MTPR

Heavy Snowpack Promises More Flooding In Western Montana

May 3, 2018

Western Montana’s flood waters receded a little bit Thursday, but it’s only a temporary reprieve. Warmer temperatures are on the horizon, and there’s more snowpack left in the mountains. Lots more.

Last week’s warm spell put a dent in some of western Montana’s low and mid-elevation snowpack. That led to the recent widespread flooding in places like Missoula, Seeley Lake, Lincoln and Helena.

But, “The real runoff hasn’t really even begun yet,” National Weather Service Meteorologist Genki Kino says.

That’s because there’s still an enormous amount of snow left in the higher elevations.

Temperatures will climb into the 70s starting Friday. Kino says this will melt more snow and trigger the next round of problems in the upper Clark Fork River, where a moderate flood stage is expected next week.

"Right now it has it reaching 12 feet around Wednesday or Thursday. There are numerous streets in (Missoula’s)that  Orchard Homes area that's going to be getting flooded,” he says.

The Bitterroot Valley has so far been spared any significant flooding. However, meteorologist Alex Lukinbeal points out some places in the south-central Bitterroot Mountains still have upwards of 55 inches of water equivalent left in the snowpack.

“When you have 55 inches of snowpack, you can almost imagine from now into mid-June to early July as getting 55 inches of rainfall onto the surface. That’s a lot of water that going to be put into the river system," Lukinbeal says.

River forecasts have the Bitterroot River near Missoula rising to minor flood stage by Tuesday night. The Bitterroot near Darby may approach record levels next week,  “with that 7.9-foot crest, with the record being 8.6 feet," he says.

Flood outlook for the Bitterroot River near Missoula.
Credit National Weather Service

Ongoing localized flood problems are anticipated in Seeley Lake and along low-lying areas along the Blackfoot River.

Natural Resources Conservation Service Water Supply Specialist Lucas Zukiewicz says the Bureau of Reclamation, anticipating an active flood season, has dropped Hungry Horse Dam by 70 feet on the south Fork of the Flathead River.

“So, there’s a bunch of room to take some of the edge off the Flathead specifically, but they have snowpack on this date which is above 180 percent of normal, and it hasn’t even started to move,” he says.

Earlier this week Governor Steve Bullock issued a statewide flooding emergency in Montana.

The order allows Bullock to mobilize state resources and the Montana National Guard to help during any qualifying emergencies.

On April 18, he issued an executive order declaring a state of emergency due to flooding in seven counties.