Cooler spring weather increases flood potential

A stubborn snowpack is raising flood potential for western Montana's rivers and streams, a hydrologist with the National Weather Service said Friday.

"Most of the snow that's up in the mountains now, with a cool March and April, has been doing nothing but sitting there," said hydrologist Ray Nickless. "So we have some pretty high snowpack averages."

The Flathead basin's snowpack is at 119 percent of average for this time of year and the Kootenai basin's snowpack is at 125 percent of average. That's good news for alleviating drought conditions in some areas.

"The bad news is the longer that snowpack sits up there, the more flood potential we have in May and June," Nickless said. "Because that is our rainy season too."

Current streamflows are below average across Western Montana because of the lack of any runoff.

Nickless said the current conditions are highly comparable to 1999, when there was flooding on the Bitterroot River, the Yaak River, and in small streams in Lincoln, Ravalli and Mineral counties.

The National Weather Service has developed streamflow projections based on weather, snowpack and current streamflows. Nickless said the Whitefish, Stillwater and Middle Fork Flathead rivers are positioned to have flows approaching flood stage.

But those projections assume normal temperatures and precipitation.

"If we get above-normal temperatures and precipitation, we could see those rivers go above flood stage, especially if we get a lot of rain," Nickless said.

The weather this weekend has shown a warming trend, with mostly sunny skies and temperatures forecast to be in the 60s today. However, temperatures are expected to drop again by the middle of this week, which should further delay significant runoff.

"The more delays, the greater the flood potential is," Nickless said.

Reporter Jim Mann may be reached at 758-4407 or by e-mail at jmann@dailyinterlake.com