A tornado is a violent rotating column of air extending from a thunderstorm to the ground. For a tornado to form, the area where the tornado forms must have these three ingredients: a lot of warm, moist air near the ground, atmospheric instability, and lastly clashing air fronts that act to propel moist air upward. There are three steps in the development of a tornado. The first step is that the first object that forms is a rotating body of air at the ground which happens because of vertical wind sheer. The second step involves horizontal rotating air that is lifted off the ground by the updraft of the thunderstorm. As soon as the horizontal air is lifted nearly vertically it is considered a mesocyclone. The final step in the development of a tornado is when the mesocyclone is fully developed in the updraft of a thunderstorm.
In the United States, most tornadoes travel from the southwest to the northeast which is because of an increased frequency of certain tornado-producing patterns.
Tornadoes rarely ever happen in Costa Rica. In the past 10 years, there have only been 3 tornadoes, each of which weren't very strong and quickly dissipated leaving minor damages along its path.
The United States experiences over 1,000 tornadoes each year although many go undetected and unreported. The Southeast and Midwest of the U.S. experience most of the tornadoes in the U.S. On the other hand, you would be lucky to see one tornado hit Costa Rica in a single year.
http://scienceline.ucsb.edu/getkey.php?key=1073
http://www.entercostarica.com/travel-guide/costa-rica-weather
By looking at this map, Costa Rica falls no where close to the "hot spots of tornado activity". Most the the tornado activity occurs in Europe and North America.
According to the graph, tornado occurrences appear to increase over time. This may not be all that accurate because the population of the world is increasing each year and for a tornado to be documented as a "tornado" someone must see the tornado. Also, tornado observation practices have led to more tornadoes being reported that otherwise wouldn't have been. Finally, improved technology most likely played a part in the increased number of tornadoes being reported.
Hurricanes
For a hurricane to form, there are three conditions that must be met. First, the ocean water must be warm enough at the surface. Second, atmospheric moisture from the water evaporation must combine with that heat and energy to form a powerful enough engine to propel the hurricane. Lastly, a wind pattern must be near the ocean surface to spiral air inward. Luckily for Costa Rica, they do not get hurricanes. Costa Rica is just a bit too far south so the weather patterns push the hurricanes up north. However, hurricanes north of Costa Rica can bring in heavy storms that can last for several days and may cause localized flooding.
Hurricanes are called by different names according to the region where the hurricane hits. In the Atlantic and East Pacific they are called hurricanes. In the Australia and near the Indian Ocean they are called cyclones. Lastly in Indonesia and off the coast of China they are called typhoons.
Hurricanes in the United States usually begin over the Sahara desert in Africa. It then moves over the Atlantic Ocean to build strength. Winds along the East Coast blow in a north or northeast direction. Also fronts or pressure zones may come into play where a hurricane travels.
Costa Rica do not experience any hurricanes. The United States however experiences about 6 hurricanes each year.
