SACRAMENTO — Forecasters still expect historically strong El Nino conditions to usher in a parade of storm clouds this winter, but the phenomenon may fizzle by springtime.
The federal Climate Prediction Center still expects that this winter’s El Nino could rank among the three strongest since 1950 and that the typical pattern of southern storms will materialize, officials said on Nov. 12.
Warming sea-surface temperatures in the equatorial Pacific Ocean nearly match those in the fall of 1997 and exceed those in 1972 and 1982, all big rainfall years, the center notes.
But after peaking this winter, the El Nino pattern may recede quickly, returning to the neutral sea-surface and atmospheric conditions that have prevailed through much of California’s four-year drought.
“There is an approximately 95 percent chance that El Nino will continue through Northern Hemisphere 2015-16, gradually weakening through spring 2016,” the CPC concluded in a written update.
Water experts have said California would need more than one wet and snowy winter to emerge from its historic drought.
The last El Nino in California in the winter of 2009-2010 interrupted a three-year drought. But before this year’s recurrence, sea surface temperatures across the equatorial Pacific have mostly been near average since spring of 2012, meaning neither El Nino or La Nina influenced weather patterns. During much of that time, a strong ridge of high pressure off California’s coast blocked storms from entering, causing the current drought.
The latest outlook comes as rain- and snow-producing systems have been passing through California every few days, and that pattern is expected to continue through November. However, the storms have so far been brought by a polar jet stream pushing cold systems down from the north, said Michelle Mead, a National Weather Service warning coordinator in Sacramento.
“Therefore, the recent storms are not associated with El Nino,” Mead said in an email. “Rather, this is a more ‘typical’ Northern California weather pattern for this time of year. It’s just that we haven’t seen a typical fall/winter season over the past four years, so these systems seem more unusual to folks.”
El Nino storms tend to be warmer with higher snow levels, so when the sub-tropical jet stream storm track kicks in, the potential for warmer storms will increase, she said.
Even so, many areas in Central California are off to a fast start in terms of rainfall, exceeding their normal seasonal totals, while many northern areas are still lagging behind their normal precipitation levels for this time of year, according to the National Weather Service.
For instance, Salinas had recorded 2.21 inches of rainfall for the water year as of Nov. 12, well above its average of 1.03 inches, while the 2.35 inches that had fallen on Eureka as of Nov. 12 was well below its seasonal average of 4.11 inches, according to the weather service. The water year begins Oct. 1.
El Nino’s storm track may take hold by the first week of December, when California’s Central Valley could see thunderstorms with afternoon temperatures in the mid-60s, according to AccuWeather’s long-range forecast.