It’s going to be a wet weekend in Northwest Montana.

Precipitation is expected to start late this afternoon and will continue through Monday with up to 0.7 inches of rain falling in the Flathead Valley. 

As much as 1.5 inches of rain could hit Libby and Thompson Falls and 3 inches are possible in the Cabinet Mountains.

“This is a very wet system for this time of year; we’ve got a plume of moisture coming all the way from Hawaii. The heaviest time frame looks like it’s going to be on Sunday,” said Genki Kino, a meteorologist with the National Weather Service office in Missoula.

Drivers should watch out for standing water on the roads and stay alert for rock slides and debris flows when driving next to steep terrain, particularly along U.S. 2. Kino cautioned those who have to drive to take it slowly and report any debris on the road to the highway patrol. 

The recent warm spell is expected to mitigate the likelihood of slides.

“Usually at this time of year we have some snow that’s been melting and it loosens up the soil, so if we had a good snowpack year the ground would already be loose with that melting snow,” he said. “It’s going to be more the intensity of the rain that will cause issues.”

A weak cold front will begin pouring over the Continental Divide Sunday night, resulting in more high-elevation snow than was previously forecast. Snow is expected at altitudes above 4,000 or 5,000 feet, with the heaviest snowfall occurring Monday.

Most of that precipitation will occur in the West Glacier and Marias Pass areas, with 2 to 5 inches possible. Minor snow accumulations are likely farther south and west in the Swan Range and Seeley Lake areas. 

However, Kino said the cold front is harder to pin down in advance.

“There’s still a lot of inconsistencies on how much of that cold air is going to spill over the Divide,” he said.

Whitefish Mountain Resort will likely see some snow at higher elevations, with mixed precipitation down toward the village area. The Flathead Valley could see some mixed snow and rain as temperatures drop overnight.

Since water levels are generally low right now, no flooding issues are expected on rivers or creeks, although smaller streams receiving the heaviest precipitation will likely run high for a couple days.

Reporter Samuel Wilson can be reached at 758.4407 or by email at swilson@dailyinterlake.com