SAIPAN – The western Pacific nation of Guam is on typhoon watch as a category three storm heads towards the country.

Typhoon Dolphin is due to hit the area from Friday afternoon local time, with wind gusts expected to reach 160 kilometres per hour.

The storm is currently located east-south-east of Guam and moving north-west at 12.8 kph.

A warning is also in place for Rota, Tinian and Saipan in the Northern Mariana islands.

Damaging winds of 62-91kph were expected there within 48 hours, Guam authorities said.

Typhoon Dolphin has already passed over eastern-most Kosrae and Pohnpei in the Federated States of Micronesia as a tropical storm.

Neville Koop, a meteorologist at Fiji’s Na Draki weather service, said the typhoon was expected to reach category three and pass very close to, or right over, Guam.

“It’s strengthening now after waffling around in the eastern part of the Pacific for a few days,” Koop told Radio Australia.

“Certainly it’s going to be much stronger by the time it gets to Guam – exactly how close it gets we’ll just have to wait and see.”

Koop said although Guam was located in an area prone to tropical storms, the nation had not had a typhoon make landfall for about 13 years.

He said the Pacific’s cyclone season this year had been unusual with storms occurring at times of the year they usually did not.

“You can put it down to the fact that there is a lot of warm ocean water in the northern Pacific right now,” he said.

“That heat has to go somewhere and nature’s most effective and efficient way of moving heat away from the equator is through a cyclone and that’s potentially what they do. So that would be the root cause of the problem.”

He said El Nino weather conditions could also be playing a part.

Typhoon Dolphin comes hard on the heels of Cyclone Pam, which devastated parts of Vanuatu, and Typhoons Maysak and Noul, which swept through FSM and the Philippines.

After passing Guam and Rota, Dolphin may continue to intensify, though it will probably not approach any more land masses.

Forecast models suggest the typhoon will curve north before being swept out into the open Pacific, by an eastward-moving mid-latitude trough.

Jeff Masters, director of meteorology at Weather Underground, says that the last typhoon to make direct landfall on Guam was category four Typhoon Pongsona in 2002.

“Sustained winds of 144 mph with gusts to 173 mph were recorded on the island at that time,” he said.

Surprisingly, there were no deaths directly due to Pongsona, despite the extreme conditions. Masters attributes this to the island’s strong building standards and typhoon experience.

Masters also notes that this is the earliest tropical cyclone to affect Guam since records began in the region in 1945.

The typhoon is also the earliest seventh named storm of the northwest Pacific season.

“Usually by this time of year, just two named storms have appeared – the seventh storm of the year typically doesn’t form until the third week of July,” Masters writes.

He also suggests the early start is due, at least in part, to extremely warm sea surface temperatures, which have been running higher than normal due to El Nino.