El Niño & La Niña (El Niño-Southern Oscillation) | NOAA Climate.gov El Niño & La Niña (El Niño-Southern Oscillation) LA NIÑA ADVISORY La Niña continues, but a transition to ENSO-neutral is expected to occur by February, with ENSO-neutral continuing through the first half of 2017. More ENSO status information ENSO Monitoring at the Climate Prediction Center El Niño and La Niña are the warm and cool phases of a recurring climate pattern across the tropical Pacific—the El Niño-Southern Oscillation, or “ENSO” for short. The pattern can shift back and forth irregularly every two to seven years, and each phase triggers predictable disruptions of temperature, precipitation, and winds. These changes disrupt the large-scale air movements in the tropics, triggering a cascade of global side effects. More about El Niño El Ni&#241o and Southern Oscillation El Ni&#241o and its Effects Diagram showing the principle of the El Ni&#241o in the central Pacific. Colors indicate temperature, with red being warmest and blue coldest.

In normal, non-El Ni&#241o conditions (top panel of schematic diagram), the trade winds blow towards the west across the tropical Pacific. These winds pile up warm surface water in the west Pacific, so that the sea surface is about 1/2 meter higher at Indonesia than at Ecuador. During El Ni&#241o (bottom panel of the schematic diagram), the trade winds relax in the central and western Pacific leading to a depression of the thermocline in the eastern Pacific, and an elevation of the thermocline in the west, thereby bringing an end to nutrient upwelling . (From: NOAA). For more information on El Ni&#241o go to: Scripps Institution of Oceanography El Ni&#241o - A Definition Unusual rainfall in Southern California � and in Peru and Chile � are commonly tied to a climatic condition that involves the entire Pacific and is referred to as "El Ni&#241o." The term, as applied to climate, originated with fishermen in Ecuador and Peru who used �El Ni&#241o� to mean the �Christ Child� as a way to describe a warm current that appears every few years in their fishing areas, around Christmas.

What exactly is meant climatically by saying, "We have an El Ni&#241o situation?� Normally, the cold Peru Current (or Humboldt Current) flows offshore from south to north. (It is a kind of mirror image of the California Current, but colder and stronger.) Associated with this cold current is a process called " coastal upwelling ," or the rising of cold subsurface water. This upwelling water is rich in nutrients ( nitrate and phosphate). These nutrients stimulate the growth of microscopic green algae ( phytoplankton ), which then serve as food for small animals ( zooplankton ). The plankton is eaten by fish (mainly anchovies and sardines), which are in turn caught by bigger fish, sea lions, birds, and people. During an El Ni&#241o situation, when the warm current appears, upwelling ceases and phytoplankton production is greatly diminished and the fish move to colder regions farther south (or they starve). El Ni&#241o � A Larger Picture The appearance of the warm current off Peru is a spillover from a much larger event: a general warming in the eastern tropical Pacific during certain years.

This warming results from a weakening of the trade winds and a movement of water from the west-equatorial warm pool (which has been piled up by the trades) toward the east (See also the glossary for "El Ni&#241o" and " Warm pool "). A summary of the cost estimates in US Dollars for the 1982-1983 El Ni&#241o, which was the strongest such event recorded over the past 50 years. Although El Ni&#241o events vary in intensity, the costs from even the smallest event can be staggering. (From: NASA ) El Ni&#241o and its Devastating Effects An El Ni&#241o situation occurs every three or four years or so, mainly in December, and is devastating to the fishing economies of Ecuador and Peru. Birds, sea lions and fishermen go hungry because there are not enough fish to go around. Also, torrential rainfall in the coastal zone frequently accompanies the offshore warming, causing devastating floods (as happened in 1982-1983). See below for a summary of costs associated with the 1982-1983 El Ni&#241o.

El Ni&#241o and California In the North Pacific, the Aleutian low-pressure region (over the Aleutian Islands chain to the southwest of Alaska) and the NE Pacific high-pressure region off California characterize normal conditions. When the trade winds weaken and the eastern Pacific warms up, the Aleutian low-pressure center tends to expand southward. The high-pressure cell off California weakens, and the California Current slows and warms. Fisheries collapse. Kelp forests suffer. Baby sea lions starve. Warm, moist air is widely available, favoring development of storm centers. The jet stream in the upper troposphere and the lower stratosphere , which runs along the boundary of arctic and tropical air, moves farther south. Storm tracks move south along with it, and increasingly impinge on the coast of our region. In summary, extraordinary events of precipitation in our region (which produce high stream flow or flooding) are commonly associated with El Ni&#241o conditions, when the eastern Pacific is unusually warm. Winter storms, generated in the North Pacific, move farther south than at "normal" times. Also, they have the opportunity to pick up moist tropical air along the way.

Absent the offshore high (which acts as a road block), the storm systems can invade our region and dump their load. El Ni&#241o and its effect on the North Pacific, associated with eastern displacement of warm water (red) and associated rain clouds (gray). The warmer equatorial waters heat the atmosphere over time periods measured in months. The atmosphere responds to this heating by producing alternating patterns of low and high pressure, including the low pressure centered just to the southwest of Alaska and another centered over the southeastern United States. (From: NASA ) El Ni&#241o and Climate Change Although El Ni&#241o events are not new (there is evidence they have been occurring for hundreds of years), a distinct change in the behavior of this event beginning in the mid-1970�s has some worried that human-induced climate change may be having its effect.

These recent changes include two �extreme� El Ni&#241o events (the strongest in this century, the 1982 to 1983 event and the longest of this century, the 1990 to 1995 event) and an increased frequency of El Ni&#241o relative to the past 50 years. As is the case with most attempts to pen a modern day observation to global warming , this evidence cannot rule out �natural variation.� Periods of high El Ni&#241o activity have occurred before, as for example from 1880 to 1925. That being said, some computer models of climate change predict precisely what is being observed today: increased likelihood of El Ni&#241o (with one study suggesting an increase of once every five years to once every three years); warming of the tropical Pacific with greater warming in the east than in the west (a pattern generally associated with El Ni&#241o); and a possible increase in El Ni&#241o severity.

