What is El Niño?
By Shaun Tanner
Infographic by Jerimiah Brown
The National Oceanic and Atmospheric Administration (NOAA) has warned that the ongoing El Niño episode could rival the strongest El Niños on record (1982-83, 1997-98) and is nearly certain to last into the Northern Hemisphere spring of 2016.
Bill Patzert, a climatologist with NASA’s Jet Propulsion Laboratory, gave this El Niño its “Godzilla” moniker. The “Godzilla” El Niño of 2015-2016 is expected to be one of the strongest on record, having large consequences on global weather. But not all of El Niño’s impacts are monstrous, and some can even be positive. Knowing what to expect can help people deal with the worst effects of El Niño.
Latest forecast
By Bob Henson
Strong El Niño conditions remain in place. The weekly sea surface temperature reading, taken within the Niño 3.4 region near the equator, currently sits at 2.4°C above average. NOAA provides an update on El Niño conditions each Monday.
Monthly Outlook (October 8, 2015):
More background:
Unusually warm waters now extend from the South American coast westward to the International Date Line in a classic El Niño signature. For much of 2014, the atmosphere failed to respond to several brief warmings of the eastern tropical Pacific, but now both ocean and air are locked into the synchrony that builds and sustains the strongest El Niño events.
The only El Niño events in NOAA’s 1950-2015 database comparable in strength to the one now developing occurred in 1982-83 and 1997-98. A single pair of cases is a thin framework on which to build any projections of what El Niño may bring across North America this winter. However, three other episodes since 1950 are rated as “strong” (Niño 3.4 readings topping the SST threshold of +1.5°C for at least three overlapping three-month periods). Many of the far-flung atmospheric responses to El Niño become more reliable the stronger the event, so it’s wise to look especially closely at these cases, rather than simply averaging across all El Niño events.
Read more about El Niño’s effects on North America by reading Bob Henson’s blog post on the Dr. Jeff Masters’ Blog. Keep reading for localized U.S. and global forecasting.
SST Anomalies
NOAA outlooks
NOAA’s Temperature Probability Outlook spanning October to March. Source: NOAA/National Weather Service
NOAA
is the premier source of weather data and official forecasting for the
U.S. In the Temperature Probability Outlook map below, color codes are
based on the probability that a specific region will be warmer (red) or
colder (blue) than average. Contrary to common misconceptions, higher
percentages do NOT mean higher temperatures. On the red end of the
scale, high percentages simply mean a greater probability for higher
than average temperatures. High percentages on the blue side mean it is
more than likely that region will experience colder than average
temperatures.Similarly, in the Precipitation Probability Outlook map below, colors indicate the probability of a region having more (green) or less (brown) precipitation than average. Dark green areas indicate a higher probability of higher than average precipitation. On the other hand, dark brown areas mark a higher than likely chance there will be less than average precipitation.
Equal chance, marked by white regions and a 50% probability, does not mean “normal.” These regions literally indicate “equal chance” regions, meaning it is equally probable that the season will be average as it is that the season will see abnormal phenomena.
NOAA’s Precipitation Probability Outlook spanning October to March. Source: NOAA/National Weather Service
Weak v. strong episodes
By Madeline Rae
Every month, the Oceanic Niño Index (ONI) finds the running mean of sea surface temperature anomalies for the past three months (i.e. January-February-March, February-March-April, etc.) When there are five consecutive three-month means that are above normal, NOAA declares it an El Niño episode.
Since records began in 1950, there have been 23 years officially classified as El Niño. Each season is further categorized by its strength.
Weak: 0.5-0.9ºC sea surface temperature anomaly; twelve recorded episodes including 1951, 1952, 1953, 1958, 1968, 1969, 1976, 1977, 1979, 1994, 2004 and 2006
Moderate: 1.0-1.4ºC sea surface temperature anomaly; six recorded episodes including 1963, 1986, 1987, 1991, 2002 and 2009
Strong: 1.5-1.9ºC sea surface temperature anomaly; three recorded episodes including 1957, 1965 and 1972
Very Strong: 2.0ºC or more sea surface temperature anomaly; two recorded episodes including 1982 and 1997
The 2015-2016 El Niño episode has already been classified as “strong,” with models indicating it could reach “very strong” status by the end of 2015.
