The new water year (started on Oct. 1) has seen highly variable rain and mountain snowfall catches. The seasonal rain/snow accumulation graphic (below) suggests higher than normal totals in the north Oregon and Washington Cascades, northeast Oregon, southern Idaho, western British Columbia, and western Montana, while below normal in central/southern Oregon.
Ocean and atmosphere indicators suggest we are in a moderate La Niña event where Pacific Northwest winters are colder than normal temperature, above normal rain/snow. This means that the amount of spring snowmelt runoff will be moderately above normal. The timing of the runoff could be a little late this year due to colder than normal mountain temperatures. This runoff feeds the river flow which helps the fish migrate down the river and out to the ocean. North Pacific Ocean conditions along the coastlines are more favorable for salmon survival now due to enhance coastal upwelling from the deep ocean.
The figure (below) shows the current state of the region’s snowpack. The north Oregon and Washington Cascades basins are looking good, even with the recent four-week dry spell. Current snow level is at 2000 feet. We are past the half-way point in the seasonal accumulation of PNW snowpack. The effects of the flash drought (March-Sept. 2021) are slowly being erased.
Snowpack, along with monthly and seasonal precipitation and current river flow, are the key components that are used to calculate the seasonal Water Supply Forecast. This forecast is used by water management agencies – U.S. Army Corps of Engineers, BPA, and the U.S. Bureau of Reclamation – to determine how much water is released for power, irrigation, and fish.
The latest CRITFC water supply forecast (as of February 18): Columbia River at The Dalles is 118% of normal for the April-July runoff period. NOAA’s forecast is 94%.
Update provided by Kyle Dittmer, CRITFC Hydrologist-Meteorologist
Charts provided by NOAA/National Weather Service, updated on 18-Feb-2022.