In so much as El Ni&#241o is a natural phenomena, it is something we need to live with, just as we do with earthquakes and hurricanes. However, if the current El Ni&#241o trend continues, the consequences could take a heavy toll on the entire world, disrupting everything from the U.S. insurance industry to the prospect for worldwide sustainable development. El Nino Primer El Nino Primer Weather Event Write-Ups El Nino conditions have developed and are very likely (>90% chance) to persist through the 2015-16 winter. The developing El Nino has started to receive attention and so we would like to take a moment to answer some of the common questions that arise when the topic of El Nino comes up... What is El Nino? El Nino is a state where the water temperatures in the Pacific Ocean near the equator become abnormally warm. This is a natural cycle that repeats itself on average about once every 2 to 7 years. El Ninos tend to begin in the summer and usually peak in intensity during the following winter. I don’t live near the equatorial Pacific, why should I care if the ocean is warmer there?

The unusually warm waters in the Pacific Ocean cause a ripple effect in the atmosphere with weather patterns across many areas of the globe altered as the warm waters help shift jet stream patterns. The map below highlights some of the typical impacts from El Nino across the globe. Notice that it often results in droughts in some areas while heavy rain and flooding occur in others. The effects of El Nino in our region tend to be most pronounced during the winter, when moderate to strong El Ninos typically produce warmer than average temperatures and below average precipitation. Has the current El Nino had impacts on the weather patterns yet? The typical warm season El Nino patterns have most definitely already become evident. First, El Nino typically results in a more hostile environment for tropical storms and hurricanes in the tropical Atlantic Ocean and that has certainly been the case this year. There have yet to be any tropical systems in the deep tropical Atlantic and the Caribbean region is experiencing drought conditions. The tropical Pacific on the other hand has been abnormally active, in particular the Central Pacific in and around Hawaii where there have already been 2 tropical storms that have threatened the state, a phenomenon that is quite rare, particularly so early in the season. How is this El Nino comparing to previous El Ninos?

It is important to note that no 2 El Ninos are exactly alike and no 2 El Ninos produce exactly the same impacts on weather patterns. The index that is commonly used to measure the magnitude of the El Nino is already trending toward this El Nino developing into a strong El Nino, similar to the 1982-83 and 1997-98 El Ninos, which both ended up being among the strongest El Ninos observed since 1950. Experts at NOAA’s Climate Prediction Center are now forecasting the current El Nino to be similarly as strong as the 1982-83 and 1997-98 El Ninos. What were the 1982-83 and 1997-98 winters like in this area? Both winters were abnormally warm and featured only about half the average snowfall during the Dec-Feb period. Interestingly, both years saw significant snowstorms during March, which helped push the annual snowfall totals up closer to normal.

Temperatures were above to much above average all 3 winter months during both winters, peaking at +7.1F above average in December 1982 and at 12.4F above average in Feb 1998. If this El Nino is going to be strong like 82-83 and 97-98, then that means this winter will be very warm like those winters, right? The odds certainly favor a warmer than average winter and below average snowfall during the upcoming 2015-16 winter, which is what NOAA’s Climate Prediction Center is currently forecasting. The forecast below was issued on August 20th. It is, however, important to remember that no 2 El Ninos are alike, and even if this year’s El Nino is similar in strength to 82-83 and 97-98, it is not a guarantee that the weather patterns will end up exactly the same. Comparing current Pacific water temperatures to water temperature to those from 1982 and 1997 shows similarities, but one striking difference is the incredibly warm waters farther north in the eastern Pacific.

That abnormally warm water actually extends all the way north off the U.S. west coast up into the Gulf of Alaska. It is unclear if this anomaly will persist through the upcoming winter, and if it does, how and if it will alter the weather patterns from those of a typical moderate to strong El Nino. It has been theorized that these abnormally warm water temperatures, which were present the past couple winters, were a contributing factor to the recent abnormally cold winters. How is a winter officially classified as abnormally cold, warm or normal? The high and low temperatures for each day during the winter are added together and divided by the number of days to determine the average temperature for the winter. This average temperature for the winter is then compared against the 30 year normal average temperature for the winter to determine how close they are. It is important to know that even abnormally warm winters can and often do experience spells of cold and snowy weather, just like abnormally cold winters typically experience thaws. When was the last El Nino? The last El Nino was back in 2009-10 and was a moderate El Nino.

That winter actually ended near to slightly cooler than average as other atmospheric circulations mitigated the effects of the El Nino some. This is reminder that no 2 El Ninos are the same and there are other factors that could play a role in our winter weather and result in the 2015-16 winter not being as anomalously warm as previous strong El Ninos. Additional resources and information on El Nino can be found here: What are El Niño and La Niña? Home Ocean Facts What are El Niño and La Niña? What are El Niño and La Niña? El Niño and La Niña are complex weather patterns resulting from variations in ocean temperatures in the Equatorial Pacific. To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video Warmer or colder than average ocean temperatures in one part of the world can influence weather around the globe. Watch this Ocean Today video to see how this works. El Niño and La Niña are opposite phases of what is known as the El Niño-Southern Oscillation (ENSO) cycle.

The ENSO cycle is a scientific term that describes the fluctuations in temperature between the ocean and atmosphere in the east-central Equatorial Pacific (approximately between the International Date Line and 120 degrees West). La Niña is sometimes referred to as the cold phase of ENSO and El Niño as the warm phase of ENSO. These deviations from normal surface temperatures can have large-scale impacts not only on ocean processes, but also on global weather and climate . El Niño and La Niña episodes typically last nine to 12 months, but some prolonged events may last for years. While their frequency can be quite irregular, El Niño and La Niña events occur on average every two to seven years. Typically, El Niño occurs more frequently than La Niña. El Niño El Niño means The Little Boy, or Christ Child in Spanish. El Niño was originally recognized by fishermen off the coast of South America in the 1600s, with the appearance of unusually warm water in the Pacific Ocean. The name was chosen based on the time of year (around December) during which these warm waters events tended to occur.

