Hurricane Polo strengthens to Category 4, approaches southwestern Mexico

Hurricane Polo is strengthening as it moves north toward the southwestern coast of Mexico, where tropical storm conditions are expected later Wednesday.

Polo has maximum sustained winds of 250 km/h, making it a Category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale.

The National Hurricane Center says the storm is located about 300 kilometres south of Zihuatanejo and 540 kilometres southeast of Manzanillo.

Polo is moving north at about 4 km/h. A turn toward the northwest is expected later Wednesday, followed by a west-northwestward movement later in the week.

The hurricane's core is expected to remain offshore but pass near the southwestern Mexican coast during the next day or two.

A Tropical Storm Warning is in effect from Tecpan de Galeana to Punta San Telmo, while a Tropical Storm Watch extends westward from Punta San Telmo to Playa Perula.

The warning means tropical storm conditions are expected within 12 hours, while the watch indicates those conditions are possible within about 48 hours.

Heavy rain and flooding threat

Polo is expected to produce 75 to 150 millimetres of rain, with isolated totals of up to 200 millimetres, across coastal portions of Guerrero and Michoacán through Thursday.

The rainfall could cause life-threatening flooding and mudslides, particularly in areas of steep terrain.

Additional rainfall of 50 to 100 millimetres is possible along coastal portions of Oaxaca, Colima and Jalisco through Thursday.

Hurricane-force winds extend up to 65 kilometres from Polo's centre, while tropical-storm-force winds extend up to 165 kilometres.

The National Hurricane Center says fluctuations in intensity are possible, but Polo is expected to remain a major hurricane over the next several days.

Swells generated by the hurricane are also expected to affect parts of southwestern Mexico, potentially producing dangerous surf, rip currents and coastal flooding.