In the National Weather Service’s final flood outlook of the season, hydrologist Jim Fahey assigned the highest flood potential in the state to the Laramie area this spring.
Because of the substantial snowpack for the Laramie Basin and northern Colorado supply, Fahey’s expecting “moderate to high” flood potential for the lower portions of the Laramie watershed.
As of Monday, the Laramie Basin’s snowpack sat at 114 percent of its median for this time of year. The South Platte Basin in Colorado, which also fuels Laramie, had 110 percent of its median snowpack Monday.
The flood risk is exacerbated by the fact that the National Oceanic and Atmospheric Administration is expecting Wyoming to get more rain in the next three months than it usually does.
In fact, Wyoming’s chance of exceeding its median rainfall is higher than any other state.
Fahey told the Laramie Boomerang that Laramie’s flood risk is generally highest from May 21-June 10 each year.
“It could come a little sooner than that if we get the rain,” he said.
Fahey said he highest flood risk would come if there are multiple hot days followed by heavy rain.
“That’s the double whammy that we don’t want to see. That would really bring the water down into Laramie quickly,” Fahey said. “But all you really need is three days of really warm temps.”
At the start of this week, it was Wyoming’s counties along the state’s southern and western borders that had the most impressive snowpack.
While Laramie has the highest flood risk, Fahey’s also assigned “moderate” flood potential to the rivers near Saratoga and Baggs.
All other headwater basins have low flood potential.
At the beginning of 2019, Laramie already had decent chances for flooding, and those chances have only grown after southeast Wyoming got 170 percent of its median precipitation in March.