The term El Niño refers to the large-scale ocean-atmosphere climate interaction linked to a periodic warming in sea surface temperatures across the central and east-central Equatorial Pacific. Typical El Niño effects are likely to develop over North America during the upcoming winter season. Those include warmer-than-average temperatures over western and central Canada, and over the western and northern United States. Wetter-than-average conditions are likely over portions of the U.S. Gulf Coast and Florida, while drier-than-average conditions can be expected in the Ohio Valley and the Pacific Northwest. The presence of El Niño can significantly influence weather patterns, ocean conditions, and marine fisheries across large portions of the globe for an extended period of time. La Niña La Niña means The Little Girl in Spanish. La Niña is also sometimes called El Viejo, anti-El Niño, or simply "a cold event." La Niña episodes represent periods of below-average sea surface temperatures across the east-central Equatorial Pacific. Global climate La Niña impacts tend to be opposite those of El Niño impacts. In the tropics, ocean temperature variations in La Niña also tend to be opposite those of El Niño.

During a La Niña year, winter temperatures are warmer than normal in the Southeast and cooler than normal in the Northwest. Search Our Facts NOAA's National Ocean Service: Education: Professional Development: Oceans, Weather, and Climate product_detail.aspx? id=10.2505/7/SCB-CRE.1.1 This tutorial explores global weather and climate patterns, focusing on why different conditions exist in specific areas. The Earth’s weather patterns, which consist of different conditions of temperature, precipitation, humidity, wind, air pressure, etc., result in various climate zones across the globe. Weather and climate are the result of the transfer of energy from the sun at and near the surface of the Earth. Solar radiation heats land masses, the ocean, and air differently, resulting in the constant transfer of energy across the globe. Transfer of thermal energy at the boundaries between the atmosphere, land masses, and the ocean are influenced by dynamic processes such as cloud cover, and relatively static conditions such as the position of mountain ranges and the ocean. This transfer of thermal energy results in layers of different temperatures and densities in both the ocean and atmosphere. The action of gravitational force on regions of different density causes these layers to rise or fall, forming convection currents (cells).

This circulation, influenced by the rotation of the Earth, produces winds and ocean currents. Learning Outcomes: Explain why the temperature of the ocean does not generally fluctuate as dramatically as the temperature of the land. Describe the relationship between density of liquids and gases and their temperatures. Describe the evolution of a typical reef system. Explain how a difference in density of different layers/portions of a fluid will cause internal currents (rising and falling of the fluid). Explain the cause of predictable wind patterns along the coastal regions of large land masses. Describe how the Coriolis effect determines the direction of the movement of air and water currents. List the major variables that affect the transfer of energy through the atmosphere. Provide an example showing how the transfer of energy affects weather and climate. Explain how convection relates to weather, including its role in the development of circulation patterns. Global Precipitation and Energy product_detail.aspx? id=10.2505/7/SCB-CRE.1.1 This tutorial explores the distribution of water and energy on Earth. The cycling of water in and out of the atmosphere and ocean affects the Earth’s climates by influencing patterns of precipitation and by transferring energy between the ocean and the atmosphere.

As water moves through the water cycle, it evaporates from the Earth’s surface, rises and cools, condenses into rain, snow, or ice, and falls back to the surface. The water falling on land collects in rivers and lakes, soil, and porous layers of rock, and much of it eventually flows back into the ocean. The water cycle connects the ocean to all of the Earth’s water reservoirs by evaporation and precipitation. The ocean loses thermal energy due to the evaporation of water. This energy transfer drives atmospheric circulation as water moves to the atmosphere as vapor and eventually condenses, releasing thermal energy to the surrounding air. Learning Outcomes: Outline the basic steps in the water cycle in terms of density, energy of the water, and the relative molecular arrangement and motion in each phase. Describe how energy is transferred to the atmosphere by heating from the ocean and by the evaporation of water and its subsequent condensation. Identify the sun as the energy source that drives atmospheric circulation and the movement of masses of air and water from one place on Earth to another (through convection). List sources for the water cycle and identify the largest source.

Explain the relationship between water, temperature, the amount of water evaporated into the atmosphere (and subsequently condensed), and the energy of the atmosphere at or near the location of evaporation. Global Circulation Patterns product_detail.aspx? id=10.2505/7/SCB-CRE.1.1 This tutorial explores ocean circulation patterns and the effect that the ocean has on climate. Water in the ocean holds a lot of thermal energy (more than an equal amount of land). Throughout the ocean there is a global circulation system that transfers this thermal energy across the Earth. The shape of the ocean basins and adjacent land masses influence the path of circulation. As ocean currents transfer thermal energy to various locations, the temperature of the atmosphere above the ocean is affected. For example, the condensation of water that has been evaporated from warm seas provides the energy for hurricanes and cyclones. When the pattern of thermal energy released into the atmosphere changes, global weather patterns are affected. An example of a large-scale impact such as this is the El Niño Southern Oscillation, which changes the pattern of thermal energy released into the atmosphere in the Pacific.

Learning Outcomes: Explain how the ocean might influence and affect local weather and climate, given a specific location (on the planet near the ocean) and the local ocean currents. Describe the cause of hurricanes and explain why they usually occur within specific regions during certain times of the year. Explain how changes in ocean temperatures (over a period of months) affect factors that influence weather patterns. List the major variables that affect the transfer of energy through the ocean. Changing Climate El Niño: a warm current of water El Niño a warm current of water El Niño (Spanish name for the male child), initially referred to a weak, warm current appearing annually around Christmas time along the coast of Ecuador and Peru and lasting only a few weeks to a month or more. Every three to seven years, an El Niño event may last for many months, having significant economic and atmospheric consequences worldwide. During the past forty years, ten of these major El Niño events have been recorded, the worst of which occurred in 1997-1998 . Previous to this, the El Niño event in 1982-1983 was the strongest. Some of the El Niño events have persisted more than one year.

