El Niño is a weather phenomenon in the Pacific Ocean. It is “the warm water phases of the El Niño Southern Oscillation”  and is identified by the unique relationship between the Pacific trade winds and the ocean water in the Pacific Ocean.
Meaning of name
Fishermen off the west coast of South America noticed unusual changes in the fish population. The change in sea temperatures effected the environment of the marine life. Normally, fish are more comfortable in colder waters. As a result of the warming water, the fish began to relocate. Since this occurrence happened around Christmas, which is the day baby Jesus was born, fishermen referred to this phenomenon as El Niño, meaning the “Boy Child”.
This phenomenon is also referred to as “’El Niño-Southern Oscillation’”, or the abbreviation, ENSO.
The alternations in normal conditions in the atmosphere and sea are the driving sources for the formation of an El Niño. First, normal trade winds blow from the east to the west. During this process, winds move warm surface water into the western Pacific. As a result, a large pool is created near Indonesia. Now, the deep water in the eastern Pacific rises to the top as the warmer water moves out. The rising water is notably colder as it was deep below the surface, but it does begin to heat up. This area of cool water in the Pacific is known as the “cold tongue”.
El Niño conditions
Under the conditions of El Niño, the easterly wind speeds slow. As a result of the absent winds, the “cold tongue” warms to a higher temperature. The temperature rises 0.9 degrees Fahrenheit for three consecutive months. The large pool of warm water moves eastward during the summer and fall seasons, and temperatures continue to increase. At this point the water expands and sea levels rise.
The change in the sea-surface temperature affects the weather globally. When the water temperatures are warmer, moister rises into the air, which is the source for the occurrence of abnormal weather events. Some of the effects are flooding rains, warm weather, downpours, mudslides, mild winters and fewer hurricanes in different parts of the world.
Atmospheric changes in the United States
The warmer oceanic and atmospheric conditions are sources of energy for the jet stream. With warmer than normal conditions, the jet stream shifts east ward. This shift in the jet stream creates low and high pressures in different areas in and around the United States. Specifically, low pressure is found off the coast of Alaska and near the Gulf of Mexico, and high pressure forms over western Canada. During winter, the west and south eastern parts of the United States experience more precipitation while the northwest and Ohio Valley areas experience the opposite. In addition, the temperature conditions are warmer than average in the northern areas and colder than average in the southern areas of the United States.
Aside from the increase in storms, the weather phenomenon increases effective diseases such as Malaria in places that it normally does not occur. It is stated that Peru and Ecuador experience devastating shortages in fishing crops due to the warm water which is essential for fish to thrive. The impacts will vary from one El Niño to the next.
The occurrence of an El Niño is estimated to happen every two to seven years. The water temperatures and the strength and direction of the winds create the currents which determine the duration of the El Niño. 
Predicting El Niño
The warming of ocean temperatures in certain areas observed is used for predictions. Operations are carried out by the National Meteorological and Hydrological Services. The instruments involved in the process of observing and forecasting an El Niño are satellites, buoys, research ships and radiosondes. Satellites provide information on the tropical rainfall estimations and wind and ocean temperatures. Buoys provide data on “upper ocean and sea-surface temperatures”.
Current El Nino
The current El Niño that began in May 2015 will continue for several more months. Thus far, the series of weather-related disasters have been massive flooding in Paraguay, Madagascar and Zimbabwe and drought in Ethiopia. The year 1997 was the last time Earth experienced an El Niño this big. There are a few El Niño in the past that have set records. Currently, the El Niño of 2015/ 2016 is in the same class as the record setting El Niños.
Relevant online sources to this wiki article include:
- Encyclopedia of Earth El Niño
- National Geographic El Niño-Southern Oscillation (ENSO)
- NASA El Niño Global Impacts.
- USGA Coastal Change Hazards: Hurricanes and Extreme Storms
- NOAA El Niño Theme Page