Evergreen, MT Weather

Discussion

KEY MESSAGES:

- Mild day-time temperatures through Thursday.

- Patchy valley fog around sunrise each morning.

- Significant change coming Friday into the weekend.

A broad ridge of high pressure will continue to bring mild day- time temperatures across the Northern Rockies through Thursday. Stable conditions under the ridge are promoting the development of valley inversions and cold air pools, with observations the last few days suggesting high temperatures are struggling to reach their full warming potential. High cloud cover this morning into the early afternoon will limit solar heating, with temperatures feeling sluggish to warm until inversions weaken by mid-late afternoon. High clouds will generally decrease late afternoon as well, with plenty of sunshine for those looking to get outdoors.

Model guidance continues to advertise a significant change, as a trough and surface cold front tracks across the region Thursday night into Friday. The front will bring wind gusts of around 20 mph in Idaho and 20-35 mph across most of western Montana on Friday. Atmospheric moisture with this system will move northward the Great Basin, with precipitation focusing along and south of the I-90 corridor and along the Continental Divide in northwest Montana. The majority of the precipitation will fall within the warm sector of the trough, ahead of the approaching cold front, limiting the potential for winter weather impacts. Snow levels will fall to around 5,000 ft Friday and lower over the weekend as shower activity begins to decrease. Therefore, forecast snow amounts across the region are generally less than an inch, and mostly above 5,000 ft. The exception of course is the higher elevations of Flathead National Forest and Glacier National Park, which will likely pick up several inches of snow this weekend.

Aviation

Stable conditions will continue today under a ridge of high pressure. Valley inversions and cold air pools will set the stage for areas of valley fog, particularly near large bodies of water and river systems. The primary period to watch will be from 20/1200-1500Z, including Terminal KMSO. Fog can not be ruled out at KGPI as well, but the probability of impacts is less than 10 percent as high cloud cover has reduced overnight cooling.

Mso Watches

MT...None. ID...None.