An inversion that was holding smoke from a backcountry fire in Yellowstone National Park close to the ground prompted officials today to extend the closure of a section of the park's Grand Loop Road.

The "Antelope Fire," sparked by lightning around September 14, is located on the east slope of Mount Washburn and northeast of Dunraven Pass in the north-central section of the park. As of this morning it covered approximately 2,500 acres.

As a result of the smoky conditions, the section of Grand Loop Road between Tower and Canyon was to remain closed throughout the day and into the night, officials said.

The fire was burning in a section of Yellowstone that had burned during the fiery summer of 1988 and which now was covered with small stands of lodgepole pine and grasses.