NOTE: This story has been updated ... read the latest report here.

LATEST UPDATES, WEDNESDAY MORNING

- The McHugh Fire burning just south of Anchorage is now estimated to be 400 to 600 acres. That figure differs from Tuesday estimates in part because the steep terrain and thick smoke have made it difficult to determine the precise size of the wildfire, said Division of Forestry spokeswoman Sarah Saarloos.

- The fire is estimated to be 1.1 miles from Potter Marsh and 1.3 miles from Rainbow subdivision as of this morning, according to Saarloos. Those estimates are the same as yesterday.

- No evacuations have been ordered. Last night fire officials saw a "slight decrease in fire behavior," Saarloos said.

"There is still such a potential threat, not just to the community of Rainbow but it’s running parallel to the Seward Highway," she said.

Any evacuations would be announced on Anchorage police and fire community alerts,

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- Both lanes of the Seward Highway were open to traffic as of Tuesday night, according to the Department of Transportation.

- As firefighting efforts continue, a community meeting is scheduled for 7 p.m. tonight at South High School.

FULL STORY:

A large wildfire is burning uncomfortably close to two residential areas at the edge of Alaska's largest city, and emergency officials in a Tuesday evening news conference say heavy winds and steep terrain are complicating firefighting efforts.

What sparked the human-caused blaze overnight Saturday near McHugh Creek is unknown, but the fire is now estimated at 350 acres, slightly less than a previous Division of Forestry estimate that was inflated due to thick smoke. Approximately 1.1 mile from the fire's southwestern boundary is the 17-home Rainbow Subdivision, and 1.3 miles from the northern boundary is Potter Valley, the beginning of the densely populated South Anchorage hillside.

"Zero containment," Tom Kurth, leading an inter-agency team battling the blaze, said of the fire's status to media late Tuesday. "If we get winds blowing up through that area again, we're liable to have a new perimeter by morning."

By Wednesday morning, a couple hundred firefighters are expected to be on scene, including five hotshot crews. Also contributing to the growing logistical challenge are dozens of specialists from the state Department of Transportation, Division of Forestry, Anchorage Fire Department, Anchorage Police Department, Alaska State Troopers, and Alaska National Guard.

Chugach State Park trails are closed, and all day long, traffic screeched to a halt on Seward Highway, the lone road connecting Anchorage and Kenai Peninsula communities. Traffic began to flow in both directions at 9 p.m., but traffic delays should be expected indefinitely. Kurth says there is fire activity at the edge of the road in the area around milepost 111, and drivers should beware of rocky debris spilling from the craggy hillsides.

Good news may be on the horizon later this week, with heavy rain forecast as very likely throughout the day Thursday.

But for now, bad news is the focus: heavy westerly winds are expected throughout the evening, potentially pushing the fire's boundary increasingly close to Rainbow Subdivision, a small community that sits along a dirt road and is composed of 17 homes, as well as tough terrain.

"This is very steep, rugged country, about 45 percent slopes up there," Kurth said, adding that fires like this typically grow uphill, and this one is acting as expected. "The first area that would be threatened would be in the Rainbow area ... so that is where the structure protection is taking place."

Because of the terrain, air support will play a critical role in the firefighting effort. Two air tankers and multiple helicopters have been battling the blaze out of Girdwood and South Anchorage, said Division of Forestry spokeswoman Sarah Saarloos.

Even with the ominous sight of smoke billowing over Turnagain Arm, no evacuation orders are in effect, though Rainbow and South Anchorage residents who live near Potter Marsh have been warned to be ready to leave their homes at a moment's notice.

"Everyone is holding their breath," said Bob Childers, president of the Rainbow Valley Homeowners Association.

David Hamre, a Potter Valley resident, was joined by nearly a dozen friends Tuesday evening to clear trees and brush from the area around his home.

"Our friends just show up. Isn't that amazing?" Hamre said, adding that his family is going through the tough process of prioritizing what to take if they need to leave. "Pictures, jewelry, and for us musical instruments. The other stuff is just going to have to take its chances."

Others in the area were staging hoses and sprinklers around their homes.

"It's still nerve racking" said Aaron Huey of Potter Valley. "There’s a lot of spruce in the area. We built the house two years ago, I’d hate to see it go away."

The fire was moving about 50 feet per hour toward Potter Marsh on Tuesday afternoon, according to AFD assistant chief Alex Boyd, and state health officials graded the air quality in the area anywhere from moderate to very unhealthy.

Still, “people are being remarkably calm," Childers said. "Many have put together a carload of stuff. We’re just kind of hanging out.”

Fire officials will host a public meeting Wednesday at 7 p.m. at South Anchorage High School.