El Niño Years Selected text from: CPC ENSO Main Page In the tropical Pacific, trade winds generally drive the surface waters westward. The surface water becomes progressively warmer going westward because of its longer exposure to solar heating. El Niño is observed when the easterly trade winds weaken, allowing warmer waters of the western Pacific to migrate eastward and eventually reach the South American Coast (shown in orange). The cool nutrient-rich sea water normally found along the coast of Peru is replaced by warmer water depleted of nutrients, resulting in a dramatic reduction in marine fish and plant life . Animation by: Shao In contrast to El Niño, La Niña (female child) refers to an anomaly of unusually cold sea surface temperatures found in the eastern tropical Pacific. La Niña occurs roughly half as often as El Niño. La Niña Years How Does El Niño Shape Weather Across the Globe? How Does El Niño Shape Weather Across the Globe? By By Mark Leberfinger, AccuWeather.com Staff Writer August 10, 2014, 1:58:13 AM EDT One of the bigger players in shaping the world’s weather is a force called El Niño.

It is a phase of the El Niño Southern Oscillation, or ENSO, in which water temperatures of the central and equatorial Pacific Ocean are above normal. Computer models predict ocean currents, which allow warm water to pool in certain areas of the ocean. “When this pooling of warm water extends along the equator from the South America coast on west through the international date line for more than three consecutive months, we have an El Niño,” AccuWeather Senior Meteorologist Dale Mohler said. The opposite effect of cooler water over a similar time period is known as La Niña. While the latest rendition of El Niño has not officially started, some impacts have been noted globally. “Most notable is the drought in Malaysia and the struggling monsoon in India,” AccuWeather Senior Meteorologist Jason Nicholls said. Some of the other potential impacts from El Niño include wetter-than-normal weather along the United States Gulf Coast, mainly in the late fall and winter, and a reduced hurricane season in the Atlantic. “Western Canada tends to have mild winters during an El Niño. Central America is dry and warm in the summer months. Drought intensifies over Indonesia and northeast Australia. Eastern South Africa tends to be dry and warm,” Mohler said.

"No El Niño is created equal. The stronger the El Niño is the greater the impact," he said. "Strong El Niños also tend to last longer, sometimes as long as two years. Timing of where the impact begins seems to be random from year to year.” RELATED: Long-Range Forecasting Takes More Than a Crystal Ball El Niño is not expected to develop until the fall so there may not be many true impacts until late-summer or fall in the U.S. “The southern tier of the U.S. is probably this most likely area to feel the impacts first," Nicholls said. "This year's El Niño looks to be weak to at best, moderate, so we may not see textbook El Niño said effects in the U.S. In fact, the [AccuWeather] Long-Range Team feels other factors than El Niño may play a bigger part in the pattern this fall and winter." Several global agencies monitor the oceans along with NOAA, including Australia's Bureau of Meteorology, Japanese Meteorological Agency and several others, issuing summaries on the progress of ENSO on a monthly or bi-monthly basis, Nicholls said.

“Knowing the state of the Pacific Ocean and the forecast of El Niño can help countries prepare for possible negative impacts from El Niño/La Niña such as droughts or flooding,” he said. The information is also used by farming and other industries. “Commodities such as grains should be conserved where drought is expected in the coming year,” Mohler said. “The southern Plains typically have wet falls and winters during an El Niño, so I would expect increased wheat acreage planted this fall over Texas and Oklahoma. Chain stores such as Lowes and Home Depot will stock less generators and plywood in their East Coast and Gulf Coast stores as the hurricane risk this fall is less.” > More Weather News It will feel like the single digits in Pittsburgh, Green Bay for NFL Wild Card Weekend Weather News - January 05, 2017, 1:17:20 PM EST Fans across the country headed to the NFL Wild Card Weekend playoff games will endure brutal cold and occasionally wet or snowy weather.

Travel may grind to halt in Istanbul as snow, arctic air target Turkey into this weekend Weather News - January 05, 2017, 11:55:40 AM EST Disruptive snow and plunging temperatures will sweep across western and central Turkey, including Istanbul, from Friday through this weekend. UK mild weekend to be dampened by cloud and showers Weather News - January 05, 2017, 11:42:45 AM EST The frosty start to the week will be replaced by a milder spell across the United Kingdom this weekend, but cloud and odd showers will remain. Snowy, icy roads to create treacherous travel scenario for DC to Boston Weather News - January 05, 2017, 9:49:37 AM EST A blast of chilly air will set the groundwork for quick-hitting snow and a freeze-up along the northeastern United States Interstate 95 corridor late this week.

Snow, freeze-up threaten to immobilize southern US this weekend Weather News - January 05, 2017, 8:59:43 AM EST A winter storm will unload snow ahead of a freeze-up that will threaten to immobilize part of the southern United States this weekend. Germany: Late-week cold snap to be harshest since 2012 across south Weather News - January 05, 2017, 7:42:20 AM EST Bitter cold will continue to grip Germany through at least Friday, producing the lowest temperature readings since 2012 across the south. Weather News - January 05, 2017, 5:36:49 AM EST Snow will threaten to cause slick travel across parts of the southwestern United States into Friday. Excessive rain, melting snow may cause worst California flooding since 1997 Weather News - January 04, 2017, 10:52:34 AM EST A large storm will affect the west coast of the United States with drenching rain, flooding and high country snow this weekend into next week.

