Avalanche warning issued; rivers expected to rise

Heavy, blowing snow and rain prompted a backcountry avalanche warning Monday for mountain ranges across Northwest Montana.

The Flathead Avalanche Center in Hungry Horse issued the warning through 6:30 a.m. Tuesday, alerting that the avalanche danger was elevated to “high” Monday.

For areas on and below steep slopes at all elevations, the warning spans Flathead, Lake and Lincoln counties including the Whitefish, Flathead and Swan ranges, as well as the Lake McDonald, Stevens Canyon and Marias Pass areas in Glacier, according to the center.

“Very dangerous avalanche conditions are developing,” the center said Monday morning. “Traveling in and below avalanche terrain is not recommended. Avalanches may run long distances and entrain wet snow at lower elevations as more rain and snow fall.”

A strong weather system brought dense snow, wind and rain to mountain locations overnight Sunday into Monday, a recipe that could overload buried weak layers in the snowpack.

Places like Tunnel Ridge in the Flathead Range reported 10 inches of new snow Monday morning, with half falling within a two-hour period.

Freezing levels were forecast to climb to roughly 6,000 feet in elevation throughout the day.

Elevations above the freezing level could get up to 2 feet of snow. Meanwhile, rain on snow in locations below the freezing line will create a “wild card” in the avalanche forecast, the Avalanche Center warned.

“Wet avalanches are very likely once the rain begins to wet the surface,” the Monday avalanche forecast stated. “We can not rule out the possibility of wet slabs failing if liquid water reaches buried crusts, facets, or surface hoar that exist 1 to 3 feet below the surface.”

Generally, avalanche conditions were moderate or low prior to the storm.

“We’ve been fortunate to have generally safe avalanche conditions recently; now it is time to tune it way back and head to low angled slopes free of overhead hazard,” the Avalanche Center advised.

MEANWHILE, VALLEY locations will likely see rain through Thursday as high temperatures rise into the mid 40s and lows stay above freezing.

“While the most intense precipitation this week will fall [Monday through Tuesday], precipitation is here to stay over the Northern Rockies through much of this week under moist southwesterly flow,” the National Weather Service stated in its Monday forecast.

Area rivers and streams are forecast to rise due to rain and snowmelt, especially in the far reaches of Northwest Montana near Yaak and Troy.

The Weather Service notes that projections have the Fischer River near Libby reaching action stage by Wednesday afternoon.

“To reach this stage, flows on the Fischer River in cubic feet per second would have to increase ten-fold from current flows,” the Weather Service forecast warned. “The Yaak River near Troy will also jump considerably between now and Wednesday, with flows also projected to increase by about a factor of ten.”

However, it’s not likely either of these streams will reach impactful levels.

A cold front is poised to reach the region by the weekend, dropping snow levels back to the valley floor. Lows in the teens and highs in the 30s are probable.