Typhoon Mawar bringing destructive winds and 'life-threatening' storm surge to Guam

The strongest tropical cyclone to impact Guam in decades is bringing "life-threatening" conditions to the U.S. island territory.

Typhoon Mawar's eyewall "clipped" the northern portion of Guam early Thursday local time, according to the National Oceanic and Atmospheric Administration.

The storm is bringing "destructive winds, a life-threatening storm surge and torrential rain" to the island, NOAA said.

Maximum wave heights of more than 40 feet were recorded near Guam amid the storm. The highest winds recorded on Guam were 105 mph before the anemometer broke.

The center of the typhoon passed about 15 miles to the north of Guam Wednesday evening local time. At that time Mawar’s maximum sustained winds were near 140 mph, equivalent to a Category 4 hurricane.

As the storm slowly moves away from Guam, the weather is expected to gradually improve on the island.

Most of Guam was without power by Wednesday afternoon, with the island's energy grid providing electricity to only 1,000 of its approximately 52,000 customers due to Mawar's "severe adverse conditions," according to the Guam Power Authority.

"We were able to avoid a complete island-wide blackout when the system severed into two grids," the agency said in a statement. "We are working hard to maintain the last remaining customers through the storm which contributes to quicker recovery after the winds die down later tonight or in the early morning hours."

An earlier forecast projected Mawar to hit the island as a super typhoon packing winds as strong as 160 mph -- equivalent to a Category 5 hurricane.

The National Weather Service has issued typhoon, extreme wind and flash flood warnings for Guam, which is the westernmost territory of the United States, located in Micronesia in the western Pacific Ocean.

Rainfall from Mawar could accumulate to as much as 20 inches on Guam, while the storm surge is forecast to reach as high as 25 feet. The typhoon was already producing waves up to 45 feet in the ocean near the island on Tuesday.

"Several inches of rain have already fallen," the NWS said in a bulletin on Wednesday. "Flash flooding is ongoing. Considerable flash flooding is likely, even for locations that do not normally flood."

Guam's Office of Civil Defense advised residents on Tuesday to seek shelter immediately, as Mawar is "expected to make a direct hit or very near passage for Guam."

"There is a potential of a catastrophic and devastating event for Guam," the office said in a bulletin.

Guam Gov. Lou Leon Guerrero also urged residents to take cover on Tuesday, as "damaging winds" were expected to start soon.

"Please take all the necessary precautions in an abundance of safety before we feel the full strength of the super typhoon," Guerrero said in a social media post.

President Joe Biden has declared an emergency in Guam due to Mawar and ordered federal assistance to support the response to the typhoon.

Mawar is one of the strongest typhoons to impact Guam since the 1960s -- the start of the satellite era.

The most destructive typhoon to hit Guam was Karen in 1962, with 155 mph winds and wind gusts of at least 170 mph, according to NOAA. Most homes on the island were destroyed.

More recently, in 2002, Super Typhoon Pongsona moved near the island with 144 mph winds and gusts up to 173 mph, causing $700 million in damage at the time, according to NOAA.

ABC News' Ahmad Hemingway contributed to this report.