El Nino & La Nina Information El Nino & La Nina Information Current Conditions Weak La Niña conditions are currently present. A weak La Niña is favored to persist (~75% chance) through December 2016, and slightly favored to persist (~55% chance) December 2016 through February 2017. Consequently, a La Niña advisory is now in effect for the fall-winter of 2016-17. Tropical Pacific Sea Surface Temperatures Tropical Pacific Sea Surface Temperature Anomalies Tropical Pacific sea surface temperatures (left image) and associated anomalies (right image). Click images to enlarge. Images courtesy of the Climate Prediction Center. What is El Niño-Southern Oscillation (ENSO)? Note: Most of the information in this article is courtesy of climate.gov. The El Niño-Southern Oscillation (ENSO) is a recurring climate pattern involving changes in the temperature of waters in the central and eastern tropical Pacific Ocean. On periods ranging from about three to seven years, the surface waters across a large swath of the tropical Pacific Ocean warm or cool by anywhere from 1°C to 3°C, compared to normal.

This oscillating warming and cooling pattern, referred to as the ENSO cycle, directly affects rainfall distribution in the tropics and can have a strong influence on weather across the United States and other parts of the world. El Niño and La Niña are the extreme phases of the ENSO cycle; between these two phases is a third phase called ENSO-neutral. El Niño: A warming of the ocean surface, or above-average sea surface temperatures (SST), in the central and eastern tropical Pacific Ocean. Over Indonesia, rainfall tends to become reduced while rainfall increases over the central and eastern tropical Pacific Ocean. The low-level surface winds, which normally blow from east to west along the equator (“easterly winds”), instead weaken or, in some cases, start blowing the other direction (from west to east or “westerly winds”). In general, the warmer the ocean temperature anomalies, the stronger the El Niño (and vice-versa). La Niña: A cooling of the ocean surface, or below-average sea surface temperatures (SST), in the central and eastern tropical Pacific Ocean. Over Indonesia, rainfall tends to increase while rainfall decreases over the central and eastern tropical Pacific Ocean.

The normal easterly winds along the equator become even stronger. In general, the cooler the ocean temperature anomalies, the stronger the La Niña (and vice-versa). Neutral: Neither El Niño or La Niña. Often tropical Pacific SSTs are generally close to average. However, there are some instances when the ocean can look like it is in an El Niño or La Niña state, but the atmosphere is not playing along (or vice versa). Maps of sea surface temperature anomaly in the Pacific Ocean during a strong La Niña (top, December 1988) and a strong El Niño (bottom, December 1997). Maps by NOAA Climate.gov, based on data provided by NOAA View. ENSO is one of the most important climate phenomena on Earth due to its ability to change the global atmospheric circulation, which in turn, influences temperature and precipitation across the globe. We also focus on ENSO because we can often predict its arrival many seasons in advance of its strongest impacts on weather and climate. So, by now, you might have noticed that while “ENSO” is a nice catchall acronym for all three states, that acronym doesn’t actually have the word La Niña in it.

Why is that? Well, that is a fluke of history. Before La Niña was even recognized, South American fisherman noticed the warm up of coastal waters occurred every so often around Christmas. They referred to the warming as “El Niño,” (niño being Spanish for a boy child) in connection with the Christmas holiday. Sir Gilbert Walker discovered the “Southern Oscillation,” or large-scale changes in sea level pressure across Indonesia and the tropical Pacific. However, he did not recognize that it was linked to changes in the Pacific Ocean or El Niño. It wasn’t until the late 1960s that Jacob Bjerknes and others realized that the changes in the ocean and the atmosphere were connected and the hybrid term “ENSO” was born. It wasn’t until the 1980s or later that the terms La Niña and Neutral gained prominence. Typical winter impacts associated with ENSO neutral events. Colder probabilities are favored across north-central and northeast portions of the US, due to a polar jet stream shifted further south. Meanwhile, warmer probabilities are favored across ths southern US, with above normal precipitation favored across portions of the southeast US. Image courtesy of Ray Wolf, National Weather Serivce.

Typical late fall through early spring upper level jet stream positions associated with moderate to strong La Niña (left) and El Niño (right) events. During La Niña, a variable Pacific jet stream in association with a polar jet stream shifted further south favors below normal precipitation across the southern US, with below normal temperatures across the northern US. During El Niño, a strong and amplified Pacific jet stream extending across the southern US in association with a polar jet stream shifted further north into Canada favors above normal precipitation across the southern US, and above normal temperatures over the northern US. Based on original graphics from NOAA’s Climate Prediction Center. El Niño Temperature/Precipitation Anomalies Below are winter (November-March) and summer (May-September) temperature and precipitation anomalies for El Niño episodes since 1950. The anomalies are based 1971-2000 and 1981-2010 normals. These composites are not intended to be a forecast of expected conditions. Rather, they use historical data to highlight locations where ENSO can potentially impact temperature and precipitation. Other climate and weather processes along with atmospheric variability may make the impacts of one ENSO event different than another.

Some events may be associated with very extreme climate conditions which may dominate the composites. The below composites suggest slightly warmer than normal temperatures are favored across northeast Kansas during winter, with near normal temperature elsewhere. Slightly cooler than normal temperatures are favored over northwest Kansas during summer, with near normal temperatures elsewhere. Meanwhile, near to slightly above normal precipitation is favored across much of the state during winter and over northwest Kansas during summer, with near normal precipitation elsewhere. Winter (Nov-Mar) Temperature Summer (May-Sept) Precipitation La Niña Temperature/Precipitation Anomalies Below are winter (November-March) and summer (May-September) temperature and precipitation anomalies for La Niña episodes since 1950. The anomalies are based 1971-2000 normals. These composites are not intended to be a forecast of expected conditions. Rather, they use historical data to highlight locations where ENSO can potentially impact temperature and precipitation. Other climate and weather processes along with atmospheric variability may make the impacts of one ENSO event different than another. Some events may be associated with very extreme climate conditions which may dominate the composites.

