Here’s something you haven’t heard much around California during the past 14 months: Get out your umbrellas.
Forecasters say significant rain is in the future — both this week and possibly next winter, with computer models showing promising signs of an El Niño, the phenomenon when Pacific Ocean waters warm up, often bringing wet winters to California.
It’s a double dose of positive news for the drought-stricken state. While predicting weather too far into future is still unreliable, this week’s storm system charging in from the Pacific Ocean is a safer bet: The storm is expected to hit the Bay Area on Wednesday afternoon, bringing up to four days of steady rain that meteorologists say should provide a desperately needed soaking.
“It’s pretty promising. All the computer models are in agreement, and that’s a really good sign,” said Duane Dykema, a meteorologist with the National Weather Service in Monterey. “It looks like we’ll get a series of storms with widespread rainfall.”
Rainfall should vary from 2 to 5 inches across much of the Bay Area and the rest of the state, he said, with 2 to 3 feet of new snow in the Sierra Nevada.
And unlike the last significant rainfall, on Feb. 7-9, this storm is shaping up to be much more of a classic winter event, with winds up to 50 mph, power outages and some potential flash flooding. Gusty winds will be most severe on Friday.
Radar images and computer models show this storm hitting nearly all of California, unlike the last storm, which was a narrow “Pineapple Express” from Hawaii that drenched Marin, Sonoma and Mendocino counties, but left most Bay Area cities south of San Francisco with barely any reason to flip on the windshield wipers.
The rain is desperately needed. Since July 1, San Francisco has had only 5.85 inches, or 35 percent of normal for this time of year. Similarly, San Jose, with 2.67 inches, is at 26 percent of normal and Oakland, with 4.36 inches, is at 31 percent.
A storm that dumps 2 to 5 inches on the Bay Area could double those totals, but still would leave most cities with half to two-thirds of their normal precipitation.
But scientists see something further into the year that could provide relief: increasing conditions that indicate the arrival of an El Niño.
In November, researchers at NOAA, the National Oceanic and Atmospheric Administration, reported there was a 36 percent chance of El Niño conditions developing by August of this year. Now, in an update earlier this month, they have raised the probability to 49 percent.
“There’s been an uptick recently. More models favor El Niño,” said Jon Gottschalck, acting chief of operational prediction at NOAA’s Climate Prediction Center in College Park, Md. “We certainly don’t want to promise anything, but conditions are looking better.”
The conclusions are based on ocean temperature readings from dozens of buoys, wind measurements, satellite images and more than a dozen computer models from scientific agencies around the world.
Meanwhile, earlier this month, an international team of scientists published a paper claiming there is a 75 percent chance of an El Niño occurring next winter. Their methods sparked a debate among researchers, not all of whom agreed, but the news further ignited hopes that next winter will be wet, perhaps ending the drought.
An El Niño doesn’t guarantee that California will receive drenching winter rains. But the stronger the conditions and the warmer the water, the greater the likelihood.
Since 1951, there have been six winters with strong El Niño conditions. In four of them, rainfall between the Bay Area and Bakersfield was at least 140 percent of normal. Some of California’s wettest winters occurred during those strong El Niño winters, including 1982-83, when mudslides killed 10 people along Santa Cruz County’s Love Creek and San Jose’s Coyote Creek burst its banks, flooding Alviso under 8 feet of water.
In more moderate El Niño years, when ocean waters are warmer than normal, but not extremely warm, rainfall sometimes is above normal, but just as often below.
For example, during a moderate El Niño in 2002, rainfall was 103 percent of normal in Northern California, but in a similarly moderate El Niño in 1986, rainfall was just 60 percent of normal.
“While it increases your odds of a good rainy season come fall and winter, there’s no guarantee,” said Mike Halpert, acting director of NOAA’s Climate Prediction Center. “We’ve seen some El Niños that didn’t pan out. But it is better to have an El Niño than a La Niña.”
Often, La Niña conditions — when Pacific waters near the equator are cooler than normal — are associated with dry weather in California.
Regardless of next winter, Bay Area residents are watching for this week’s coming rain.
“I can hardly wait,” said Ada Parsley, a retired artist who lives in San Jose. “I scattered a lot of flower seeds in the field behind my house. With this rain, I hope we have a lot of flowers back there.”
Seven years ago, Parsley tore out her grass and replaced it with red lava rocks and rock statues. Her water bill dropped significantly.
“Anybody can do it,” she said. “It’s economical. You can put pea gravel down there. You can rake it into patterns and make a Zen garden. Just create something. You don’t have to have grass.”
Paul Rogers covers resources and environmental issues. Contact him at 408-920-5045. Follow him at Twitter.com/PaulRogersSJMN
