GENERAL OUTLOOK

The 2002 water supply season has started out well. Both precipitation and snowfall have been above to well above average this Fall and early Winter. Soil moisture deficits from last years near drought will diminish spring runoff somewhat.

A stormy weather pattern that developed in late November across the Pacific Northwest continued across the region through the early and middle part of December. A series of storm systems moved across the region, bringing frequent periods of valley rain and mountain snow to the Pacific Northwest, especially to areas west of the Cascades. A drier scenario set up late in the month as a ridge of high pressure developed, causing low pressure systems to weaken as they approached the Western United States.

The 31 station temperature index for the Pacific Northwest departed +0.6 degrees from normal relative to the 1971-2000 normals. Mean temperature departures ranged from -4.8 to 4.3 degrees.

For December precipitation was:

90 percent of normal (1971-1990) at COLUMBIA ABOVE COULEE,
111 percent of normal at THE SNAKE RIVER ABOVE ICE HARBOR,
and 98 percent at COLUMBIA ABOVE THE DALLES.

For the water supply season, precipitation was:

91 percent of normal (1971-1990) at COLUMBIA ABOVE COULEE,
110 percent of normal at THE SNAKE RIVER ABOVE ICE HARBOR,
and 104 percent at COLUMBIA ABOVE THE DALLES.

PRECIPITATION SUMMARY

Daily precipitation records established in December included: 0.89 inches at NOAA Sandpoint (Seattle), 1.55 inches at Bellingham , 1.63 inches at Sea Tac Airport, 2.12 inches at Olympia, 2.36 inches at Hoquiam, and 2.63 inches at Stampede Pass on the 13th and 1.88 inches at Stampede Pass, 2.10 inches at Hoquiam, 2.10 inches at Port Angeles, 2.90 inches at Olympia, and 3.44 inches at Shelton on the 16th.

SNOW SUMMARY

The 2002 snow accumulation season has started out very well, especially for areas west of the Cascades. Snow water equivalents on January 1st range from 200 percent of average in Oregon to 150 percent in Washington. East of the Cascades the northern areas and the Upper Snake have average water equivalents while southern basins have percents mostly from 90 to 130. This compares to January 1st snow water equivalents of 70 to 90 percent of average in water year 2001.

RUNOFF

Except for the Cascade drainages in Washington, Fall and Winter runoff have been below average. Streamflow has ranged from 40 to 80 percent of average. Low runoff is due to well below average Summer and Fall precipitation, but also very dry soil conditions following the near drought of 2001.

The precipitation and snow water equivalent conditions mentioned above lead to a slightly below average runoff percents for water year 2002. The forecast volume for the January - July period at The Dalles is 98.7 million acre-feet or 93 percent of average. This compares to a runoff of 58.2 million acre- feet in water year 2001.