Powerful typhoon Chaba barreled toward Japan's southernmost Okinawa island chain today, cancelling more than 300 flights. The violent storm is moving northwest near Okinawa, packing gusts of up to 306 kilometres per hour. <br/><br/>Japan's weather agency said, it also issued an emergency warning, its highest alert, suggesting the typhoon could be the strongest in decades and cause serious damage. With the storm closing in, authorities in Okinawa's capital Naha issued an evacuation advisory for its 320,000 residents. The storm is set to hit Japan's main island of Honshu later this week and then move through the Japanese archipelago.