Wyoming Water Supply Outlook February 2020

NWS/NOAA Graphic

January 2020 precipitation totals across Wyoming were 95 to 105 percent of average. Precipitation numbers varied between 145 percent of normal over the Snake River Drainage (western Wyoming) to near 60 percent of average over the Clarks Fork Yellowstone/Shoshone Basin (northwest Wyoming). Current water year (October 2019 – January 2020) precipitation across Wyoming was 90 to 100 percent of average.

Mountain snowpack across Wyoming was 100 to 110 percent of median by early February. Snowpack “water” numbers were the highest across basins in north central Wyoming—varying between 130 to 145 percent of median. SWEs across basins in south central Wyoming (Sweetwater Basin) were 70 to 80 percent of median, and 110 to 130 percent in southeast Wyoming (North Platte Basin).

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

Wyoming reservoirs are averaging 75 to 85 percent of capacity in early February. Reservoir storages across Wyoming are above average at 120 to 130 percent for early February.