NWS Says ‘Atmospheric River’ Bringing Rain and Snow to Region

Western Montana is experiencing what meteorologists call ‘an atmospheric river,' as a large area of moisture in the form of rain and snow is now affecting the area.

Meteorologist Joe Messina described the system now bringing rain to the valleys and snow to the high mountains.

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“At the lower elevations we're going to get some rain,” said Messina. “Basically, it’s a warm front associated with this atmospheric river. This atmospheric river is a continuous plume of moisture that extends from where we're at here in the Northern Rockies out to the Pacific Ocean and its pumping moisture through the atmosphere in our area and that's creating some precipitation.”

KGVO asked about the effect of the system on the mountain snowpack.

“Depending on the elevation, it's going to be a boost to the snowpack,” he said. “It depends on where you are, too. “Really the favored ranges for this particular event are going to be the Kootenai and Cabinet ranges up in northwest Montana as well as the Bitterroot and Clearwater ranges closer to home. The Glacier Park region will do pretty well, but not quite as well as those other areas. You're going to have to get up to, you 6,000 to 7,000 feet once we get into later on today and tonight, for it to be snow at all.”

Messina said there’s little danger of flooding due to the rain, but streams and rivers will rise, nonetheless.

“Streams are going to be on the rise for sure,” he said. “I mean, if you're occupying areas near waterways and you're used to the winter river levels, those are going to be on the rise here in the next few days, so be prepared for some rising streams. Now again, this isn't going to be a dangerous situation or a flood situation, but it will definitely be a change.”

Messina said the higher mountain passes are experiencing snow, but even that will turn to rain as temperatures rise.

“If you're driving up Lolo Pass, Snowbowl or Lookout Pass you'll experience some snow today,” he said. “Again, that is also going to start to transitioning more towards rain. Now, towards the end of the week, we do have another system that we'll be watching that's going to bring some colder air back in. So yeah, I'm not taking my snow tires off, that's for sure.”

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