Fahey predicts normal runoff, cautions Wyomingites about significance of spring moisture

On Feb. 2, James Fahey, National Ocean and Atmospheric Administration (NOAA) hydrologist, released an early report analyzing hydrological factors leading to upcoming runoff forecasts in the state. 

In short, Fahey reported above normal snow water equivalents (SWEs) in central and western Wyoming by early February and above average soil moisture across basins in north-central through  northwestern Wyoming. 

“We see above normal base flows into late fall 2017 along rivers and creeks in central to western Wyoming, and reservoir storages across Wyoming are averaging 100 to 105 percent,” Fahey explained. “Above average snowmelt runoff volumes are expected across north-central through northwestern Wyoming.” 

The “Early Look Snowmelt Flood Outlook” produced by NOAA shows flood potential as moderate to high in northwest Wyoming with low snowmelt flood potential in the northeast, southeast and southwest corners of the state.

Soil moisture trends show above normal soil moisture in the northwest corner of the state and below normal in southeast Wyoming with normal soil moisture running from the northeast to the southwest corner of the state. 

Fahey also reported, however, SWEs in the snowpack is between 8,500 and 10,000 feet in elevation, significantly below levels seen in 2017 for basins. 

“However, SWEs are trending above normal in several basins, including the Upper Wind, Shoshone and Snake Headwater basins,” Fahey said. “Drainages along the western Big Horn Mountains also have above average SWEs for this time of year.”

“Although is too early to make definitive predictions on the magnitude of the upcoming runoff, several key hydrological ingredients should cause above average runoff volumes across north-central through northwestern Wyoming,” he emphasized. 

However, in making his forecast, Fahey also said  the magnitude of the spring and early summer runoff is highly dependent on the amount of moisture Wyoming receives during the late March through early June time frame – especially for basins east of the continental divide. 

Visit wrds.uwyo.edu for the latest maps and data related to water supply in Wyoming. Saige Albert, managing editor of the Wyoming Livestock Roundup, compiled this article. Send comments to saige@wylr.net