Large portions of the Columbia River and Puget Sound watersheds were impacted, including the Portland, Yakima, and the Palouse region.

[5] Prolonged cold settled in following the heavy snow, causing the ground to freeze throughout much of the Columbia Basin and surrounding valleys.

La Niña conditions with a ridge of high pressure over the Rocky Mountains and an Aleutian Low helped to drive the moisture into Washington and Oregon rather than into California.

[7][8] With soils in many places either frozen or saturated, water resulting from rain falling on snowpack was unable to seep into the ground, instead remaining on the surface causing flooding.

It is estimated that flood control infrastructure in the Willamette Valley prevented additional damage around $1.1 billion (1996 value) in Portland alone.

[16] About 11 inches (280 mm) of rain fell on the east side of Snoqualmie Pass in three days, causing the Yakima River to rise.

Similar values were recorded near the headwaters of the Naches River, a tributary of the Yakima, with most communities from Nile in the Cascade Mountains to Toppenish taking damage.

Visitors to a country club in Yakima were stranded when an ice jam blocked the river and cut off access, requiring military vehicles to be used in the evacuation.

Interstate 82 near Granger was closed for flooding, and sediment entering the Naches River from one of its tributaries forced the closure of State Route 410.

[5] U.S. President Bill Clinton visited Boise, Idaho and the greater Portland area to tour flood damage and meet with both victims and local officials.