Typhoon BOPHA was formed in Marshall Islands. The latitude of its birthplace is around 4 degree north, whish is very close to the equator. Searching by Typhoon Birthplace Map, since 1951 there are only 13 typhoons born to the south of 5 degree north. The most recent one is Typhoon 200206, so this typhoon is the first in these 10 years. It is known that areas around the equator is where the typhoon is formed infrequently due to weak force (Coriolis force) for spiral motion.