“Tropical Weather”

by Caleb, KE0FOE

As we continue with our series covering JetStream, The National Weather Service’s new Online School for Weather, the topic this time is: Tropical Weather.

Virtually all tropical weather relies on close proximity to the equator. However, there is one type of tropical weather system which usually cannot form within 5 degrees latitude north or south of the equator.

Tropical Cyclones, also known as Hurricanes and Typhoons depending on where they occur, usually cannot form very close to the equator. This is because the Coriolis force, which causes storms to spin, is very weak at the equator. Therefore, in order to get the needed rotation, tropical storms usually must form more than 5 degrees latitude north or south of the equator.

There was one exception though. Earlier this century, Typhoon Vamei formed near Singapore on December 27, 2001. U.S. Naval ships were able to record a maximum sustained wind of 87 m.p.h. along with a  gust up to 120 m.p.h. While this was happening, Typhoon Vamei’s center of circulation was only at latitude 1.5° North. This means that Typhoon Vamei’s circulation was on both sides of the equator!

Oh, and by the way, at 1.5 degrees north latitude, Typhoon Vamei, did spin counter-clockwise like all storms north of the equator do.

There are a lot of interesting facts about Derechos that you and your family can learn about on the National Weather Service’s new Online School for Weather called JetStream. Visit their website: weather.gov/jetstream