Mike Halpert, deputy director of NOAA’s Climate Prediction Center says, “A strong El Niño is in place and should exert a strong influence over our weather this winter.”
Diagnostic discussions, in addition to the most recent winter outlook, released on October 15th, show a 95% chance this will episode peak by late fall/early winter before gradually weakening in the spring of 2016.
NOAA is able to achieve accurate predictions of El Niño episodes through a combination of dynamic models, based on physical processes, and statistical models, based on historical data. However, one question still remains: Will this become the strongest El Niño on record? Some meteorologists think so, but we will have to see how the season progresses before anything is known definitively.
Is this the strongest El Niño on record?
WUTV
experts debate whether this year’s El Niño will be the most disruptive
since 1950. Aired Tuesday, September 1, 2015 on The Weather Channel.
The Blob
By Bob Henson
During the winter of 2013-14, researcher Nicholas Bond of the University of Washington noticed a large pool of unusually warm water based in the south central Gulf of Alaska. Within the topmost 300 feet of the ocean, temperatures were as much as 2.5°C (4.0°F) above average in February 2014. By springtime, this warmth had spread east to the coasts of Washington and Oregon. In a report to the Washington state climatologist, Bond dubbed the region of unusually warm water “The Blob.”
The Blob had its origins in the preceding winter of 2012-13, but Bond found its signature was considerably stronger in 2013-14. By late 2014, two other regions of warmth had developed, one in the Bering Sea and another in the subtropics off Baja California and Mexico. The Blob’s warm anomalies (departures from average) expanded further in 2015, spreading southward toward the equator while growing in east-west breadth. Meanwhile, El Niño began to generate its classic signature of warm water along the equatorial eastern Pacific, just south of The Blob, by the middle of the year.
What led to The Blob?
High surface pressure and light winds helped produce the original midlatitude Blob. The persistence of the high pressure at both surface and upper levels was dubbed the Ridiculously Resilient Ridge of 2013 in December of that year by Stanford University doctoral student Daniel Swain at his California Weather Blog. Like the Blob itself, the Ridge persisted as an identifiable feature during 2014 and 2015 as its location evolved.
In one of Bond’s studies, he found that average sea level pressure in a region south of Alaska was higher than ever and surface wind speeds had dwindled to the second lowest on record. A relative lack of storminess reduced the amount of mixing between atmosphere and ocean and limited the amount of colder water flowing to this region from the north. In turn, this helped keep surface water over the Blob region from cooling as much as it usually would in autumn and early winter.
During the winter of 2014-15, storms continued to track far to the north across western Canada, leaving the West Coast largely high and dry and allowing the Blob to gradually expand.
What happens to the Blob and Ridge this winter?
Strong El Niño events, like the one now in place, tend to generate big winter storms across the Northeast Pacific. Forecast models already show an intensifying parade of storm systems over the Aleutians and Gulf of Alaska for the latter half of October. Over time, the wind and waves from these and subsequent storms should act to erode the original midlatitude Blob.
However, SSTs along the immediate coast from California to British Columbia may actually remain well above average this winter. That’s because powerful storms in the Northeast Pacific tend to foster strong south winds near the coast. Waters near the surface tend to move to the right of the winds above (a process called Ekman transport), so the strong south winds would push warmer water toward the coast and suppress any upwelling of cooler water.
Recent long-range models suggest that a La Niña could begin emerging in the wake of the current El Niño by mid-2016. If so, that would have a cooling effect on the waters off the U.S. West Coast.
Learn more about this phenomenon by reading Bob’s blog post on The Blob!
U.S. regional forecasts
Click on the map to view your regional forecast. Map by Madeline Rae
Environmental impacts
By Madeline Rae
Ocean sunfish have been observed in both 2014 and 2015
off the southern Alaska coast, hundreds of miles north of their usual
habitat. The heaviest bony fish in the world, ocean sunfish prefer
waters of 54°F or warmer. Crews from the Alaska Fisheries Science Center
caught the large ocean sunfish pictured here. Source: AFSC, via NOAA.
