Wyoming Water Supply Outlook--May 8, 2019

Back-to-Back Pacific Storms to Impact the West Coast; Heavy Snow in the Central Appalachians

Back-to-back powerful Pacific storm systems to impact the Pacific Northwest and northern California through the end of this week with heavy rain, flooding, strong winds, and higher elevation mountain snow. A strong, long-duration atmospheric river will accompany the Pacific storms, bringing excessive rainfall and flash flooding to southwest Oregon and northwest California through the week. Read More >

HIGHLIGHTS:

…Wyoming April 2019 precipitation was 115 to 120 percent of average...

...Current water year precipitation is averaging 110 to 115 percent of normal across Wyoming…

…Mountain snowpack across Wyoming is 90 to 100 percent of median...

…Near normal to slightly above normal snowmelt streamflow volumes are still expected across several major basins in Wyoming…

…Total reservoir capacity across Wyoming continues to be 75 to 80 percent by early May…

SYNOPSIS:

April 2019 precipitation totals across Wyoming were 115 to 120 percent of average. Precipitation numbers varied between 160 percent of normal over the Snake and Upper Green River Drainages (west to west central Wyoming) to near 80 percent of average over the Big Horn River Basin (north central Wyoming). Current water year (October 2018 - April 2019) precipitation across Wyoming is averaging 110 to 115 percent of average.

Mountain snowpack across Wyoming was 90 to 100 percent of median by early May. Snowpack "water" numbers and/or SWEs were the highest across basins in western to northwestern Wyoming—varying between 110 to 120 percent of median. SWEs across watersheds in north central Wyoming were 65 to 80 percent of median.

Near normal to slightly above normal (95 to 105 percent) snowmelt streamflow volumes are still expected across several major basins across Wyoming. Above average snowmelt streamflow volumes are expected across the Shoshone, Upper Bear, Upper North Platte, and Laramie Watersheds. Several rivers and creeks along the Tongue and Powder River Basins are forecasted to have below normal streamflow volumes during the upcoming snowmelt season.

Total reservoir capacity across Wyoming continues to be 75 to 80 percent by early May. Reservoir storages across Wyoming remain above average at 115 to 120 percent for early May.

The latest Wyoming water supply outlook graphic: