Severe Weather in Zimbabwe

Tornadoes are a type of severe weather that forms in a very unique fashion. The formation of tornadoes always occurs during a thunderstorms, during permitting conditions. Because of increasing wind speeds at higher altitudes and drag and friction caused by the surface (vertical wind sheer), a rotating body of air known as a vortex tube forms along the surface of earth. This horizontal column of air is lifted up and vertically by the warm updrafts of a thunderstorm and a "mesocyclone" forms. When this mesocyclone is fully developed in the updraft of a thunderstorm, it is now a tornado. Tornados in the United States travel in a northeast direction because this is the direction of the prevailing westerlies that affect most of the continental US. Very rarely do tornadoes occur in Zimbabwe because of it's unique location and how it is being shielded by Madagascar from the direct path of the NE trades. The average number of tornadoes that occur yearly in the US is 1253 (http://www.ncdc.noaa.gov/climate-information/extreme-events/us-tornado-climatology). The average number of tornadoes that occur yearly in Zimbabwe is hard to find, most likely because there is not a very high chance of running into a tornado in Zimbabwe.

http://www.ncdc.noaa.gov/img/climate/research/tornado/globdist.jpg

Although Zimbabwe is very close to a tornado hotspot over South Africa, it avoids these tornados and steers clear of this 'hotspot" because of Madagascar off the coast of Africa and how it blocks and diverts the prevailing wind direction, which would be where most of the tornados are coming from.Though tornado occurrences appeared to have increased over time, this may not be entirely true  because in the last 30 years, the methods that have developed in detecting and accounting for tornadoes have greatly improved. Because of this instead of the number of tornado occurrences going up, maybe it's just the number of tornadoes able to be detected has risen.

The three main requirements for a hurricane is : 1) warm ocean temperatures, at least 80 degrees fahrenheit or higher, 2) deep warm ocean layer (200 m deep, only occurs <20 degrees latitude) and 3) Coriolis effect to start the rotation (needs to occur within 5 degrees latitude of the equator). The three regions in which hurricanes occur is: 1) in the Atlantic and East Pacific (called hurricanes) 2) in the Indian Ocean near Australia (called cyclones) 3) off the coast of China and Indonesia (called typhoons).

http://spaceplace.nasa.gov/hurricanes/en/cyclone_map_large.en.gif

The general direction of Hurricanes in the US is normally in an eastern direction following the westerlies, though usually the hurricane starts off moving in a western direction because this is the direction of the trade winds where the hurricane originated. The general path of the hurricane follows the directions of the prevailing winds in the area. From it's place of origin up until the continental US, the wind direction completely flips, which gives hurricanes the appearance of changing directions. Again, hurricanes do not occur often or at all in Zimbabwe because of it's special location behind Madagascar, being shielded from the general direction of the wind and the path of the hurricanes. On the other hand, the United States averages 5.8 hurricanes per year, according to NOAA.