Oregon snowpack sees strong start to season
Dec 20, 2016
Monitors remain ‘cautiously optimistic’ for water implicationsBy Hilary Corrigan
Oregon’s snowpack so far this season has those who monitor it hopeful about water levels for next year.
“We’re cautiously optimistic with a start like this,” said Scott Oviatt, snow survey supervisor at the Natural Resources Conservation Service in Oregon, part of the U.S. Department of Agriculture.
On Friday, Oregon was at 139 percent of the statewide average snow water equivalent — the amount of water in snow — compared to 131 percent in 2010 and 217 percent in 2001, based on data from the past 30 years. The Upper Deschutes Basin had a 143 percent-of-normal reading and Ochoco Meadows was at 148 percent. The percent of normal refers to the current snow water equivalent at sites in a basin compared to the average value for those sites on that day. On Monday, the Upper Deschutes Basin had a 133 percent reading and Ochoco Meadows 135 percent.
“We’re doing the best start to the season since 2001,” Oviatt said.
Snowpack refers to the mass of snow on the ground that will fill waterways as it melts. Snowpack is critical to waterways, including stream flows and water temperature through the summer. That water is used for various purposes, such as irrigation, fisheries and drinking. Snowmelt from the mountains provides about 70 percent of the water supply in much of the Western U.S., according to the Natural Resources Conservation Service. The service uses the measurement of snow water equivalent to determine available water in snowpack — the depth of water that would result from melting it.
The service measures snowpack, precipitation, temperature, wind, soil moisture and other factors at various sites throughout the state using both automated data collection and manual surveys. The automated systems can also measure the weight of snow at a site and calculate the snow water equivalent — the amount of water in that snowpack.
How long snow sticks around is a critical component.
In mid-April 2016, for instance, record temperatures melted off a solid snowpack fairly quickly. The early melting meant earlier peaks in river flows that usually occur later in summer. For the Upper Deschutes and Crooked River basins, the snowpack at some sites melted off up to three weeks earlier than normal.
An early-December start and an early buildup of snow can be a potential indicator of cool, wet weather through winter and of a good amount of water available in the spring, Oviatt said. But if warm temperatures hit high elevations now, rain can result on top of existing snow, leading to possible flooding.
“There is a downside,” Oviatt said. “But hopefully we’ll stay cool.”
The conservation service monitors the data every day of the year and publishes monthly water supply outlook reports from January through June. For more information on Oregon’s measurements, visit www.or.nrcs.usda.gov/snow.
— Reporter: 541-617-7812,
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