Three wildfires burning across the Upper Peninsula covered an estimated 1,350 acres in Tuesday, Oct. 13, updates. Months of drought have allowed fire to burn deep into the forest floor, where it persists despite rainfall.

The Michigan Department of Natural Resources (DNR) updated the Ridge and Craig Lake estimates in its Oct. 13 bulletin. The Ridge Fire in Negaunee Township was estimated at 450 acres and was 20% contained. The Craig Lake Fire in Baraga County was an estimated 600 acres, also 20% contained. The Black River Fire in Gogebic County was estimated at 300 acres and 50% contained, according to WXPR’s account of a Tuesday evening Forest Service update.

Beth Fults, the DNR Incident Management Team's public information officer, said Tuesday that no structures faced immediate danger from any of the three fires. But the fire was also burning underground.

Drought conditions have left the forest floor so dry that fire is burning as deep as 2 feet into the duff layer, according to the DNR’s Oct. 13 bulletin. Duff consists of decomposing material between fallen leaves and mineral soil. The DNR warned that deep burning can damage roots, leaving apparently healthy trees unstable and liable to fall suddenly.

"These fires could be down two feet deep," Fults said in an Oct. 13 interview with WLUC.

Rain overnight Monday, Oct. 12, into Tuesday, Oct. 13, dropped about 1 inch on the Ridge Fire and roughly 0.6 inches on the Craig Lake Fire, according to the DNR. That slowed surface activity but did not extinguish the underground burning. DNR Incident Commander Nate Stearns said in the Oct. 13 bulletin that while rain helps, it also creates hazards for crews working in mud and on slippery exposed rock.

The DNR reported 53 firefighters on the Ridge Fire and 19 on the Craig Lake Fire, backed by a 19-person incident management team. Michigan State Police, the Marquette County Sheriff's Office, Baraga County Emergency Management and the Michigamme-Spurr Fire Department were providing additional support. Crews were hand-digging containment lines in terrain too rugged for bulldozers, according to Fults.

The U.S. Forest Service had transferred command of the Black River Fire south of Wakefield to the DNR, WXPR reported Oct. 14.

The DNR confirmed the Craig Lake Fire was caused by a lightning strike. Thunderstorms moved through the Upper Peninsula between Oct. 5 and Oct. 8, and a DNR pilot spotted the fire at 1:48 p.m. on Friday, Oct. 9. The Ridge Fire was spotted the same day at 3:55 p.m. Its cause remained under investigation in the Tuesday update.

Residents along North Basin Drive in Negaunee Township were under "Ready" status, the first tier of the DNR's "Ready, Set, Go!" evacuation system, according to the Tuesday bulletin. The Noquemanon Trail system west of the County Road 510 trailhead was still closed.

The DNR’s Tuesday bulletin reported temporary flight restrictions over Ridge and Craig Lake for a 5-nautical-mile radius below 3,500 feet. The DNR said drones are not permitted in the fire areas. The agency planned to deploy its own drones for aerial mapping once rain cleared, Fults said.

The DNR urges residents to check current burning restrictions before burning yard debris or starting a campfire.