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Washington snowpack reaching normal levels

Matthew Weaver

Capital Press

Washington snowpack levels returned to normal as a result of February storms, which is easing water managers' concerns. But soil moisture is still lacking following a dry fall, says Scott Pattee, water supply specialist for USDA Natural Resources Conservation Service.

Recent storms have Washington state’s snowpack approaching normal levels, relieving a fear that farmers across the state might face a shortage of irrigation water this summer.

The snowpack recently reached 92 percent of normal statewide, said Scott Pattee, water supply specialist for USDA Natural Resources Conservation Service in Mount Vernon, Wash. At the beginning of February, snowpack was 55 percent of normal.

Snowstorms last weekend didn’t have much impact, Pattee said. Some NRCS snow survey sites reported 10-15 inches of added depth, which is seasonally normal for the time of year, he said.

Several sites in the Cascade Mountains are reporting the snowiest February on record, said Jeremy Wolf, meteorologist for the National Weather Service office in Spokane. A location near the upper end of Lake Chelan typically averages 42 inches of snow for the month. It received 142 inches this month, he said. The previous record was 117 inches.

Winthrop, Wash., and the Methow Valley typically receive 8 inches during February, and this year received 42 inches, he added.

A state water availability group — made up of water managers, meteorologists and state resource agencies — convened in early February to consider drought declaration recommendations. The group decided to defer until March because similar recoveries have occurred in the past, Pattee said.

The snowpack serves as the water bank for summer stream flow, Katherine Rowden, hydrologist for the National Weather Service office in Spokane, said.

A low snowpack year would mean low stream flows, which can impact farmers drawing water for irrigation. Under minimum stream flow requirements, the state Department of Ecology can cut off junior water right users, she said.

The Northwest snowpack can receive a week or two of strong storms and make up a deficit quickly, said Nic Loyd, agriculture meteorologist for Washington State University’s AgWeatherNet in Prosser.

For much of the winter, a ridge of high-pressure, warm air blocked most storms from forming and moving into the Northwest. In February, a trough of cold air off the coast allowed low-pressure systems to track into the state with heavy precipitation.

“I’m pleasantly surprised — even three weeks ago I wouldn’t have thought there would be this amount of an improvement,” Loyd said.

Though the mountain snowpacks have caught up, precipitation in valleys and central basins is still below normal, which could impact dryland farmers, Rowden said.

Soil moisture deep in the ground is depleted every fall and needs to be recharged for the growing season, Pattee said.

“I highly doubt there’s going to be much concern now, but we will to continue to watch things,” Pattee said. “These long-range weather forecasts are so unstable, we just don’t know what’s going to happen.”

Pattee doesn’t expect snowpacks to hit 100 percent of normal.

“It’s kind of like squeezing that last little bit of lemon juice out of the lemon,” he said. “You’re going to have to squeeze pretty darn hard to bring us up to normal.”

The snowpack has at least another month to go before peaking, Loyd said, which means at least an average snowfall is needed into the spring.

“It’s a little early to say for sure that we’re going to be OK for the entire summer,” he said.


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