WINTER WEATHER ADVISORY in effect for all mountain passes through early Monday morning for heavy snow and dangerous driving conditions. In general passes can expect between 4 and 8 inches with Lolo and Lost Trail passes having up to a foot of snow possible.
Mountain pass snow will be the biggest impact of the heavy precipitation expected over the weekend. Snow levels will be on the rise Sunday night. Low elevation passes like Lookout will see snow change to rain by Sunday morning. Valleys will see a good dose of rain. Higher elevations like Seeley Lake, Ovando, and Georgetown Lake will start out with snow overnight as well. Depending on how fast snow levels rise, these areas could see rapid snow accumulations as much as 5 inches before changing to rain on Sunday. Rain continues through the day around valleys in the region with highs in the upper 30s and low 40s.
Snow levels start to fall again during the day on Monday, but shower activity will be more scattered. Mountain snow will continue in Southwest Montana Monday with a chance for light snow in Butte and Bozeman by Monday evening. Tuesday will be largely uneventful with light showers around the state.
We remain on track for another potent system with much colder air reaching us between Christmas Eve and Christmas Day. Valley snow will be likely with this system.