The National Weather Service in Missoula is forecasting that a wet Pacific system will continue to impact the Northern Rockies through Monday night, March 10, bringing widespread precipitation in the form of valley rain and mountain snow.

The latest model runs indicate that a wide band of moderate to heavy precipitation will develop later tonight over Idaho, Clearwater and northern Lemhi counties in Idaho, moving into Ravalli, Granite, Deer Lodge, Powell and Silver Bow counties in Montana.

“The two concerns will be hydrologic issues from the additional rainfall and snowfall over several mountain passes and even into Butte on Monday morning,” the Weather Service warns. “Confidence in potential for flooding is high, but only moderate confidence in locations of flooding.”

Northwest Montana over the past 24 hours has received 0.5 to 1.5 inches of rain from the first surge of moisture. The rain should be dissipating through Sunday evening.

After midnight Sunday and into Monday morning, another plume of moisture, but significantly weaker, will move through Northwest Montana, resulting in an additional 0.1 to 0.5 inch of rain.

“The area has been dealing with widespread poor water drainage from the snow melt and previous rainfall,” the Weather Service said. “This additional rain will just further contribute to these issues, so a flood advisory continues for Lincoln, Mineral, Sanders and Flathead counties into Monday.”