Severe Weather in El Salvador

Tornadoes

There are three steps in the formation of the tornado.  In step one, vertical wind sheer causes a rotating body of air to form at the ground.  Next, horizontal rotating air is lifted off the ground by the updraft of a thunderstorm.  Once this horizontal rotating air mass is lifted vertically it is called a mesocyclone.  In the third and final step, the mesocyclone is fully developed in the updraft of the thunderstorm.  A funnel cloud is then formed from a narrow, fast rotating structure in the wall cloud; when this funnel cloud touches the ground it is referred to as a tornado.

In the United States, tornadoes usually travel southwest to northeast.  This is due to the fact that tornadoes form during intense thunderstorms, and thunderstorms normally travel in the southwest to northeast direction.  Most intense thunderstorms, and in turn tornadoes, develop in the Central Plain region ("Tornado Alley") because warm, humid air surface is overlain by cooler, drier air which produces an unstable atmosphere.  This unstable atmosphere helps to form large supercell thunderstorms and as a result, tornadoes as well.  

Tornadoes have occurred in El Salvador, but they are an extremely rare occurrence.  Tornadoes are a rare occurrence in El Salvador because of the country’s geographic location.  So many tornadoes occur in the central part of the United States because of its proximity to the Rockies (which forces dry line formation) and the Gulf of Mexico (which supplies low-level moisture).  El Salvador’s warm, tropical climate is not conducive for thunderstorm and tornado formation.  As a result, an average of 0 tornadoes occur in El Salvador p/year (http://www.ustornadoes.com/2013/07/25/from-domestic-to-international-tornadoes-around-the-world/ ) compared to the 1,523 tornadoes that occur in the US each year (http://www.ncdc.noaa.gov/oa/climate/severeweather/tornadoes.html) 

Add http://www1.ncdc.noaa.gov/pub/data/cmb/images/tornado/2010/annual/2010annual_torncount.png

According to the above graph, tornado occurrences have seemingly increased over time.  However, this might not necessarily be true because improved technology (Doppler radar, greater attention to tornado reporting, etc.) has allowed meteorologists and storm chasers the ability to record more storms than in previous years.  The above visual on "U.S. Annual Tornado Count" only takes into account the amount of tornadoes that are reported on a year-to-year basis.  As a result, the same amount of tornadoes may occur from year-to-year, but more may have been recorded in recent years.  Increased National Doppler radar coverage, increasing populations and greater attention to tornado reporting has all led to a rise in the number of reported tornadoes in the past decade.  As a result, these factors have created a misleading appearance of a growing trend in tornado frequency in the U.S.

Worldwide Tornado Frequency

http://web.gccaz.edu/~lnewman/gph111/topic_units/thunder_hurr/07_36.jpg

Hurricanes

In order for a hurricane to form, there needs to be warm ocean temperature (higher than 80F), a deep warm ocean layer more than 200 meters in depth, and the Coriolis effect is needed to initiate spinning (most hurricanes develop between 5 and 20 degrees latitude).  

The main hurricane formation regions occur in the Atlantic and East Pacific (where they are called hurricanes), in the Indian Ocean near Australia (where they are called Cyclones), and off the Coast of China and Indonesia (where they are called Typhoons).  

Hurricane Formation Regions

http://weatherdork.weebly.com/1/category/weather/1.html 

In the United States, hurricanes generally travel from east to west, but travel northward when they hit land.  Hurricanes form over the warm, tropical North Pacific and North Atlantic and are steered westward or northwestward by easterly winds.  These trade winds cause hurricanes to move east to west.  

Hurricanes do occur in El Salvador and travel in the same east to west direction that they do in North America.  El Salvador is located in Central America, nearby to both the Pacific Ocean and Caribbean Sea.   El Salvador is geographically located between 13 and 15 degrees N and between 88 and 90 degrees W.  Hurricanes form in the warm Caribbean Sea (to the east of El Salvador) and are pushed westward by trade winds.  The country's unique location (directly west of the Caribbean Sea) makes it fairly immune to the brunt of storms.  The trade winds rarely blow storms far enough west to make landfall in El Salvador.  Only 16 total hurricanes/tropical storms (less than 1 storm p/year) have ever made landfall in the country compared to the 1.78 hurricanes that make landfall in the United States p/year (http://www.aoml.noaa.gov/hrd/tcfaq/E17.html).  

Conclusion

El Salvador’s location in Central America and its warm, tropical climate contribute to its lack of tornado occurrence and in the sparse amount of hurricanes that occur.  El Salvador’s warm climate is not conducive for tornado formation, whereas in the central part of the United States, warm, moist air from the Gulf of Mexico and cool, dry air from the Rockies aid tornado formation. 

El Salvador is located to the west of the warm Caribbean Sea and is affected by hurricanes or tropical storms from time-to-time.  El Salvador is located in a unique region because the Caribbean Sea is located directly to the west of the country and trade winds rarely push storms westward enough to affect El Salvador.  As a result, El Salvador very rarely receives the brunt of the storm, but rather the outermost parts of it.  While hurricanes frequently pass by El Salvador, they do make landfall in the North American continent.  The United States’ location in the mid latitudes affects the generous amount of hurricanes that occur in the US.