GENERAL OUTLOOK
Dry conditions with slightly above average temperatures took a bite out of expected Spring runoff volumes. Dry soils and low reservoir storage will cause further reductions in runoff volumes. Volumes in several areas will be slightly above the record low.
January precipitation was much below normal, while temperatures were typically above normal.
Storm systems had a tendency to split as they approached the Pacific Northwest. A lot of the energy associated with these systems dove southeast into the southwest United States or lifted northeast into British Columbia. Because storm systems were weak and starved for moisture as they impacted the region, precipitation totals were below normal.
Pacific Northwest mean temperatures departed +1.9 degrees from normal relative to 1961-1990 normals (31 stations). Mean temperature departures ranged from -6.0 to 9.2 degrees.
Several record high temperatures were broken or tied during the month of January. On the 2nd, the following records were broken: 70 at Brookings, 62 at Medford, 61 at North Bend, and 56 at Klamath Falls. On the 3rd, Great Falls tied a record High of 57. On the 4th, Eugene tied a record high of 63 and Astoria tied a record high of 59. On the 5th, Butte recorded a new record high of 50. On the 6th, Lewiston tied a record high of 57. On the 23rd, two record highs were broken in the Seattle area. Sea-Tac airport reported 56, while the National Weather Service Office in North Seattle reported 59.
No record low temperatures were tied or broken during the month of January.
No daily precipitation records were tied or broken during the month of January, but precipitation over the Northwest was the 5th driest on record since 1895.
For January, precipitation was:
36 percent of normal (1961-1990) at Columbia above Coulee,
51 percent of normal at the Snake River above Ice Harbor,
And 40 percent at Columbia above The Dalles.
For the water supply season, precipitation was:
56 percent of normal (1961-1990) at Columbia above Coulee,
76 percent of normal at the Snake River above Ice Harbor,
And 60 percent at Columbia above The Dalles.
Well below average precipitation impeded normal January snow accumulations. February first snow water equivalents range from 35 to 65 percent of normal in most areas. Snow water equivalent percentages dropped 5 to 20 percent from January 1st in most areas. The only exception was across southern Oregon, where snowpack percentages increased slightly. Snow pack deficiencies were greatest in Canada, where several sites are near the low of record for the February first date. Snow accumulations are also very deficient in the Washington Cascades, the Spokane drainage and on the Clearwater River in Idaho.
Observed runoff for January was extremely low ranging from 80-90 percent of normal on the Upper Columbia in Canada and the Upper Snake to between 20 and 30 percent on the Yakima and Spokane rivers. January adjusted flow for The Columbia River at The Dalles was 55 percent of average.
Deficient precipitation and snow coupled with dry soil moistures dropped the water supply volume forecasts down an additional 10 to 20 percent from January 1st. The January - July forecast for the Columbia River at The Dalles is 66.4 million acre-feet and 63 percent of normal, down 13 percent from January first. This compares to a runoff of 98.0 million acre-feet (maf) last year.