Forecasters discuss flood potential as melting begins

The National Weather Service on Wednesday warned that saturated soils, substantial high-elevation snowpack and possible rains in the coming week could lead to localized flooding in rivers and creeks throughout Northwest Montana.

The region has seen some of the highest levels of precipitation in recent months, and last month was Kalispell’s second-rainiest April on record. Weather Service hydrologist Ray Nickless said Wednesday that the current water year, which started last October, is on pace to be the wettest since record-keeping began in 1899.

More importantly, however, he noted that snow has continued to accumulate at high elevations in the region, setting up the potential for the Flathead River to reach minor flood stage in some areas.

“Now that we’re starting to get into this melt period, we’re going to start kicking that off here as soon as this weekend,” Nickless said in a conference call Wednesday afternoon. “... The rivers will just start slowly coming up, in the small streams as well, as we start coming through this melt period.”

As of May 1, high- and mid-elevation sites in the region still had about 126 percent of their normal snowpack, ranging as high as 134 percent of normal on Flattop Mountain in Glacier National Park and 142 percent of normal on Stahl Peak east of Eureka, according to federal data.

But Nickless noted that current mountain snowpack is similar to that seen in May 2011, when the region was spared from significant flooding impacts as the melting occurred more slowly.

Regarding the Flathead River near Columbia Falls, Nickless said, “We’re certainly headed above flood stage there just from snow melt, but how much higher are we going to be is really a function of how much rain we get.”

Streamflow forecasts compiled by the Weather Service on Wednesday showed the Flathead at Columbia Falls likely to crest late Sunday or early Monday at about 12 feet, with flood stage at 13 feet. The Stillwater River was expected to peak at about 7 feet in Kalispell, about a half-foot below flood stage.

In Lincoln County, Nickless said the Graves Creek area could see flooding in the coming days, with substantial snowpack remaining in its drainage in the Ten Lakes area.

He added that flooding along the Yaak River was “almost a sure thing,” particularly if substantial rain combines with high-elevation snowmelt.

Significant snowmelt on Thursday and Friday is possible, with temperatures forecast to reach into the low- to mid-70s throughout much of Western Montana. The mercury is expected to then drop back into the 60s over the weekend.

Reporter Sam Wilson can be reached at 758-4407 or by email at swilson@dailyinterlake.com.