Storms in the Philippines fall under four different weather classifications: Tropical Disturbance, Tropical Depression, Tropical Storm, and the Typhoon. A storm is classified a Tropical Disturbance when meteorologists observe poorly-developed wind circulation of weak velocities. A Tropical Depression occurs when there is a weak low pressure disturbance with a definite surface circulation, and maximum wind speeds are up to 25 miles per hour (63 kilometers per hour). A Tropical Storm occurs when maximum wind speeds are between 25-75 miles per hour (64-118 kilometers per hour), and this storm is considered a moderate tropical cyclone. The fourth category of storm is the Typhoon; A storm is considered a typhoon when its maximum wind speeds are above 118 kilometers per hour.