Crop Failures
El Niño episodes typically disrupt harvesting seasons, whether that means flooding farmland in South Africa or extreme drought in Australia. Over 59 million people in India were touched by famine when monsoon cycle was disrupted by the 1899-1900 El Niño episode.
Over time, erratic rainfall, flooding and drought have all contributed to massive crop failures in Africa, particularly affected sub-Saharan regions. Throughout this El Niño season, maize production has steadily declined. Maize is not only a nutritional staple for citizens of sub-Saharan Africa, but it is also the economic center for many communities.
The International Federation of Red Cross and Red Crescent Societies (IFRC) estimate 60 million people in sub-Saharan Africa do not have enough food to eat. This number is set to increase as El Niño decreases crop production, causing food scarcity and economic worries.
Corals turn a solid white when the algae they depend on for life, become stressed and leave. This stress comes from changes in temperature, light or nutrients. During an El Niño event, coral reacts to this shift in ocean temperature by expelling the symbiotic algae that lives within its tissues. Once the algae is expelled, the coral is bleached and vulnerable to other harsh marine conditions.
While coral can recover from mild bleaching, severe or long-term bleaching is deadly. Once these corals die off, entire reefs quickly degrade and erode, leaving fewer habitats with shoreline protection for fish and other marine life.
This is the third global coral bleaching event on record. The rising sea surface temperature during El Niño is endangering large areas of coral in the Hawaiian Islands, where bleaching is expected to continue at least through November. Other at risk areas include the Haiti, the Dominican Republic, Puerto Rico and the U.S. Virgin Islands. Climate models also indicate that this strong El Niño will cause bleaching in the Indian and southeastern Pacific Oceans through 2016.
Diminished Marine Life
Cold, nutrient-rich waters allow for a burst in marine life. However, when waters warm during El Niño episodes nutrient supply goes down, leading to progressively scrawnier plankton and microscopic-like creatures called copepods, the base species for the marine food chain.
Normally these plankton and later their predators, the copepods, are very fatty, giving nutrients to larger species on the food chain. In warm waters, upper level marine species are having to migrate long distances to find fattier prey.
Ocean sunfish, although tropical by nature, are now being seen off the coast of Alaska. They have been migrating north along the Pacific coast, along with many other equatorial fish, in search of more amenable waters. Some species of crab are hiding in deeper water, where it is colder and easier for them to survive.
Sea lion pups can’t get enough food, leading to a decline in the sea lion population. Jellyfish also have a tendency to die off during El Niño years because of a lack of nutrients.
The fishing industry is also taking a toll as fish populations are declining and the fish that survive are still comparatively small to those from typical years. Salmon fishermen in Alaska and ahi fishermen in Hawaii have both noted a drop in both size and number of fish caught.
The effects of this El Niño could last longer than we know. Because fish species take years to mature, the current lack of nutrients could mean that some species of fish will be leaner for years to come.
Around the world
By Dr. Jeff Masters
Worldwide weather conditions in an El Niño episode as compared to a typical season. Infographic by Jerimiah Brown
The unusually warm waters that El Niño brings to the Central and Eastern Pacific usually leads to well above-average hurricane and typhoon activity, with unusually strong storms. The strongest Eastern Pacific hurricane ever recorded, Category 5 Hurricane Linda, occurred during the strong El Niño year of 1997. Linda had sustained winds up to 185 mph and a central pressure of 902 mb on September 12th. In 2015, we’ve seen a record-active Central Pacific hurricane season, and a much more active than usual Eastern Pacific hurricane season and Western Pacific typhoon season.
Flooding in South America
The impact of El Niño on weather can often be the most severe in Peru and its surrounding countries. The unusually warm waters commonly cause record-breaking rains along the Pacific coast of equatorial South America, since warm air holds much more water vapor.