The below composites suggest near to above normal temperatures are favored across Kansas during winter and summer months. Meanwhile, below normal precipitation is favored across much of the state during the winter and summer months. Winter (Nov-Mar) Temperature October - December November - January The above images depict chances of extreme wet or dry three-month periods associated with past La Niña's since 1950. Warm colors indicate an increased risk of dry precipitation extremes, while green colors indicate an increased risk of wet precipitation extremes. Other than a few exceptions, there is generally an increased risk of dry precipitation extremes across Kansas throughout the year. Click each image to enlarge. Images courtesy of NOAA's Earth System Research Laboratory. Agricultural Impacts The following images show historical ENSO impacts on corn yield across the Heartland. Unfortunately, impacts are unavailable for crops other than corn at this time. These composites are not intended to be a forecast of expected yields. Rather, they use historical data (1981-2010) to highlight locations where ENSO can potentially impact climate conditions and associated corn yields to help you make more informed farm management decisions. Images courtesy of Useful to Useable (U2U).

El Niño Corn Yield Departure from Normal Historical corn yields (left) and corn yield departure from normal (right) for El Niño years since 1981. Green colors on the "departure from normal" image depict above normal yields, while brown colors indicate below normal yields. Click images to enlarge. Images courtesy of Useful to Useable (U2U). La Niña Corn Yield Departure from Normal Historical corn yields (left) and corn yield departure from normal (right) for La Niña years since 1981. Green colors on the "departure from normal" image depict above normal yields, while brown colors indicate below normal yields. Click images to enlarge. Images courtesy of Useful to Useable (U2U). Neutral Corn Yield Departure from Normal Historical corn yields (left) and corn yield departure from normal (right) for ENSO neutral years since 1981. Green colors on the "departure from normal" image depict above normal yields, while brown colors indicate below normal yields. Click images to enlarge. Images courtesy of Useful to Useable (U2U). Official Long-Range Forecasts The below long-range outlooks are courtesy of the Climate Prediction Center (CPC).

They indicate probabilities of above, near or below normal temperature/precipitation for the given time period. They do NOT represent the expected magnitude of warm/cool and/or wet/dry weather. Professionals at CPC take into account many different factors when assembling these forecasts, including the ENSO composites posted throughout this report. Click images to enlarge. One-Month Forecast Above/Below Normal Precipitation Probabilities ENSO & Spring Severe Thunderstorm Frequency A paper published in Nature Geoscience in April 2015 by John Allen, Michael Tippett, and Adam Sobel examines the influence of El Niño/La Niña on springtime hailstorms and tornadoes across the contiguous United States from late winter through spring. The below images are adapted from the paper, and show tornado and hail frequencies for the spring months (March-May) during El Niño (left column) and La Niña (right column). The authors explain that the connection between El Niño/La Niña conditions and summertime storms is less clear, and unfortunately that is the time of year when severe storms peak throughout much of the United States.

But for springtime, at least, El Niño/La Niña data may be able to refine seasonal severe weather outlooks. These composites are not intended to be a forecast of expected conditions. Rather, they use historical data to highlight locations where ENSO can potentially impact spring severe weather. Tornado and hail frequencies for the spring months (March-May) during El Niño (left column) and La Niña (right column). Purple favors higher storm event frequency, and brown favors lower storm event frequency. Specifics vary, but in general, springtime tornadoes and hailstorms are less frequent in the central and southern United States during El Niño, and more frequent during La Niña. Image courtesy of NOAA climate.gov. Additional Links/Resources El Niño, explained: A guide to the biggest weather story of 2015 - Vox El Niño, explained: A guide to the biggest weather story of 2015 share Over the past year, scientists have been keeping a close eye on an important swath of the Pacific Ocean, just along the equator. When conditions here get just right, an El Niño can form — wreaking havoc on weather patterns across the globe.

The El Niño currently brewing in the Pacific is shaping up to be one of the strongest ever recorded . This phenomenon is expected to peak before January, with far-reaching impacts all winter and spring. Based on past experience, El Niño could potentially bring much-needed rain to California, but also drought in Australia, destructive floods in Peru, and so on. El Niño has already helped make 2015 the hottest year on record — and might well do the same for 2016. That said, El Niño events are often unpredictable and full of surprises. So what follows is a guide to how El Niño works, what we know about the 2015 event, and how a potentially massive El Niño could upend the world's weather over the coming months. A very basic definition of El Niño El Niño is a weather phenomenon that occurs irregularly in the eastern tropical Pacific every two to seven years. When the trade winds that usually blow from east to west weaken, sea surface temperatures start rising, setting off a chain of atmospheric impacts. El Niños can be strong or weak.

Strong events can temporarily disrupt weather patterns around the world, typically making certain regions wetter (Peru or California, say) and others drier (Southeast Asia). Some countries suffer major damage as a result. El Niños also transfer heat stored in the deeper layers of the ocean to the surface. When combined with global warming, that can lead to record hot years, as in 1998. "El Niño" got its name in the 1800s from Peruvian fisherman, who first noticed a mysterious warm current that would appear around Christmas. They called it the "little boy" or "Christ child." Why this year's El Niño is a huge deal The last truly massive El Niño appeared in 1997-'98 and ended up causing an estimated $35 billion in destruction and 23,000 deaths around the world. (It also inspired that famous Chris Farley sketch .) Now we're facing a similarly massive event: Late-October status of the 1997 and 2015 El NIño events in terms of satellite-derived data showing departure from average sea surface height for a given time of year, which is correlated with warmth in the upper ocean.

