Dense Fog in Eastern Roosevelt, Montana

Multiple episodes of dense fog with visibility of a quarter mile or less occurred at the Big Sky Field Airport AWOS (KS85). The first episode lasted for 7 3/4 hours from the early morning to late morning on the 2nd. The second episode lasted 8 3/4 hours from the early morning to the late morning of the 3rd. The third episode lasted 21 hours from the late afternoon of the 3rd to the early afternoon on the 4th. The last episode lasted 4 1/2 hours from the early evening to the late night on the 4th.

Areas of dense freezing fog formed over northeast Montana, with the river valleys of the Milk, Missouri and Yellowstone Rivers being most prone for development.