Humidity dropped to 11 percent Tuesday and caused more active burning at the Chrandal Creek forest fire 42 miles south of Darby.

The Bitterroot National Forest Wednesday update set the size of the lightning-caused fire at 2,300 acres as some unburned areas on the northwest side felt the flames.

Fire lines are remaining secure on the southeastern corner and the fire is still listed as 40 percent contained.

A column of smoke (see photo) was visible Tuesday afternoon, and fire managers think that will happen again this week as the temperatures stay high and the humidity stays low. They're expecting fire activity on the west side of the fire and hotshot crews are also working on the fire edge at the head of Mine Creek.

Five helicopters have been helping the ground crews by dropping water on hot spots. There are twelve 20-person crews on the lines, along with six engines, a dozer and eight water tenders.

Closures remain in effect and only residents and firefighters are allowed on the Hughes Creek Road.