Deluge raises rivers, adds to snowpack

A steady downpour over the last couple of days has added to mountain snowpacks and raised flows on Northwest Montana rivers, some of which were expected to approach flood stage by today.

“Right now, most of the river response we’re seeing is because of rain,” said Jeff Kitsmiller, a meteorologist with the National Weather Service in Missoula.

A total of 1.58 inches of rainfall was measured at Glacier Park International Airport over a 24-hour period ending at 2 p.m. Wednesday.  

Low temperatures and new snow at higher elevations have increased mountain snowpack above the Flathead Basin to 139 percent of average. Snowpack above the Kootenai River Basin is 140 percent of average.

The automated snow gauge at Noisy Basin in the Swan Mountains recorded 3.9 inches of new precipitation over a 24-hour period ending Wednesday afternoon.

The moisture first fell as rain and then as snow. The total snowpack at Noisy Basin is 69 inches with water content of 30.4 inches.

On Flattop Mountain in Glacier National Park, an automated snow gauge recorded 1.3 inches of new precipitation in 24 hours ending at 10 a.m. Wednesday. Current snowpack at Flattop is 97 inches with a water content of 43.4 inches.

The recent weather has hampered snowplowing work on Glacier’s Going-to-the-Sun Road.

At the end of last week, two avalanches crossed the road, forcing the west side crew to plow its way out to return to park headquarters.

While plows were able to work Tuesday on clearing the Logan Pass parking lot, crews were forced to do road work at lower elevations on Wednesday because of winter weather on the alpine stretch of Sun Road.

“Since we have that amount of snow in the mountains, we’ll probably have a big runoff once it warms up,” Kitsmiller said.

For this week, the Yaak River near Troy was expected to slightly exceed minor flood stage today. Flows from Libby Dam were reduced significantly to prevent flooding on the Kootenai River in the area of Bonners Ferry, Idaho.

Rivers in the Flathead Basin have risen significantly this week.

The Flathead River at Columbia Falls, for instance, has risen by more than two feet in the last couple of days.

The Middle Fork Flathead River at West Glacier has gone up three feet over the same period.

Today in Columbia Falls, the National Weather Service and the U.S. Geological Survey will unveil a sign denoting the high-water mark that the Flathead River reached during the massive 1964 flood.

That year, the river peaked on June 9. The sign will be unveiled near the dead end on South Nucleus Avenue at 1 p.m.

In 1964, the Flathead River at Columbia Falls crested at 26 feet.

By comparison, the river is expected to crest today at 13.3 feet, just below flood stage of 14 feet.

Some relief is in sight for soggy Flathead Valley residents, according to the Weather Service.

Today there is a 20 percent chance of showers, with showers (but not heavy rain) expected to continue into the weekend.