Weather

Warm weather complicates El Niño, drought outlook

Video: NOAA assesses El Nino's potential for 2015-16 winter

Forecasters at the National Oceanic and Atmospheric Administration provide possibilities and probabilities associated with the potential impact of the weather phenomenon known as El Nino on California, the western U.S. and the country in general d
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Forecasters at the National Oceanic and Atmospheric Administration provide possibilities and probabilities associated with the potential impact of the weather phenomenon known as El Nino on California, the western U.S. and the country in general d

Like a lot of Californians, Sue and Steve Duroncelet are getting whipsawed by conflicting weather. After dutifully letting their Land Park lawn go brown, the couple now are having to trim their trees to prepare for El Niño storms while they sweat out an early-fall heat wave.

“We’re ready for cold air,” Sue Duroncelet said Thursday as she and her husband walked through midtown Sacramento.

It’s been warm in Sacramento, way too warm for mid-October, the latest twist in a year of often maddening weather patterns. While a cooling trend may give some immediate relief, the National Oceanic and Atmospheric Administration says higher-than-normal temperatures likely will be the rule and not the exception this fall and winter. That could be a problem: Warm weather could hinder how much drought relief California will get when the much-anticipated El Niño arrives and the precipitation starts to fall.

The oceanic agency delivered its latest winter forecast Thursday, and it was something of a mixed bag. It reiterated earlier predictions that California can expect one of the strongest El Niño winters ever, with above-average rains increasingly likely for the central and southern parts of the state.

Northern California, home to most of the state’s major reservoirs, remains tougher to forecast. The agency said the Sacramento Valley has an 80 percent chance of getting normal precipitation this winter, and a 34 percent to 40 percent chance of above-average precipitation.

However, the agency said exceedingly warm temperatures will mean much of that precipitation is likely to fall as rain instead of snow, undermining El Niño’s ability to ease the drought substantially. What California needs most is a generous snowpack in the northern Sierra Nevada, capable of keeping reservoirs, rivers and canals filled with runoff well into next spring and summer.

Overall, “the winter outlook is good news for California,” said Mike Halpert, deputy director at the federal agency’s Climate Prediction Center in College Park, Md. But he said El Niño likely will translate into “drought improvement,” not “drought removal.” The heaviest precipitation should begin in January.

Speaking on a conference call with reporters, Halpert said California’s accumulated water “deficit” is almost certainly too steep to remedy in one winter. California needs about three times the normal precipitation to bring the state back into balance; the wettest winter in modern history, in 1983, brought twice as much precipitation as normal.

“One season of above-average rain and snow is unlikely to erase four years of drought,” Halpert said.

Meanwhile, the unusual fall heat is making it harder for some area water district managers to reach their mandated conservation goals. The Fair Oaks Water District had cut water use by 39 percent since June, when statewide mandates went into effect. In September, the savings trailed off to 25 percent, said general manager Tom Gray. He said the challenge is that while most homeowners have contentiously let their lawns die, they’re still watering the trees and shrubs that otherwise would wither in the heat.

“Even those same water-responsible people are still using outdoor irrigation,” Gray said. “At this time of year, (normally) they’d be trending back. They’re not.”

The unseasonable weather also has kept state fire crews on full alert. They responded to 125 new fires last week. A 600-acre fire near Hollister is still burning, said Daniel Berlant, a spokesman for the California Department of Forestry and Fire Protection.

“We’ve not changed or talked about the reduction of staffing that we’d normally be doing this time of year,” Berlant said.

The unseasonal heat is enough to frustrate even meteorologists who study weather patterns for a living.

“Fall’s a nice time of year. You cool off. You shouldn’t be in mid-October and it’s 95 degrees outside,” said Jason Clapp of the National Weather Service in Sacramento, ending the last sentence with a disgusted “ugh.”

Temperatures hit a high of 96 on Tuesday in Sacramento, a record for Oct 13. Although temperatures have cooled somewhat, Thursday’s high downtown of 90 was still several degrees above normal. Earlier predictions of a wet weekend have given way to a mere 20 percent chance of sprinkles late Saturday.

Mike Anderson, the state climatologist, said the warm spell “has a lot to do with some lingering summer patterns. We have a lot of warm air. We haven’t quite gotten into our fall pattern.”

Fall’s a nice time of year. You cool off. You shouldn’t be in mid-October and it’s 95 degrees outside.

Jason Clapp, National Weather Service in Sacramento

El Niño is a phenomenon marked by warming sea temperatures in the Pacific during summer and fall. It usually unleashes a torrent of rain in Southern California, but the impact is generally less predictable in Northern California.

Halpert, of the national oceanic agency, said this winter’s El Nino is shaping up as one of the three strongest in the past half-century, and the chance of a wet winter in Northern California is improving. “As we get closer to winter, we’re probably tilting a little more toward a wetter-than-average winter” in Northern California, he said.

Heavy rains would help replenish the region’s underfilled reservoirs, at least in the short term. Folsom Lake fell to its lowest level in 23 years this week, bringing the giant reservoir to just 17 percent of capacity.

In the Sierra, however, snow would be better than rain. That would translate into snowmelt that provides additional water next spring and summer, over and above what can be safely stored in Folsom, Shasta and other reservoirs during the storm season. The difference between a rainy winter and a snowy one can be enormous. The Sacramento region received two-thirds of its normal rainfall last winter, but the Sierra snowpack was just 5 percent of normal, leading to record drought conditions.

Asked about the expected snowpack around Lake Tahoe this winter, Alan Haynes, a hydrologist with the federal agency’s California Nevada River Forecast Center, said “it might be slightly more likely to be wet and slightly more likely to be warmer.”

Tahoe tourism officials will embrace that forecast. After a winter that forced at least seven Tahoe-area ski resorts to shut down prematurely, the possibility of any kind of meaningful precipitation is a reason for hope.

“If you have any kind of moisture, your odds of it being cold enough and white enough go up,” said John Rice, general manager at Sierra-at-Tahoe. The resort closed two weeks ahead of schedule last winter.

Dale Kasler: 916-321-1066, @dakasler

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