( NASA/JPL ) That, in itself, is a surprise. Back in March, NOAA's Climate Prediction Center announced that a weak El Niño had formed in the Pacific, but many experts initially thought it might fizzle out by summer. Instead, this El Niño kept strengthening, with ocean temperatures in the eastern tropical Pacific continuing to soar. By mid-November, temperatures in one critical part of the ocean, the Niño 3.4 region, were running even hotter than they were in 1997: ( Jan Null ) "Right now we say we think it's really going to be one of the three strongest ones," said Michel Jarraud, the secretary general of the World Meteorological Organization, who compared it with the 1997-98, 1982-83, and 1972-73 El Niño events. "It may be one of the two; that we don't know yet. But definitely it's already a very strong one." Countries across the globe will have to brace themselves as this event peaks this winter and lasts through the spring.

El Niño has already triggered longer droughts in Indonesia, enabling massive man-made peatland fires to rage out of control, creating toxic haze that has spread as far as Singapore. Warmer ocean temperatures have also caused a major coral bleaching event , harming reefs around the world. And El Niño may just be getting started: In the past, major events have brought unusually hot, dry weather to Australia that can cramp wheat yields and amp up wildfires. It can bring hotter, drier weather to India that hurts agriculture. It can bring heavy rain and destructive flooding to Peru, washing away houses and spreading cholera. That said, El Niño isn't all bad. In the United States, it could bring some needed rain this winter to ease California's drought (though also deadly mudslides and flooding). Historically, El Niño has also served up milder US winters and tamped down on Atlantic hurricanes. One important caveat, however, is that every El Niño unfolds a bit differently — and some have unexpected impacts.

As NOAA's Emily Becker points out , strong El Niño events usually bring rain to California in the winter (as in 1982-'83), but occasionally they don't (as in 1965-'66): ( NOAA Climate Prediction Center ) Another key story to watch is how a strong El Niño might push up temperatures worldwide. Global average temperatures are already going up over time, thanks to all the carbon dioxide we're adding to the atmosphere. According to NASA, 2014 was the hottest year on record. But there was no El Niño that year — and El Niño years tend to be a bit hotter than average , as heat gets transferred from the ocean to the surface. The combination of El Niño and rising CO2 is already helping 2015 shatter heat records . The big question now is whether it'll do the same for 2016: (NOAA) Bottom line: There are still a lot of question marks about how this will unfold. But El Niño could well be the biggest weather story of the next several months, with ripple effects around the globe.

How El Niño actually works, step by step To see how El Niño works, it helps to understand what the equatorial Pacific looks like under normal, or "neutral," conditions: 1) Neutral conditions in the equatorial Pacific Ocean Normally, the tropical Pacific features strong trade winds that blow warm ocean water from east to west, where it piles up near Indonesia. Meanwhile, back east along South America, frigid water deep down in the ocean gets pulled up closer to the surface, cooling the area around Peru. Here's a diagram: (William Kessler/NOAA/PMEL) As a result, during "neutral" conditions, sea levels are about half a meter higher near Indonesia than they are in Peru. And the surface water near Indonesia is about 8°C warmer (14.4°F) than it is near Peru. That temperature difference creates a convective loop in the atmosphere that, in turn, reinforces the trade winds. This ends up affecting a lot more than just this stretch of ocean. Because the Pacific is so vast, this system is a major driving force in the global climate. The large, warm pool of water near Indonesia causes the air above it to rise, creating rainfall in the region.

And this system shapes the jet streams that guide weather and storms around the world. That's how it works under normal conditions, anyway. But things look a little different when El Niño comes along. 2) Now along comes El Niño Every few years, those prevailing Pacific trade winds that blow east to west can weaken. (Scientists are still debating the nuances of exactly why this happens.) When the trade winds weaken, all that warm water that was piled up near Indonesia starts sloshing back eastward, pulled back down by gravity. What's more, the underwater layer known as the thermocline starts sinking. As a result, there's less cold water rising up from the deep ocean near South America — so the waters near Peru start warming up. Here's another diagram: (William Kessler/NOAA/PMEL) This causes sea surface temperatures in the east and central Pacific to start rising and the trade winds to weaken even further. What's more, rainfall starts following that warm pool of water as it travels eastward. That's why El Niño is usually associated with drier weather in places like Indonesia and Australia, as well as heavier rains in places like Peru (or California). The rain is essentially moving east.

Scientists officially declare an El Niño when sea surface temperatures in the equatorial Pacific Ocean (known as the Niño 3.4 region ) rise 0.5°C above their historical baseline for three months in a row — and once atmospheric conditions and rainfall patterns shift accordingly. Again, because the Pacific is so vast, an El Niño can have large ripple effects on weather around the world, especially during the winter months. Here's a look at the changes that have historically accompanied El Niño events: Typical effects of an El Niño during the winter: (NOAA) A strong El Niño can weaken monsoons in the Indian Ocean, for example. It can also cause the jet stream to start stretching from the Eastern Pacific across the southern United States, bringing rainfall and storms with it. Still, a lot depends on how strong the El Niño actually is — and occasionally there are aberrations and exceptions to the rule. More on that below. El Niño's return in 2015 — and why scientists have been talking about a "Godzilla" event Ever since early 2014, scientists have been expecting this latest El Niño to form.

But, in a sign of how slippery the system can be, El Niño kept defying predictions and not showing up. Finally, in March 2015, after several false starts, scientists at NOAA's climate prediction center were ready to declare that a weak El Niño was underway. Specifically, sea surface temperatures in that Niño 3.4 region (roughly in the center of the chart below) had been at least 0.5°C above their baseline since September. And, importantly, atmospheric conditions were responding in turn, with more rain over the central Pacific and less rain over Indonesia: Sea surface temperature departures from average (based on 1981–2010) at the end of February 2015. NOAA map by Emily Becker, Climate Prediction Center. At the time, however, NOAA's forecasters said that this El Niño looked "weak," with possibly minimal effects on global weather patterns, and only had a 50 to 60 percent chance of lasting through the summer. Then, somewhat unexpectedly, El Niño kept getting stronger and stronger. And stronger.

