Hydrologists are beginning to warn residents about the likelihood of spring flooding with Northwest Montana’s snowpack approaching record levels.
The Flathead Basin snowpack was at 141 percent of average on Monday, with most mountain locations above 6,000 feet reporting more than 145 inches of settled snow.
The valley remains buried as well. West Glacier reported 38 inches of snow on the ground Monday, while Kalispell generally had 14 inches of snow. Locations in the north Flathead around Whitefish had about 2 to 3 feet of snow.
“For this time of year, we’ve got some pretty good low-elevation snow,” Ray Nickless, hydrologist with the National Weather Service in Missoula, said in a media briefing Tuesday.
He added that the potential for rain mixing with low-elevation melt could ramp up in the coming weeks as daytime temperatures climb above freezing. Colder nights, however, could aid in slowing valley melt off.
“We’ll keep an eye on that as we go through the spring,” he said.
Nickless said there is about a 70 percent chance the Flathead River will hit the 13-foot flood stage this spring. The Flathead River at Columbia Falls was at about 6 feet on Wednesday. The highest recorded peak of the river came during the floods of 1964 when it hit 25.6 feet.
“As the folks know up in the Flathead, it depends on when that water reaches that 13-foot level on whether it will be a big impact or not. It’s pretty easy to reach 13 feet on the Flathead when you’ve got this much snow accumulation.”
Nickless also noted the ample snow in the South Fork of the Flathead drainage, which feeds Hungry Horse Reservoir.
“That will be a good challenge for the [Bureau of Reclamation] ... to deal with all that water. It looks like they’re drafting down the reservoir nicely as we go thought the spring.”
Energy Keepers Inc., which manages the SKQ Dam in Polson, noted in a press release Wednesday that February natural flows into Flathead Lake were 160 percent of normal. The lake elevation is 2,884.9 feet, with the inflow at 11,000 cubic feet per second and the outflow at 12,500 cfs.
Energy Keepers said that as flood risk diminishes, it will start refilling the lake, with a target elevation of 2,890 feet by the end of May.
Long-range forecasts show above-average precipitation and below-normal temperatures lasting through May, which Nickless said points toward increased flood potential when it finally does warm up.
“It’s probably not a bad idea to start thinking about sandbags,” he said.