Flood Potential Outlook
Issued by NWS Portland, OR
Issued by NWS Portland, OR
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035 FGUS76 KPQR 062105 ESFPQR Water Supply Outlook National Weather Service Portland OR 205 PM PST Thursday June 6 2024 ...OREGON WATER SUPPLY SUMMARY AS OF JUNE 6TH 2024... The water supply forecast for the summer of 2024 is near average for most Oregon watersheds, with some notable exceptions. Water supply forecasts are below average for far-northeast Oregon and some watersheds in southwest and south-central Oregon. Water supply forecasts are above average for most of southeast Oregon, including the Owyhee basin. There were not major changes in seasonal water supply forecasts compared to a month ago. Precipitation so far this water year (Oct 2023 - May 2024) is near average for most of the state but above average for far-southwest and far-southeast Oregon and below average for south-central and far- northeast Oregon. Temperatures for the water year thus far are above average for most of Oregon except near-average for north-central and southeast Oregon. This is the last update for the season. Refer to the sections below and links provided for additional details and updates through the summer regarding precipitation, seasonal climate outlooks, reservoirs, streamflow, and water supply forecasts. PRECIPITATION AND TEMPERATURES ACROSS OREGON Precipitation for the 2024 water year thus far (Oct 2023 - May 2024) ranges from 80 to 110 percent of average in Oregon. The lowest values relative to normal are in far-northeast Oregon and the Klamath basin, and the highest are in southeast Oregon. May precipitation was below average for south-central, southeast, and far-northeast Oregon, above average for northwest and north-central Oregon, and near normal elsewhere. Temperatures for October through May were 1 to 3 degrees above average for almost all of Oregon, except near normal for the Columbia basin portion of north-central Oregon and much of southeast Oregon. May temperatures were 1 to 5 degrees below normal statewide except for near normal in far-southwest Oregon. 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 Westwide Drought Tracker Precipitation & Temperature graphics wrcc.dri.edu/wwdt/index.php?region=or SNOWPACK ACROSS OREGON As of June 5, mountain snowpack is completely melted for all but a few high elevation sites. Peak seasonal snowpack in the early spring was generally near average statewide. Additional snowpack information: NOAA National Weather Service - Northwest River Forecast Center www.nwrfc.noaa.gov/snow/ USDA Natural Resources Conservation Service nwcc-apps.sc.egov.usda.gov/imap/ 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. ENSO conditions are ENSO neutral as of early summer and are likely to transition to La Nina by autumn 2024. ENSO conditions have minimal impact on summer conditions but will likely have a major influence on the upcoming fall and winter. The outlook for June through August is for an enhanced likelihood of above-average temperatures and below-average precipitation statewide. Visit www.cpc.ncep.noaa.gov for more about seasonal outlooks. RESERVOIRS Reservoir storage for irrigation reservoirs across the state is generally above average, with most reservoirs completely or mostly filled as of early June. The main exceptions are reservoirs in southwest Oregon, where reservoir storage ranges from 55 to 75 percent of capacity. Flood control reservoirs in western Oregon are also completely or mostly filled as of early June. Owyhee, located in southeast Oregon, is the largest irrigation reservoir in the state. It has observed storage of about 713,000 acre-feet, which is 100 percent of capacity and 134 percent of average for this time of year. 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 most watersheds statewide, particularly so for watersheds in central and southweast Oregon. The only areas with below-average runoff are south-central and far-northeast Oregon. May runoff was generally near average statewide, except above average for some watersheds in western Oregon and below average for far-northeast and south-central Oregon. 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 near to below average for most of the state, except for above-average forecasts for southeast Oregon watersheds. The forecast for the Columbia River at The Dalles, which is a good index of conditions across the Columbia Basin, is 77 percent of average for April-September. Details on basin-scale water supply forecasts: NOAA NWS - Northwest River Forecast Center www.nwrfc.noaa.gov/ws/ NOAA NWS - California-Nevada RFC (Klamath basin) www.cnrfc.noaa.gov/water_resources_update.php USDA Natural Resources Conservation Service www.wcc.nrcs.usda.gov/wsf/ $$