C-band weather radar stations detect out to 50 and 62 miles, respectively. They measure about 10 feet wide by 20 feet high and are mounted on a cargo container. They work by sending out radio waves. What bounces back from the clouds is interpreted to show the location and size of the storm and accompanying precipitation.
They’ll be used to supplement the National Weather Service’s current stations that aim higher in the atmosphere. These radar devices track the 10,000- to 15,000-foot elevation range where atmospheric rivers tend to travel as they approach the coastline, causing a state average of more than $1 billion in flood damage.
The 2022–2023 winter season, which started out as a La Niña year in the early months, resulted in a season for the ages nearly topping the El Niño-fueled winter four decades ago. Those are tropical weather phenomena defined by cold and warm water masses, respectively, off the shores of South America.
The winter of 1982–83 packed a punch with 50.6 inches of rain.
By comparison, Santa Rosa received 43.1 inches, with normal being 28.8 inches, according to the National Weather Service. Napa got 31.3 inches of rain in this water year, 13 inches short of the record. Normal is 24.4 inches.
Marin County endured 39 inches of rainfall, about 7 inches more than the normal amount of precipitation. The record is 61.9 inches.
So far this year, California has seen 31 atmospheric rivers. In most circumstances, atmospheric rivers account for the majority of the damage, leading to 6,650 insurance claims in Sonoma County and 3,152 in Marin, according to the project engineers.
Batten down the hatches
NOAA is gearing up for a 2023–2024 winter with El Niño. Although the Bay Area falls on the cusp of equal chances of experiencing dry or wet conditions, more often than not, it delivers more precipitation to our region.
“Historically, in looking at 20 cases, they tend to favor wetter conditions for Northern California, particularly later in winter,” NOAA climate scientist and El Niño specialist Michelle L’Heureux told the Business Journal. “The odds are in its favor.”
Currently, the El Niño is building, with a 62% chance the weather phenomenon will develop between May and July. This comes after a few years of La Niña. Both are often characterized as bringing opposite results from one end of the Pacific Coast to the other.
In El Niño years, chances are greater of a more active pattern of heavier precipitation from the Bay Area down to Southern California, leaving the Pacific Northwest drier.
But climate has proven not to be a perfect science. For example, this year’s La Nina fizzled out long before the majority of atmospheric rivers dominated the landscape.
“It was the third La Niña. That’s why it got a lot of attention,” L’Heureux said.
NOAA scientists will continue to monitor the potential development of this year’s El Niño. They plan to issue a monthly update on May 11.
Susan Wood covers law, cannabis, production, tech, energy, transportation, agriculture as well as banking and finance. For 27 years, Susan has worked for a variety of publications including the North County Times, Tahoe Daily Tribune and Lake Tahoe News. Reach Wood at 530-545-8662 or susan.wood@busjrnl.com
