JOHNSON CITY, Tenn. (WJHL) — Strong winds Monday night sparked a “spot fire” on the left flank of a 100-acre wildfire on Buffalo Mountain, but crews contained it, a forestry official told News Channel 11 Tuesday morning.

“Our pre-planning worked,” James Heaton of the Tennessee Division of Forestry said. “We were able to jump on it pretty quickly and connect some contingency lines that we had scouted and were able to draw a better rectangle around the fire.”

Heaton said he still expects the fire to be considered 100% contained within several days and that the judgment of 75% containment made late Monday afternoon was still accurate. Heaton’s fire crew used a bulldozer and worked until about 3 a.m. Tuesday, left the fire staffed and had another full crew come in at 7 a.m. Tuesday.

In addition to creating a better line, the crews working Monday night and early Tuesday used back burning to get rid of potential fuel should the main fire reach that area.

That left flank, on the south end of the fire, had been hand-dug the first day on the rocky soil that underlays the tree cover. Heaton said about 80% of the burned area contained mature hardwood trees.

“Our goal is to protect that hardwood at all costs,” he said.

That hardwood can also be problematic when conditions are favorable for fires. Fire can quickly reach the tops of trees.

“When you’ve got 70, 80, 90-foot trees burning from the top like a candlestick, sometimes there’s material we’re not able to catch and that’s what can cause situations like we had last night,” Heaton said. “It can be a stray ember, but a tree root or a stump can also be the cause.”

With weaker wind expected Tuesday, crews will be working to create what Heaton called a “perfect square” to keep the fire within its current bounds. A GPS mapping that may be complete Tuesday will give the state precise data on the boundaries and the size of the fire, which is estimated at 100 acres but probably grew some Monday night, Heaton said.

The wind is forecasted to pick up again Wednesday afternoon and be out of the east, which could push the fire toward Buffalo Mountain Park if crews can’t keep it within its current bounds. Some rain is expected starting early Thursday. Whether it will be enough to send crews off their watch by the weekend isn’t known.

“It’s really going to take a substantial amount of rain until it cools enough to not present a danger,” Heaton said. “We’ll be on it until that time comes.”

The cause of the fire remains under investigation. The initial call on the fire, around noon Sunday, came from Sutphin Road within the Johnson City limits and was answered by the Johnson City Fire Department.

Heaton said the fire began by consuming grass and brush and that a stand of kudzu complicated early containment efforts, helping allow the blaze to reach the bigger fuel on the mountain’s flank.