Patricia has continued to strengthen overnight and has maximum sustained winds of about 185 miles per hour, or 295 km per hour, WMO spokeswoman Clare Nullis told a U.N. briefing in Geneva.
The US National Hurricane Center, meanwhile, called Patricia the strongest eastern north Pacific hurricane on record.
It said the storm will make a potentially catastrophic landfall later Friday in southwestern Mexico.
The center said Patricia has grown into a Category Five storm in the five-level Saffir-Simpson scale, with maximum sustained winds of 325 kilometers (200 miles) per hour.
"Some fluctuations in intensity are possible today but Patricia is expected to remain an extremely dangerous category 5 hurricane through landfall," the center said in a bulletin issued at 0900 GMT.
"An extremely dangerous storm surge is expected to produce significant coastal flooding near and to the right of where the center makes landfall," the center added.
Forecasts show that Patricia will make landfall in the western state of Jalisco, near the neighboring state of Colima.
The region includes the major port of Manzanillo in Colima and Jalisco's tourist resort of Puerto Vallarta, which Mexican officials said could face a direct hit.
Some businesses boarded up their store windows in Manzanillo as rain began to fall in the city.
"Better be safe than sorry. Hurricanes are unpredictable," said Enrique Esparza, manager of El Gran Mueble furniture store, which is near the seafront.
Rosa Elba Figueroa, a housewife, left a supermarket with a bag full of canned tuna, powdered milk, bread, water and batteries.
"We're running home to put wood and tape on the windows," she said.
Jose Maria Tapia Franco, director of the National Disaster Fund, said 400,000 people live in vulnerable areas but that local authorities will decide whether to conduct evacuations.
At the beach village of Boca de Pascuales, authorities took 70 people to a shelter while another 30 drove to the homes of relatives further inland.
"We are patrolling communities on the coast in the Puerto Vallarta area as well as Melaque and La Huerta, urging the most vulnerable population to get to safety," Jalisco state civil protection director Jose Trinidad Lopez Rivas told Foro television.
SCHOOLS, PORTS CLOSED
Mexican officials closed schools in Jalisco, Colima and Guerrero states.
Two dams in Jalisco and Michoacan were being drained to prevent flooding.
Ports closed to small boats in several ports in the states of Jalisco, Nayarit, Michoacan, Guerrero and Oaxaca. The port of Acapulco in Guerrero was shut for larger ships.
At 0900 GMT, Patricia was 255 kilometers south of Manzanillo and moving northwest at 19 kilometers per hour, according to the US forecasters.
Patricia is expected to produce eight to 12 inches (20 to 30 centimeters) of rainfall over the states of Jalisco, Colima, Michoacan and Guerrero, which could produce flash floods and mudslides, the US center said.
The Mexican water commission warned that rivers could rise and roads could be affected by the bad weather.
WIND FORCE SPARKS CONCERN
Officials said nearly 1,800 shelters for 259,000 people are available.
"The amount of water and the strength of the wind worry us," national civil protection coordinator Luis Felipe Puente told a news conference.
Jalisco, Michoacan, Colima and Nayarit are expected to get the equivalent of 40 percent of their annual rainfall in the next 48 hours, the water commission said.
Mexico faces the double threat of Atlantic and Pacific tropical storms during the hurricane season, which ends November 30.
In 2013, twin storms Ingrid and Manuel nearly simultaneously struck each coast, leaving 157 people dead in a rare double onslaught. With reports from Reuters and Agence France-Presse
source: www.abs-cbnnews.com
