722 FXUS65 KMSO 232049 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 149 PM MST Mon Dec 23 2013 .DISCUSSION... A quick moving cold front will cross the area tonight, causing some noticeable changes across the Northern Rockies in the next 12-18 hours. Light precipitation has continued in many areas ahead of the front, but as this is in the relatively warm air ahead of the front, snow levels have been on the increase. Thus, after some morning flirtations with mixed rain/snow/freezing rain, impacts have generally been on the decline. However, the front itself will reintroduce some travel impacts, namely snow and areas of blowing snow to the passes and higher terrain. Advisories suggesting problematic travel at times have been left for many of the passes, and also the travel corridor between Seeley Lake and Swan Lake. The front will have the greatest impact on the northern Bitterroots and northern Continental Divide (Lookout, Lolo, Marias Passes) early this evening, then move to the southern Bitterroots (Lost Trail Pass) mid to late evening. Many of these areas already have snow covered roads, but the concern with the front will be two to three hours of poor visibilities due to increased snow intensity and blowing snow. Precipitation in the valleys will change from a mix of rain and snow to snow after the front passes, but it is also expected to diminish rapidly behind the front. Thus, valley travel corridors could see some slick surfaces at times, but widespread impacts are not expected. On the Camas Prairie...a good pattern for strong pre-frontal winds near Grangeville will persist until the front passes mid evening. Temperatures over the next couple days will be noticeably cooler, particularly at night. In fact, minimum temps Wednesday morning may be up to 20 degrees colder than what we woke up to this morning. After Christmas...mountain temperatures and the high valleys such as the Butte/Pintlar region will warm, with the lower inverted valleys remaining colder. A disturbance will bring colder air aloft to the area by Friday night, which will help mix the inversions, along with some light snow. The coldest conditions with that system, as well as the best chance of snow, will be for areas closer to the Continental Divide. && .AVIATION... Temperatures and snow levels have gone up ahead of an inbound cold front. This front will cross northern Idaho and northwest Montana early this evening (00Z-03Z), then west central Montana and Lemhi County, Idaho mid to late evening (03Z-06Z). Showers will be numerous ahead of and with the front, but will become more scattered after it passes. Visibilities will be reduced at times as the precipitation changes over to snow. Gusty surface winds could cause blowing snow, causing further visibility issues. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...WINTER WEATHER ADVISORY until 5 AM MST Tuesday Lower Clark Fork Region...West Glacier Region. WINTER WEATHER ADVISORY until 5 AM MST Tuesday Bitterroot/Sapphire Mountains...Potomac/Seeley Lake Region. ID...WINTER WEATHER ADVISORY until 4 AM PST Tuesday Southern Clearwater Mountains. WIND ADVISORY IN EFFECT UNTIL 7 PM PST THIS EVENING FOR THE CAMAS PRAIRIE...GRANGEVILLE AND HIGHWAY 95. && $$ Whitmore/Gibson Follow us on Facebook and Twitter! https://www.facebook.com/US.NationalWeatherService.Missoula.gov https://www.twitter.com/NWSMissoula