Wind River streamflow forecast slightly above normal for May

Wyoming NOAA Hydrologist Jim Fahey has shared the May 2020 Wyoming water supply outlook.

Below are items that Jim highlighted from the report as well as additional resources. You can read the entire report here: WY Water Supply – May 2020 Report



…Wyoming April 2020 precipitation was 75 to 85 percent of average…

…Current water year precipitation is averaging 90 to 100 percent of normal across Wyoming…

…Early May mountain snowpack across Wyoming is 85 to 95 percent of median…

Near normal (90 to 105 percent) snowmelt streamflow volumes are still expected across several major basins in Wyoming…

…Wyoming reservoirs continue to average 75 to 85 percent of capacity in early May…



April 2020 precipitation totals across Wyoming were 75 to 85 percent of average. Precipitation numbers varied between 135 percent of normal over the Snake River Basin (far western Wyoming) to 60 to 65 percent of average over the Powder and Belle Fourche Drainages (northeastern Wyoming).  Current water year (October 2019 – April 2020) precipitation across Wyoming was 90 to 100 percent of average.

Mountain snowpack across Wyoming was 85 to 95 percent of the median by early May.  Snowpack “water” numbers and/or SWEs were the highest across basins in northwestern Wyoming—varying between 105 to 115 percent of median.  SWEs across basins in south-central through southwestern Wyoming (Sweetwater, Upper Bear, and Lower Green Basins) were below 85 percent of median.

Near normal (95 to 105 percent) snowmelt streamflow volumes are still expected across several major basins in Wyoming.  Above-average snowmelt streamflow volumes are expected across portions of the Laramie, Upper North Platte, Shoshone, and Snake River Watersheds. The Sweetwater and Upper Green Basins, as well as portions of the Little Wind River Drainage, are still forecasted to have below-normal streamflow volumes during the upcoming snowmelt season.

Wyoming reservoirs are averaging 75 to 85 percent of capacity in early May. Reservoir storages across Wyoming remained above average at 105 to 115 percent for May. 

Other hydrological information for Wyoming can be found at the NOAA hydrology website

Monthly Wyoming Hydrologic Summary and Graphics (updated monthly around the 15th of every month)

Wyoming Drought Information Page (updated at least once a month)

Wyoming Graphical Water Supply Outlook (updated by the 10th of every month—January-June)

Wyoming Average Precipitation by Basin (updated monthly)

Wyoming Spring Snowmelt Runoff Flood Potential Graphic (updated around the 20th of the month—February-April—sometimes May)

Current and Forecast Wyoming Streamflows and/or River Stages:

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