It will take weeks to fully assess damage a wind storm and following snowstorm did to Yosemite National Park. Downed trees in the Mariposa Grove did great damage to buildings there./NPS

It will be weeks before Yosemite National Park officials in California have a firm handle on how much damage was done by a last week's windstorm and this week's snowstorm.

The Mono wind event on January 19 blew down at least 15 sequoias in the park's Mariposa Grove, and caused extensive damage to buildings there and in the Wawona area that were pounded by falling trees.

"None of us have actually seen the damage as it is all closed and unsafe," said Frank Dean, president and CEO of the Yosemite Conservancy. "A Wawona resident said it felt like a tornado that lasted 8 hours. More trees coming down in Yosemite Valley recently from heavy snow."

Yosemite's chief spokesman, Scott Gediman, told local media that the Mono wind event, in which powerful winds dived off the Sierra and funneled down through the park, caused "millions and millions of dollars" in damage. On Friday, though, his office declined to put a dollar figure on the damage just yet.

At least 15 sequoia trees were downed by the Mono wind event on January 19/NPS

"Yosemite National Park continues, and will continue for several weeks, to assess the full extent of storm impacts and damage. We do not yet have a complete damage assessment or repair cost estimate," said Jamie Richards, Gediman's assistant.

As of Friday the plan was to keep the park closed to the public at least until Monday so crews could remove downed and hazardous trees and assess the damage. In the wake of the wind event a winter storm dumped more than 18 inches of snow on the Yosemite Valley, bringing down more trees.

"Heavy, wet snow has caused trees and branches to fall throughout the park, causing damage to park facilities and vehicles," said Richards. "There have been no injuries reported."

More than 18 inches of snow this week downed trees and did damage in the Yosemite Valley/NPS

When the park reopens, officials plan to keep it open 24 hours per day. Upper Pines Campground will open on February 8. Yosemite Valley Lodge and The Ahwahnee will open on February 5.

Day-use reservations will be required for all users, a park release said, including annual and senior pass holders. Each reservation is valid for seven days and must be validated the first day of the reservation.

Reservations will be available on www.recreation.gov beginning at 8 a.m. Monday, Feb. 1. Each day-use reservation is valid for one vehicle and the occupants of that vehicle. For more detailed information, please visit: https://www.nps.gov/yose/planyourvisit/covid19.htm

For visitors staying inside the park, at the Ahwahnee Hotel, Yosemite Valley Lodge or Upper Pines Campground, day-use reservations are included with overnight lodging reservations.

The reservation system will be in effect until local public health conditions improve.

Visitors will be able to enter the park using El Portal Road (Highway 140), Big Oak Flat Road (Highway 120 from the west), and Hetch Hetchy Road. Areas south of Yosemite Valley (including Badger Pass, Wawona, Mariposa Grove, South Entrance, and Wawona Road) will remain closed until further notice.