With temperatures forecasted to rise into the high 80s in the next few days, melting snowpack is expected to bring several northwestern Montana rivers and streams to flood stage by the end of this weekend, the National Weather Service officials said Thursday afternoon.
Temperatures throughout the Flathead Valley are expected to reach the low 80s on Friday and peak near 88 degrees on Saturday and Sunday, according to NWS meteorologist Bruce Bauck. “We’ll be reaching record high temperatures in several parts of the state this weekend,” he said. “It’s truly a very exceptional heat wave for this time of year.”
Those high temps are expected to cause rapid melting in what has been a persistent winter snowpack. Snowpack in the Flathead River basin was 133 percent of the 30-year average on Thursday, according to hydrologist Ray Nickless.
Forecasts indicate that several rivers in the northwestern area of Montana will approach or exceed flood stage by Sunday. The rivers include the Yaak River near Troy; the Fisher River near Libby; the North Fork of the Flathead near Polebridge; the main Flathead; the Middle Fork of the Flathead near West Glacier and Essex; the Stillwater River near Lawrence Park in Kalispell; the Swan River near Bigfork; and the Bitterroot River near Missoula.
In the Flathead Valley, the main stem of the Flathead River near Columbia Falls is showing the highest water levels; it’s predicted to the flood stage of 14 feet on Sunday and peak around 15.8 feet on Tuesday afternoon. The flow forecast for the Middle Fork Flathead River near West Glacier projects high water to reach around 11.2 feet on Monday, with flood stage being 10 feet. The North Fork Flathead River is projected to peak at 12.8 feet, just below the 13-foot flood stage.
Other exact predictions are available at the National Weather Service Web site, where the service will continue updates through the weekend.
“We’ll be making adjustments and updating as we go,” Nickless said. “Right now, it’s still hard to say exactly how the snowpack will react to this warmer weather – we could see it melt slower or faster than what we’ve predicted here.”
Temperatures in the area are expected to cool down by Tuesday of next week, but cooler weather could bring some precipitation, Bauck said.