Guam's governor set Condition of Readiness 1 to begin at 1 p.m. Saturday ChST (11 p.m. Friday ET) as Typhoon Champi approached, the Pacific Daily News and The Guam Daily Post reported. At COR 1, destructive winds are possible within 12 hours, the Pacific Daily News reported, citing the Joint Information Center. Guam had been in COR 2 since Friday afternoon, the Post reported.

Gov. Lou Leon Guerrero urged people in southern, coastal and flood-prone areas to move to safer shelter, the Pacific Daily News reported. "The south is going to be severely impacted. The coastline is going to be inundated," she said, according to the paper. She urged residents to stay off the roads once COR 1 takes effect and to stay out of the water, saying the Coast Guard may be unable to do sea rescues at the storm's peak, the paper reported.

Champi was upgraded to a typhoon with top sustained winds of 85 mph as of 7 a.m. Saturday ChST (5 p.m. Friday ET), the National Weather Service in Guam said in Advisory 10. It was about 340 miles east-southeast of Guam, moving west-northwest at 15 mph, and is forecast to strengthen through Monday, the advisory said. A weather service update at 10:44 a.m. ChST (8:44 p.m. ET) said Champi is forecast to pass just south of Guam as a Category 3 typhoon.

Brandon Aydlett, science and operations officer at the weather service office in Tiyan, said rapid intensification has begun, according to the Post. "We're looking at an intensifying Category 3 typhoon as it passes near Guam," he said, according to the Post. Damaging winds should begin after sunset Saturday, and destructive winds could start around sunrise Sunday, followed by typhoon-force winds, Aydlett said, according to the Post. Conditions should improve quickly Sunday afternoon and evening, the Post reported.

A typhoon warning is in effect for Guam and Rota, and Tinian and Saipan are under a tropical storm warning and a typhoon watch, the weather service said. The weather service expects 12 to 20 inches of rain on Guam, waves up to 35 feet and 5 to 7 feet of coastal flooding, the Post reported. Most metal-roof homes on Guam will be severely damaged, and power outages could last several days to weeks, the weather service said in an early Saturday statement, according to the Post.

What we know: Champi is a typhoon forecast to pass just south of Guam on Sunday as a Category 3 storm, and Guam's COR 1 was set to begin at 1 p.m. Saturday ChST.
What we don't: How strong Champi will be at its closest approach, and how much damage it will cause.