 The initial tropical disturbance formed near the International Dateline on October 10 before moving on a parabolic track well east of Asia . A small system , it moved west @-@ northwest and organized into a tropical depression on October 15 , then a tropical storm later in the day . Late on October 16 , Forrest intensified into a typhoon . The next day , the typhoon reached its peak intensity of 100 knots ( 190 km / h ) and passed near the island of Agrihan where one building was left standing and communications were eliminated . Forrest then recurved south @-@ southeast of Iwo Jima . As winds aloft increased out of the west , Forrest slowly weakened , becoming a tropical storm once more on October 20 and evolving into an extratropical cyclone by October 21 . 
