Hydrologic Outlook
Issued by NWS Portland, OR
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000 FGUS76 KPQR 132149 ESFPQR Water Supply Outlook National Weather Service Portland OR 2 PM PST Thursday January 13 2022 ...OREGON WATER SUPPLY SUMMARY AS OF JANUARY 13TH 2022... The water supply forecast for the spring and summer of 2022 is below average for most of southeast, central, and south-central Oregon. Forecasts are a mix of near-average and below-average for southwest Oregon, and forecasts are generally near-average for northwest and northeast Oregon. Most of the areas projected to be below average are already stressed due to drought conditions for much of the past 2 years. Precipitation so far this water year (October 1, 2021 to present) is highly variable around the state, ranging from above average for much of northwest and northeast Oregon and below average for central, southeast, and portions of southwest Oregon. Mountain snowpack increased drastically in December and early January for the Cascades, Blue, and Wallowa mountains and is above-average for almost all Oregon watersheds. Significant changes in conditions and water supply forecasts are possible through the rest of winter and early spring. Substantial precipitation and mountain snow accumulation is possible through April. However, long-term precipitation, snowpack, soil-moisture, and reservoir storage deficits will be difficult to overcome for the southern half of the state; much above-normal precipitation and snowpack will be needed to largely reduce drought impacts. Refer to the sections below and links provided for details regarding snowpack, precipitation, seasonal climate outlooks, reservoirs, streamflow, and water supply forecasts. The next update to this outlook will be issued by February 8, 2021. PRECIPITATION AND TEMPERATURES ACROSS OREGON Precipitation for the 2021 water year thus far (Oct 1, 2020 through Feb 4, 2021) ranges from 80 to 100 percent of average in Oregon. The lowest totals, 75 to 85 percent, relative to average have been in southwest Oregon, areas that have also been below-average for much of the past two years. The highest totals, 110 to 120 percent, have been in the northern Cascades and in portions of northeast Oregon. December precipitation ranged from 120 to 200 percent of average, with highest totals relative to average across much of northern Oregon. December temperatures were near to slightly above average. Snow levels during most of the heavy precipitation were relatively low, resulting in major snowpack increases in the Cascades, Blue, and Wallowa ranges. Details on precipitation and temperatures: NOAA National Weather Service - Northwest River Forecast Center www.nwrfc.noaa.gov/water_supply/wy_summary/wy_summary.php NOAA NWS - California-Nevada River Forecast Center (Klamath basin) www.cnrfc.noaa.gov/water_resources_update.php SNOWPACK ACROSS OREGON As of early January, mountain snowpack is above average statewide. Percent of average ranges from 105 percent in the Malheur basin in eastern Oregon to 170 percent in the Hood-Sandy-Lower Deschutes basin in north-central Oregon. Mountain snowpack was near zero in early December, but an active weather pattern and relatively cool temperatures in the latter half of December and early January resulted in major snowpack increases above 3000 feet elevation. Significant snow accumulation is possible through February and March, and even into April for northern portions of Oregon. Additional snowpack information: NOAA National Weather Service - Northwest River Forecast Center www.nwrfc.noaa.gov/snow/ USDA Natural Resources Conservation Service www.nrcs.usda.gov/wps/portal/nrcs/main/or/snow/ PRECIPITATION AND TEMPERATURE OUTLOOK The Climate Prediction Center produces monthly and seasonal outlooks, in which there is a weighing of the odds of near-normal, above-normal, or below-normal temperatures and precipitation. Due to ongoing moderate La Nina conditions in the eastern tropical Pacific, climate outlooks for February through April indicate an enhanced likelihood of below-average temperatures, with only a slightly enhanced probability of above-average precipitation for northern Oregon, with equal chances elsewhere. For late spring and early summer, the seasonal outlooks trend toward above-average temperatures and below-average precipitation. Visit www.cpc.ncep.noaa.gov for more about seasonal outlooks. RESERVOIRS Reservoir storage for most irrigation reservoirs across the state is much below average, with multiple reservoirs in central and southwest Oregon at record low levels coming into this water year. With carry-over storage from last water year so low, much above- average precipitation is needed through the winter and spring to build reservoir storage in support of late spring and summer irrigation demands. Owyhee Reservoir, the largest irrigation project in the state, has storage of about 130,000 acre-feet, 18 percent of capacity, as of early January. This is about 40 percent of average for this time of year. Reservoir storage will likely not change much through the winter, with the bulk of refill coming during spring snowmelt. Reservoir data is provided by the Natural Resources Conservation Service, the Bureau of Reclamation, and the US Army Corps of Engineers. Additional reservoir information: www.nwd- wc.usace.army.mil/nwp/teacup/willamette/ www.usbr.gov/pn/hydromet/select.html www.wcc.nrcs.usda.gov/basin.html OBSERVED STREAMFLOW Observed runoff so far this water year has been above average for rivers draining the coastal mountains of western Oregon, near average for the Willamette basin, and below average for basins elsewhere in Oregon. Runoff in December was near average in western and far-northeast Oregon and below average elsewhere. More recently, early January runoff is above average for most of northwest Oregon and near average for the rest of the state. Visit waterwatch.usgs.gov for details on observed streamflow. Runoff data is available at www.nwrfc.noaa.gov/natural/index.html at water year and monthly time scales for several locations in Oregon. WATER SUPPLY SEASONAL FORECASTS Water supply forecasts for April-September runoff volume are below average for most of the state, most notably for central and almost all of the southern half of Oregon. The only areas near average are northwest and far-northeast Oregon. The forecast for the Columbia River at The Dalles, which is a good index of conditions across the Columbia Basin, is 105 percent of average for April-September. Details on basin-scale water supply forecasts: NOAA National Weather Service - Northwest River Forecast Center www.nwrfc.noaa.gov/ws/ USDA Natural Resources Conservation Service www.wcc.nrcs.usda.gov/wsf/ $$

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Page last modified: 13-Jan-2022 9:49 PM
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