By October 2015, sea surface temperatures had soared to more than 2°C above baseline in the Niño 3.4 region, and scientists were seeing strong telltale atmospheric changes. Notice how the anomalous warm area has moved east and is much, much warmer than usual: Average sea surface temperature departure from the 1981-2010 average over the four weeks ending on November 7. Graphic by climate.gov, data from NCEP-NCAR reanalysis. ( Forecasters now expect this El Niño to peak between October and January, and when it does, it's likely to rank among the two or three strongest ever record (along with 1997-'98, 1982-'83, and 1972-'73.) Some forecasters have even dubbed this one a potential "Godzilla." We're already started to see some major El Niño impacts around the world. A paucity of rainfall in Indonesia this fall allowed manmade forest and peat fires to rage out of control , choking the region in a thick toxic haze. And the warmer Pacific waters have fostered an unusually active tropical cyclone season, a hallmark of El Niño.

On the flip side, however, the event has also fostered more wind shear in the Atlantic that has curtailed hurricane activity there. El Niño could bring rain to California — but may not end the drought As noted above, El Niño tends to be associated with changes in weather patterns around the world, especially during the Northern Hemisphere winter. One tantalizing possibility is that a strong El Niño will bring more rain to California, alleviating the state's drought. But even here, nothing is certain. El Niño only affects US weather indirectly, by altering atmospheric circulation and shifting the North Pacific jet stream. (See here for a lucid explanation by Columbia University's Anthony Barnston.) This is an intricate chain of events, and small kinks at certain points can affect the ultimate outcome. As such, Becker cautions people to think not in terms of certainties but in terms of probabilities. Here's an example of how El Niño might shift the odds of a wetter-than-average winter for California (she notes that this isn't a prediction, just an illustration): An example of how a strong El Niño could shift the odds for the amount of seasonal precipitation. Official outlooks from the Climate Prediction Center are available here .

In other words, thanks to El Niño, California has a greater chance of a wetter winter, but not a 100 percent chance. What's more, even if rain does come, that may not be enough to completely erase the massive water deficit that California has built up over the past five years. The state likely needs record precipitation to end the drought, and it also needs the right mix of rain (to recharge the reservoirs) and snow in the Sierra Nevada mountains (to melt during the spring and summer). Also, be warned: Heavy rain after a drought can bring floods and mudslides. Southern California got a possible preview in mid-October, when a short burst of intense rains led to major mudflows that trapped hundreds of cars. So people need to be ready. El Niño tends to hurt some countries and benefit others It's not quite right to say that El Niño events are "bad" or "good." They tend to have different impacts on different regions. One recent study from the University of Cambridge found that on average, El Niño events hurt economic activity in Australia, Chile, Indonesia, India, Japan, New Zealand, and South Africa.

The reasons varied: drought and reduced crop yields in Australia and India, forest fires in Indonesia, less productive fisheries in Peru. But that study also found that on average, El Niño tended to boost the economies in Argentina, Canada, Mexico, and even the United States, at least in the very short term. Again, many factors were at play: In addition to bringing needed rain to California and Texas, El Niño was associated with less tornado activity in the midwestern United States and fewer hurricanes in the Atlantic Ocean. Here's a table of the estimated economic impacts on a broad selection of countries: ( Cashin et al, 2014 ) Again, every big El Niño is different and has its own idiosyncrasies. So think of this table as more a rough guide than gospel. There are also two important twists here. As the WMO's Michel Jarraud stressed in his October news conference, many countries have learned from the past and implemented measures to guard against El Niño's impacts.

(Mexico, for instance, was well-prepared for a record-strength Pacific hurricane that hit the state last month.) Conversely, this El Niño is also playing out in the context of record warm ocean temperatures, so it could have unpredictable impacts. "Our scientific understanding of El Niño has increased greatly in recent years. However, this event is playing out in uncharted territory," said Jarraud. "This naturally occurring El Niño event and human induced climate change may interact and modify each other in ways which we have never before experienced." El Niño is helping make 2015 a record hot year. What about 2016? Thanks to global warming , the Earth's average surface temperature has been going up over time. But there's a lot of variation from year to year. El Niño years tend to be a bit hotter than average. La Niña years (when those trade winds strengthen rather than weaken) tend to be a bit cooler than average. Like so: ( NASA ) What's going on here? As humans load more greenhouse gases into the atmosphere, we're trapping more and more heat on the Earth's surface. But more than 90 percent of that extra heat is absorbed by the oceans.

So subtle interactions between the ocean and the atmosphere can make a big difference for surface temperatures. When conditions in the Pacific are neutral, more of that heat is trapped beneath the ocean surface. When a strong El Niño forms, more of that heat is transferred to the surface. That's why the Earth's average surface temperatures reached new highs in 1998: You had the combination of global warming and an extremely strong El Niño. What was remarkable about 2014 is that it was likely the hottest year on record even without an El Niño event — a sign that Earth keeps getting warmer overall. Meanwhile, 2015 is basically guaranteed to be even hotter than 2014. Now throw a monster El Niño into the mix, and we're looking at a potential shattering of records. Back in January, NASA's Gavin Schmidt explained at a press conference that temperatures typically peak about three months after an El Niño event. Given that forecasters expect this current El Niño to last until next spring, it's entirely possible we could see 2016 also set new highs. We'll have to wait and see.

Further reading: NOAA's ENSO blog is a terrific source of information for updates on El Niño. Weather Underground also posts frequent insightful updates. It's also worth reading this piece by Eric Guilyardi, of the University of Reading, on the challenges that forecasters have in modeling ENSO, the Pacific Ocean system of which El Niño is a part. "Until we understand more, we may have to come to terms that, for the foreseeable future, ENSO may not be reliably predicted more than a few months in advance," he writes.

Question: Where is El Nino, a warm current that affects the world's weather?
Answer: Pacific