Weather

Much of Sierra sees big rainfall, snow totals in May

A snow-covered rock is surrounded by flowing water near the headwaters of the south fork of the American River at Strawberry.
A snow-covered rock is surrounded by flowing water near the headwaters of the south fork of the American River at Strawberry. rpench@sacbee.com

For a lone, lovely month, it hasn’t much felt like a drought in the Sierra Nevada.

Rain and snow have fallen week after week during May in the high country. Temperatures have dropped below normal most days, reducing the amount of water lost to evaporation. Southern California has received an unusual amount of rain, too: San Diego has seen 2.4 inches of precipitation in May; it normally gets 0.21 inches.

Climatologists said the wet weather has not put much of a dent in California’s drought, now in its fourth year. Yet some experts said the recent precipitation could offer a promising, albeit uncertain view, of what’s in store for winter, even raising the prospect of a rain-filled El Niño season.

As of Friday, more than 4 inches of water had fallen in parts of the Sierra Nevada, some of it as rain, some as snow. That’s more than five times the normal amount in some places. It has rained more during May in some parts of the Sierra than it did during the entire winter, federal data show.

“We are kind of floored,” said Arya Degenhardt, spokeswoman for the Mono Lake Committee, an environmental group in Lee Vining. “As of right now, precipitation – it’s at 4 inches (for May). It’s kind of off the charts. The lake has risen over 2 inches. That is huge for us, especially after four years of drought.”

The wet, cold weather extended into Nevada and parts of Southern California. But the Central Valley and North Coast remained mostly dry, leaving many in Sacramento oblivious to the storms happening up the hill.

State officials and climate experts said the rain will help fill depleted mountain reservoirs and hydrate thirsty high country trees and plants. But after such a dour winter, the rain is more a respite than a rescue from the historic drought.

“The net effect in the larger scheme of things is to simply slow down the drought juggernaut,” said Kelly Redmond, deputy director and regional climatologist for the federal government’s Western Regional Climate Center in Reno.

Redmond and other climatologists watched the weather patterns in May with an eye toward what they might portend for next winter.

The rain and cold weather, they said, may have been partially caused by an El Niño weather pattern. The term “El Niño” generally refers to a period in which the surface waters of the Pacific Ocean are warmer than usual near the equator. The temperature shift disrupts normal weather patterns, often bringing heavier-than-usual precipitation to California. The drenching rains in the winters of 1982-83 and 1997-98, accompanied by mudslides and other woes, were attributed to El Niño. The last El Niño, in the winter of 2009-10, brought only slightly above-average precipitation.

Several climatologists expressed hope that an El Niño weather pattern could settle in and bring more rain.

Bill Patzert, climate analyst at NASA’s Jet Propulsion Laboratory in Pasadena, is among those who are optimistic about the coming winter. He said the destructive storms that hit Oklahoma and Texas this week were related to El Niño, and he expects significant precipitation in California this winter.

“It’s pretty big in terms of size and intensity. This thing looks as promising as anything I’ve seen in the last ... 18 years,” he said.

But Patzert and others cautioned that the upcoming El Niño is likely to strike mainly in the southern half of the state, missing the major mountain ranges and reservoirs that act as the primary source of California’s vast freshwater delivery network. That would limit El Niño’s effectiveness as a drought remedy.

“Where we really want the snowpack and the really steady winter rains is Northern California,” Patzert said.

Michelle Mead, a meteorologist with the National Weather Service in Sacramento, agreed that an El Niño is forming, but she said it probably will not pack much of a punch. “It’s going to increase our probabilities (of rain) up to 70 percent, but it’s not guaranteeing it will be enough rain to end the drought,” she said.

Prognostications aside, many in the Sierra Nevada are simply thrilled that so much precipitation fell on their lakes, streams and trees.

“We’ll take all the rain we can get,” said Robert Peek, a ranger at Bodie State Historic Park in Mono County, where total precipitation has been measured at more than 6 inches so far in May.

At Mono Lake, the drought has raised the specter of dust storms and harm to wildlife. The lake's streams typically provide billions of gallons of drinking water each year to Los Angeles. “Between the rain that falls on the lake itself and the actual snow in the snowpack ... it’s really good,” Degenhardt said.

Even so, it will take a lot more rain to bring Mono Lake, a huge, shallow body of water east of Yosemite that provides critical habitat for millions of migratory birds, back to normal levels. The lake has lost more than 5 feet of depth since the drought began, Degenhardt said.

And, as May turns into June, the dry summer will arrive, leaving little chance of precipitation until winter.

“May helps a lot, but in the bigger picture, we also want to keep perspective,” Degenhardt said. “People need to conserve water.”

Despite the rain, nine of the state’s 12 key reservoirs saw water levels drop in May, including Folsom Lake and Lake Shasta, state figures show. The losses were greatest in Northern California reservoirs.

But the rain was enough to stay the hand of the State Water Resources Control Board, which regulates the state’s complex water rights system. In early April, the board warned senior water rights holders – those with the oldest rights and first dibs to water – that they could see those rights curtailed. As of Friday, the board still hadn’t issued curtailments to senior water rights holders.

“We want to make sure we don’t cut it off sooner than we need to,” board chief deputy director Caren Trgovcich said after the first batch of May storms.

Sierra precipitation

Rain and snow in May exceeded normal in much of the Sierra. Total water in inches:

Weather station

May 2015

Normal

Bodie

6.06

0.70

Boca

1.86

0.98

Truckee

1.69

1.30

Lee Vining

4.15

0.62

South Lake Tahoe

2.01

1.07

Grant Grove

2.84

1.60

Yosemite Village

2.17

2.28

Source: National Climatic Data Center

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