The two deadliest floods in Ecuador’s history occurred during strong El Niño events: in November 1982 (307 killed) and during October 1997 (218 killed.) Peru’s deadliest flood (518 killed) also occurred during the 1997 El Niño. As reported by AP, a United Nations-backed study said that the 1997 - 1998 El Niño cost Bolivia, Colombia, Ecuador, Peru and Venezuela nearly $11 billion.
Peru declared a pre-emptive state of emergency in July 2015 for 14 of its 25 states, appropriating about $70 million to prepare for the coming fall and winter rains. Authorities are clearing river beds of debris, reinforcing river banks with rocks and sandbags and fortifying reservoir walls.
El Niño and drought
The warm waters off the Pacific coast of Peru during a strong El Niño episode generate a column of rising air over the tropical Eastern Pacific. This air eventually sinks over tropical regions well to the east and the west of the Eastern Pacific to complete a huge circulation cell several thousand miles in diameter. Since sinking air warms and dries as it descends, areas of high pressure and drought tend to form in these sinking air regions.
Drought and subsequent fires in Indonesia are on track be their most expensive disaster in history, beating the $9.3 billion price tag of the 1997 - 1998 fires.
El Niño has already begun to cause droughts in parts of southern and northern Australia. This may cut as much as 1% off of the country’s GDP, said Andrew Watkins, supervisor of climate prediction services at the Australian Bureau of Meteorology, in an AP interview.
According to the U.N.’s Food and Agriculture Organization, dry weather caused by El Niño is responsible for declines of 60% in maize and 80% in beans across the Central American countries of El Salvador, Guatemala, Honduras and Nicaragua. Severe drought is also impacting eastern Puerto Rico, according to the latest U.S. Drought Monitor report. As of October 15, San Juan was 14” below their average precipitation for the date. On St. Barthelemy in the Lesser Antilles Islands, rainfall from January - September 2015 was only 8.65”--way short of their usual 23.74”.
Failure of the monsoon in India
The atmospheric circulation patterns brought on by an El Niño event usually cause much reduced monsoon rains in India. According to EM-DAT, the International Disaster Database, more than 4.2 million people died in India between 1900 - 2014 due to droughts from failed monsoon rains, primarily during El Niño years. As of October 1, 2015, this year’s monsoon had brought rains 14% below normal to India, in line with pre-season predictions of a deficient monsoon.
Check the Dr. Jeff Masters’ Blog to find more of Dr. Masters’ analysis on the global impact of an El Niño episode.
Click on the map markers above to see how some other countries are impacted by El Niño. Map by Madeline Rae
Safety tips
By Madeline Rae
Before El Niño hits, here are a few prep tips:
1. Inspect the Roof
If you live in an older house, it might be prudent to inspect your roof, or hire a contractor to check for any signs of cracks, holes or loose tiles that could lead to serious leaks during a storm.
2. Clean the Yard
During any storm, wind damage can cause property damage and personal injury. If you know El Niño is sending a storm your way, make sure you secure all outdoor furniture, or move it indoors. Additionally, rid your yard of sideways trees, dead branches or other loose yard debris that could be picked up by storm winds.
Large bare areas could be sources for mudflows during storms. Avoid having these areas in your yard by putting down mulch and vegetating these areas with native plants. If you still have concerns about mudflows or slope stability, plastic sheeting can be placed on slopes and secured with sandbags to prevent erosion. Sandbags can also be used to build a barrier around low areas to prevent flooding.
4. Check Drains
Flooding is one of the most common hazards during an El Niño season. Make sure all of your drains and gutters are clear of debris and function properly to avoid exacerbating flooding issues. If you ever see a storm drain that is damaged or obstructed, be sure to contact your local Department of Public Works right away.
5. Build an Emergency Kit
The Federal Emergency Management Agency (FEMA) maintains a list of basic supplies that should be included in every family’s emergency kit. View additional information on emergency preparation for businesses, commuters, pet owners, seniors and people with disabilities.
6. Have a Plan
Make sure your family has a plan! Use FEMA’s family emergency plan template to create a plan that works for you. More tips on communication and preparedness can be found You can also find more tips on safety at Weather Underground’s extreme weather preparedness page.
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