By David Bailey
MINNEAPOLIS (Reuters) - An out of control wildfire has charred 100,000 acres of a northeastern Minnesota wilderness area popular for canoeing and camping, though cooler temperatures and some rain slowed its growth on Wednesday.
The new estimate of the scope of the fire's unprecedented growth from Monday to Tuesday came after a U.S. Forest Service flyover Tuesday afternoon gave a better view through the smoke, forest service spokeswoman Lisa Radosevich-Craig said.
"There was so much smoke that they couldn't get a good parameter of the fire line," Radosevich-Craig said.
The massive fire, now the biggest in the recent history in the Boundary Waters Canoe Area wilderness, left a smoke trail extending hundreds of miles to the southeast and prompted air quality warnings in Milwaukee and Chicago.
Radosevich-Craig said the fire had grown minimally since the big burst and minimal growth was expected on Wednesday. The fire has forced officials to clear 36 homes and warn residents to be ready to leave up to 100 others if it spreads more.
"They are being told be ready to go, gather your photos, gather your important papers, know where things are, but there are no evacuations that are expected for today or tomorrow," Radosevich-Craig said on Wednesday.
Cooler temperatures, a touch of rain overnight of about 0.1 inch that raised humidity slowed the spread of the fire, but some pockets may not be extinguished before winter snows that typically come in November, she said.
Carol Christenson, warning coordination meteorologist with the National Weather Service in Duluth, Minnesota, said winds were still breezy in the fire region on Wednesday, but were expected to diminish later Wednesday and Thursday.
"For the next few days we do expect winds to be a lot less," Christenson said.
Winds were still gusting from the northwest at up to 20 miles per hour on Wednesday, but were forecast to be 5 mph from the west on Thursday, she said. There were a few showers in the area on Wednesday and even a report of sleet, she said.
More than 230 firefighters are battling the blaze and another 200 are expected to reach the area today and Thursday, Radosevich-Craig said. Airplanes from Canada and four Minnesota National Guard "Blackhawk" helicopters have joined the fight.
Authorities were air-dropping equipment and water on the fire to slow its spread and cool it down so firefighters can enter, Radosevich-Craig said. On Tuesday, they focused in part on its origin, she said.
Known as the Pagami Creek Fire, the blaze started from a lightning strike on August 18 about 14 miles east of Ely, Minnesota, growing very slowly until strong winds and very dry conditions ignited a broad spread to the east on Monday.
More than 100 campers and hikers were cleared from the area over the weekend, some by float plane, and many wilderness entry points and roads have been shut down.
The fire is now the biggest by acreage in recent memory in the Boundary Waters. The Ham Lake Fire four years ago burned about 70,000 acres in the United States and Canada along the Minnesota-Ontario border.
Minnesota has seen much larger wildfires, including one that burned 1 million acres in the Red Lake area in the north central part of the state in the 1930s and a 350,000 acre fire around Hinckley south of Duluth in the 1890s.
(Editing by Greg McCune)