precipitation and snowpack lagging to varying degrees in the Columbia Basin,
the first water supply and streamflow forecasts for 2019 are reflecting those
Northwest River Forecast Center in Portland conducted its first briefing of the
year on Jan. 3, re-capping the 2018 water year for the region, outlining
current conditions and the outlook for the water year that is underway.
Kevin Berghoff said that so far, there has been below-normal precipitation
across the Upper Columbia and Snake River basins, resulting in snowpack that is
well below normal. Well below normal snowpack conditions persist in the
Cascades, particularly in Oregon.
on those conditions, the April through September water supply forecast ranges
from 88 to 90 percent of the historic average on the Upper Snake; 79 percent on
the Boise River; 99 percent on the North Fork Clearwater; 90 percent on the
Lower Snake; and 95 percent of normal on the Lower Columbia River at The Dalles
the Cascades, current projections for April through September streamflows range
from a high of 99 percent of normal on the Skagit River near Concrete, Wash.,
to a low of 81 percent of normal on the Willamette River at Salem, Ore.
Columbia Basin’s overall snowpack picture is beginning to resemble
characteristics of last year’s conditions, with the healthiest snowpack in the
Upper Columbia and Snake River Basins and the driest areas being concentrated
in central and southwest Oregon.
you recall last year there was a fairly stark dividing line between basins that
had above-normal snow water equivalent and basins that were deficient,”
some exceptions, snowpack conditions appear to be developing in a similar way,
with recent warm and dry weather impacting seasonal precipitation measured from
last Oct. 1 through Dec. 31. in the
Columbia River basin above Grand Coulee Dam, three-month precipitation is at 88
percent of normal, compared to 102 percent of average for the same period last
in the Snake River Basin is at 85 percent, compared to 98 percent last year;
and precipitation in the Columbia River Basin above The Dalles is at 85 percent
compared to 98 percent last year.
weeks now, NOAA’s Climate Prediction Center has had an active El Nino Watch,
based on above normal sea surface temperatures in eastern Equatorial Pacific
Ocean. Those sea temperatures have yet to “couple” with atmospheric conditions.
late winter and early spring tend to be most favorable months for coupling, so
forecasters still believe weak El Nino conditions will emerge shortly” and
continue into spring, the CPC said in its monthly forecast issued this week.
highlighted historical data showing how weak El Nino systems do not necessarily
translate to warm and dry conditions in the Pacific Northwest. Strong El Nino
systems, however, are more likely to produce those conditions in the Northwest.
could make the case that there’s just about an equal number of El Nino years
with above-average precipitation as below average in weak El Nino years,”