 Tilda attained its peak intensity of west of Guam on April 19, and it slowly weakened as it turned north-northeast and decreased in forward speed.The typhoon became quasi-stationary for 30 hours on April 20, weakening to a minimal typhoon in the process by the next day.After drifting under weak steering currents, Tilda accelerated to the north-northeast on April 22 and weakened to a tropical storm.