Fire managers with the Flathead National Forest are monitoring a 43-acre wildfire in the Bob Marshall Wilderness that was first spotted Tuesday near Three Sisters Creek, but are currently allowing the small blaze to run its natural course.

The fire was caused by lightning.

“It’s in a high-elevation, remote part of the Bob Marshall Wilderness, and not expected in any way to grow near the Bob Marshall Wilderness boundary,” said Seth Carbonari, the fire management  officer for the Spotted Bear Ranger District. “It’s well over 13 miles from the boundary, so it would have to travel quite a ways to offer any threat to anything outside of the wilderness.”

The Three Sisters Fire is burning between two structures: the Pentagon Cabin in the Spotted Bear Ranger District and the Rock Creek Cabin in the Lewis and Clark National Forest’s Rocky Mountain District.

“Our plan right now is the point protection around the cabins, if it becomes necessary, and to allow the natural fire its ecological role,” Carbonari said.

Most of the blaze’s growth from an initially reported two acres to its current estimate of 43 acres occurred Tuesday, as it was fanned by dry, high winds. A drop in wind speed and spike in humidity Wednesday kept the fire activity low, and Carbonari noted that continued high humidity will likely keep it from growing significantly.

The Flathead Forest is conducting a couple of reconnaissance flights each day and communicating with the Beartop Lookout in the Lewis and Clark National Forest to monitor the fire’s progress. Carbonari said it is mostly burning in alpine fir and has natural barriers that will likely restrict its growth. Located between areas burned during the 2012 Red Shale and Wall Creek fires, much of the terrain is rocky and sparsely vegetated.