Disaster officials advised communities in flood-prone areas of the northern Philippines to evacuate Saturday as the slow-moving Typhoon Koppu bore down on the coast with heavy rains and high winds.
Heavy rains are expected to inundate many areas on the main northern island of Luzon even before the typhoon makes landfall early Sunday, and 24 hours thereafter, acting weather bureau chief Esperanza Cayanan said.
Cayanan said that another typhoon farther east and a high pressure area north of the country will hold Koppu in a "semi-stationary" position and shroud most of Luzon with an enormous band of thick rain clouds.
President Benigno Aquino appeared on national television to warn Filipinos about the typhoon and appealed for cooperation to prevent casualties.
The typhoon was packing sustained winds of 160 kilometers per hour (100 mph) and gusts of up to 190 kph (119 mph) early Saturday about 300 kilometers (188 miles) east of Aurora, one of two provinces where it is forecast to come ashore. Forecasters expected sustained winds will reach 185 kph (116 mph) before it hits land.
"We are looking at the possible worst scenario, not to scare but to allow us to prepare," Cayanan said. "If it stays 24 hours ... and the downpour is sustained, we will surely have floods and landslides."
She said the typhoon's cloud band is about 600 kilometers (375 miles) across, unleashing the most intense rain close to the center.
"Your government is here in order to ensure that we will meet our goal of zero casualties," Aquino said Friday. "But I must emphasize (that) each local government unit, community, and Filipino that will be affected has the duty to cooperate ... to overcome the challenges ahead."
It was the first time Aquino has personally issued a storm warning on television since super Typhoon Haiyan barreled through the central Philippines in November 2013, leaving more than 7,300 dead and missing.
He said the Social Welfare Department estimates that 1.5 million families, or about 7.5 million people, will need relief assistance.
Metropolitan Manila, a sprawling urban area of 12 million, will be spared from the brunt of the typhoon but it is expected to be drenched with intense rain starting late Saturday, forecaster Adzar Aurelio said.
"Let us not wait to be told to evacuate," he said. "Let us evacuate and find the safe places."
Gabriel Llave, a disaster management officer of Aurora's Baler township, told ABS-CBN television they expect to complete "pre-emptive" evacuations by nightfall.
Civil defense chief Alexander Pama advised travelers to areas affected by the typhoon to postpone their trip. He said rescue units and relief supplies have been prepositioned near areas expected to suffer the worst from flooding and landslides.
Koppu will likely be equivalent to a Category 3 or 4 hurricane, according to AccuWeather Meteorologist Adam Douty.
Douty said 300-600 millimeters (12-24 inches) of rain is expected to be widespread on Luzon but certain areas could be inundated by over 900 mm (36 in.) that is "sure to trigger severe and life-threatening flooding and mudslides."
Koppu will be the 12th storm to hit the Philippines this year. An average of 20 storms pummel the country annually.