Typhoon Songda strengthened to a supertyphoon after battering the Philippines and headed for Japan on a track that may pass over the crippled Fukushima nuclear plant by May 30, a U.S. monitoring center said.

Songda’s winds increased to 150 miles per hour, the U.S. Navy Joint Typhoon Warning Center said on its website. The storm’s eye was east of Aparri in the Philippines at 8 a.m. today, the center said. Songda was moving northwest at 19 kph and is forecast to turn to the northeast and cross the island of Okinawa by 9 p.m. local time tomorrow before heading for Honshu.

The center’s forecast graphic includes a possible path over Fukushima Dai-Ichi plant, which has been spewing radiation since March 11 when an earthquake and tsunami knocked out cooling systems. Three of six reactor buildings have no roof after explosions blew them off, exposing spent fuel pools and containment chambers that are leaking.

“We are still considering typhoon measures and can’t announce detailed plans yet,” Takeo Iwamoto, a spokesman at Tokyo Electric Power Co., said by phone when asked about the storm. The utility known as Tepco plans to complete the installation of covers for the buildings by October, he said.

Japan is regularly buffeted by typhoons and tropical storms during the northwestern Pacific cyclone season. In 2004, eight cyclones passed over or skirted the country’s Tohoku region, where the Fukushima station is located, according to the Japan Meteorological Agency. The earliest was in May that year. The eyes of two storms passed within 300 kilometers of Tohoku last year, the agency’s data show.

Songda, the name of a branch of the Red River in Vietnam, is the fourth storm to form over northwest Pacific this year. The storm lashed the Philippines as it passed the eastern seaboard, leaving one person dead, according to the country’s disaster council. Songda prompted evacuations of coastal areas and caused flooding that jammed traffic and stranded travelers.

Damage to crops was “very minimal” as most had been harvested before the storm passed, Philippine Agriculture Secretary Proceso Alcala told reporters today.

The U.S. Navy Joint Typhoon Warning Center classifies storms as supertyphoons when their maximum sustain winds reach at least 150 miles per hour, according to the Atlantic Oceanographic and Meteorological Laboratory.