A fire in Yellowstone National Park near the northwest shore of Yellowstone Lake on Friday prompted officials to close the Grand Loop Road.

The fire, in combination with a major road construction project between Madison Junction and Norris, has blocked all routes to the north end of Yellowstone from Grand Teton National Park and Jackson Hole. The fastest route to Mammoth Hot Springs likely would entail taking Highway 191 north to Bozeman, Mont., then heading south to Livingston, Mont.

Called the Arnica Fire, the blaze cloaked Jackson Hole in smoke Friday after it grew to more than 250 acres. Officials say the lightning-caused fire is burning in lodgepole pine about five miles west of the Bridge Bay Campground. Fire personnel are monitoring the blaze and “actively managing small areas of concern,” according to a statement.

Officials say helicopters will drop buckets of water on the southern and western portions of the blaze to keep it away from power lines in the area as well as the Grand Loop Road. Winds are moving the fire southwest, and the blaze is expected to grow as the conditions persist.

“A substantial amount of the smoke we’re experiencing in Jackson Hole is related to the Arnica Fire burning near West Thumb in Yellowstone National Park,” said Jackie Skaggs, spokeswoman for Grand Teton National Park. “It’s unusual for us to get [winds from the north]. We’ll probably continue to get increasing amounts of smoke from those areas.”

While public health officials were unavailable Friday evening, they have said in the past that valley residents should use caution during outdoor activities when fires are active.

Fire management officials said Friday that the Lower Gros Ventre Prescribed Fire, which Teton Interagency Fire personnel started earlier this month, grew 175 acres since Thursday, moving over a ridge and into Tent Creek for a total of about 1,395 acres. Officials hope to eventually burn about 2,700 acres to benefit wildlife including bighorn sheep. Skaggs said personnel have stopped actively igniting the blaze.

“They were just letting it continue to burn ... making sure that it stayed within the prescription.”

While the Lower Gros Ventre burn has put up a lot of smoke, fire officials don’t think the fire is putting much smoke into Jackson Hole, Skaggs said.

“Most of that smoke was headed south along the Gros Ventre Mountains,” she said.

The Bradley Mountain Prescribed Fire, a half mile east-northeast of Alpine, was last reported at 3,042 acres.

“They’re actively igniting that today,” Skaggs said Friday. “I think the smoke from that went totally away from us.”

The Ditch Creek Fire north of Kelly was holding at 30 acres Friday despite the recent spell of brisk afternoon winds.

In Grand Teton National Park, the Bearpaw Bay Fire near Jackson Lake had grown to 130 acres Friday afternoon and prompted closures of backcountry campsites at Bearpaw Bay, Trapper Lake and the east shore of Leigh Lake. The fire was still burning within the boundary of the 1981 Mystic Isle Fire.

“We’re still monitoring the Bearpaw Bay Fire,” Skaggs said. “We don’t have anyone out there trying to influence where it goes. We’re not doing any active fire suppression activities. We want that one to burn for resource benefit.”

Skaggs said the backcountry campsites closed as a result of the Bearpaw Bay Fire likely would reopen within the next several days.

“We’ll continue to keep those closed for a few days until the wind shifts and takes the fire and the smoke to the northeast,” she said.

The Third Creek Fire, which officials at one point thought was mostly extinguished, is burning on 6 acres.

“It has a little bit of heat, but it hasn’t been actively flaring up,” Skaggs said. “There was no smoke visible [Thursday]. It’s not actively burning.”