Even in the midst of a strong El Niño, California’s sunny weather this February is not surprising, experts say: The longest dry spell this month — 14 days — is actually less than the average for a strong El Niño winter.
But state water officials said Monday that unless the rainy weather returns with a vengeance, some drought restrictions are likely to continue this summer.
“It’s already a less dire situation, given the precipitation we have received so far this winter,” said Max Gomberg, climate and conservation manager for the State Water Resources Control Board.
“But it would have to rain almost every day — storm after storm after storm — in March for there to be no drought rules this summer.”
Gomberg, whose agency last year imposed mandatory water conservation targets on hundreds of cities across California, with fines for violators, under orders from Gov. Jerry Brown, said state water board officials plan to decide in mid-April whether the rules should continue for another year.
“We’re watching the weather reports like everyone else,” he said. “There’s no way to say definitively yet. If we didn’t get any other storms this winter, we’d still be in a world of hurt. If we have a very wet March, then everyone can rejoice. But the winter’s not over yet.”
This winter already is the best in five years, since 2010-11, for rain and snowfall in California.
The Sierra snowpack Monday was 94 percent of normal. Reservoirs continued to slowly fill. And rainfall totals in many Northern California cities were close to the historic average for this date — 89 percent in San Jose, 87 percent in San Francisco, 132 percent in Eureka, 76 percent in Oakland and 102 percent in Redding — even after a dry February.
A new series of storms is forecast to hit California beginning next week, on March 2.
“There was a lot of hopeful anticipation that we were going to end the drought this winter, and that we’ll be able to wash our cars and water our lawns,” said Bob Benjamin, a forecaster with the National Weather Service in Monterey.
“People are saying what happened to the floods? I bought all these sandbags. But remember: the winter is not over. There is still a good potential for us to reach or exceed our normal rainfall this year.”
If the state ends the winter rain season in April with about an average year’s worth of rainfall, it’s likely that the drought rules will continue in some form this summer, but the mandatory water conservation targets could be eased, Gomberg said. And some areas that have received less rain, like Southern California, might have different targets than places that have received more.
The strongest El Niño conditions ever recorded — measured by the water temperature off Peru near the equator — continue to be in place in the Pacific Ocean, although they peaked around New Year’s Day and are slowly waning. But so far, although January was much wetter than normal in most parts of the state, regular deluges have not occurred. Instead, two odd things have happened, experts say.
In most past strong El Niños, Southern California has received lots of rain, and Washington and Oregon have been dry. This winter, for reasons meteorologists are not certain of, Southern California has been dry, and the Pacific Northwest has received record rainfall.
“All El Niños are different. There is a lot of variability,” said Jan Null, a meteorologist with Golden Gate Weather Services in Saratoga. “This is going to end up being one of the outliers.”
What is not unusual is that every winter in Northern California has long dry spells, he said. Just as it doesn’t snow every day on the East Coast in winter, it doesn’t rain every day in California during winter, even during strong El Niño winters, experts said Monday.
An analysis by Null found that during the five strongest El Niños back to 1950, the longest winter dry spell in San Francisco averaged 17 days in a row. So far this winter, the longest stretched 14 days, between Feb. 2 and Feb. 17.
The longest consecutive dry spell in San Francisco during the strong El Niño winter of 1982-83 was 22 days. In the strong El Niño winter of 1997-98, there was a 17-day stretch without rain. Both those winters delivered nearly double the annual average rainfall.
“People are saying wow, it seems unusual,” said meteorologist Craig Shoemaker, with the Sacramento office of the National Weather Service. “But it is just typical of every winter we get. In El Niño winters, we don’t get more storms necessarily, but the storms have more moisture.”
Shoemaker noted that up to half of California’s entire annual rainfall can come in a few very powerful “atmospheric river” or “Pineapple Express” storms each year.
“There is still time to get some heavy storm systems,” he said. “All it takes is a few to get the rainfall totals really up. We can get 5 to 10 inches of rain in a few days over the mountains.”
Shoemaker noted that despite the warm, sunny weather in February, which was brought on by the temporary return of a high-pressure ridge off the coast, much of the rain so far has been concentrated in Northern California, which is helping replenish large reservoirs such as Shasta, Folsom and Oroville.
The eight-station Sierra Nevada index, a mix of rain gauges near major Northern California reservoirs, was at 108 percent Monday. Officials at the state Department of Water Resources have said that by April, it needs to be between 130 and 150 percent for the drought to end, along with the Sierra Nevada snowpack at 150 percent of the historic average.
Some Bay Area residents are fretting about the dry February. Others are celebrating.
“We’re selling a lot of flowers and grass seed,” said Andrew Broderson, manager at Wegman’s Nursery in Redwood City. “It’s hard to complain when it is 73 degrees out, but we have people saying ‘I know I shouldn’t be enjoying this weather, but I am.'”
Paul Rogers covers resources and environmental issues. Contact him at 408-920-5045. Follow him at Twitter.com/PaulRogersSJMN.