It’s early in the season, but the winter snowpack, which determines irrigation water availability for many Pacific Northwest producers, is off to a good start.
The USDA’s Natural Resources Conservation Service said the snowpack is building, especially in the Northern Cascades and the Central and Northern Rockies. Some of the agency’s automated Snow Telemetry, or SNOTEL, stations in those regions recorded more than 2 feet of snow at the end of October. Much of that came from the cold “atmospheric river” that flowed across the Northwest the weekend of Oct. 21-22, bringing heavy rain and snow before giving way to a stretch run of sunny fall days.
As a result, reservoirs are filling and the precipitation in most river basins is well above normal for this time of year. In Oregon, precipitation was measured at more than 100 percent of average in 11 of 13 basins. The Willamette basin stood at 176 percent of average, and the Hood, Sandy and Lower Deschutes region measured 186 percent of average.
The numbers should be taken with a grain of salt, however, because they measure and compare only from Oct. 1, the start of the water year for statistical purposes. Averages are calculated from measurements taken from 1981 to 2010.
The National Oceanic and Atmospheric Administration predicts a cool and wet winter for northern tier states that include, Oregon, Washington and Idaho east to the Dakotas. The rest of the lower 48 states will have warmer and drier weather this winter, according to NOAA.
Julie Koeberle,hydrologist with the NRCS snow survey office in Portland, said the La Nina pattern forecast for this winter usually correlates with a good snow year in northern tier states.
“Overall it’s good news for most of the state and the Pacific Northwest,” she said. The pattern often doesn’t hold for parts of Southern Oregon, however. The Owyhee and Lake County basins, in Southeast Oregon, are the only ones with less than average precipitation so far this water year, according to NRCS.