Technical Bulletin
A publication of the LG Seeds Agronomy department
Issue 270: February 2016
El Niño / La Niña
Mark Seem, Technical Agronomist, CCA
There has been much in the press recently about El Niño and La Niña. These two phenomena are greatly
responsible for the weather we see in the corn belt from year to year. Sometimes we need to take a step
back and review what these weather influencers are, and how they affect our seasonal cropping patterns.
The successive El Niño / La Niña events can be associated with record rainfall and some of the biggest floods
and largest snowstorms in living memory. The cycle has also resulted in years of severe drought in many
parts of the country.
What are El Niño and La Niña?
El Niño and La Niña are global climate events and occur naturally in cycles over time. They occur when the
Pacific Ocean and the atmosphere above it change from their neutral state for several seasons. El Niño
events are associated with a warming of the central and eastern tropical Pacific, while La Niña events are the
sustained cooling of these same areas.
Why are they called El Niño and La Niña?
The warming trend was noted by ancient Peruvian fisherman as occurring around Christmas time – therefore
the phenomenon was dubbed El Niño (when capitalized, “the little boy” becomes “the Christ Child” in
Spanish). Although “la niña” refers to a young girl, the capitalized term La Niña was not named the same way,
researchers chose the feminine name to differentiate relationships between warming and cooling events of
the eastern tropical Pacific.
El Niño–Southern Oscillation (ENSO) explained
Changes in the ocean temperature and the above atmosphere occur in a cycle known as the El Niño–
Southern Oscillation (ENSO). This interaction, which reinforces each other, creates a ‘feedback loop’, which
amplifies small changes in the
state of the ocean into a major
ENSO event. When it is clear that
the ocean and atmosphere are
fully coupled, an ENSO event is
considered established.
El Niño–January 2016
Image courtesy Dan Pisut, NOAA NNVL, www.climate.gov
lgseeds.com
The winds around the equator in
the Pacific Ocean usually move
from east to west, pushing the
surface of the ocean towards
south Asia, as the warm water
evaporates, moisture filled air
produces the monsoon season in
Asia and Australia. This is called
the neutral phase. El Niño occurs
when, for unknown reasons, these
trade winds stop moving, and the
ocean warms. The current event
©2016 LG Seeds
started in roughly June of 2015. Although the start of a warming event is unpredictable, the consequences
are very predictable, and the life cycle lasts approximately 12 months. These cycles occur every 2 to 7 years.
Once the trade winds stop blowing, weather patterns reverse: Asia & Australia experience drought, the west
coast of South America experiences severe rainy seasons, and, for North America – the jet streams are
altered. This allows heavy rains to visit California, warm air is pushed across the northern United States and
unseasonable warm weather is experienced on the East Coast. On average, the Gulf coast is wetter, the Ohio
Valley and Corn Belt in general become drier and drought prone. These effects can last for an extended
period of time, much longer than the actual event itself. Clearly the effects of El Niño are felt this winter, as
(for the most part) the winter has been mild across the northern US, and wet from Texas to Florida (Note:
December was the warmest December on record)
Severity of an El Niño event is determined by the temperature change that occurs at the ocean’s surface. A
“moderate” event results from an average 1C rise in temperature, while a “strong” event occurs when that
rise in temperature is over 1.5. The strongest El Niño events on record are 1982-83 and 1997-98, with
surface ocean temperatures peaking at 2.2 to 2.4C. The current El Niño is most likely going to set a new
record and become the strongest El Niño on record.
La Niña explained
Simple explanation – La Niña is the opposite of El Niño. When the trade winds resume their east-to-west
flow, ocean water temperatures often will fall below the norm. Usually not as much of a drop, as the
preceding rise. The strongest La Niña recorded was in 1973-1974 and again in 2010-2011. A problem with La
Niña is that it can persist much longer than El Niño. The longest La Niña occurred from mid-1998 to early
2001. La Niña can form independently of an El Niño, but often happens immediately after the warming event,
perhaps to overcome the changes brought on by El Niño. The cooling event is often caused by a
strengthening of the trade winds, and as a consequence can mimic the neutral state of the ocean, lasting
longer than El Niño.
Illustration courtesy of NOAA
When in the La Niña phase, weather in North America is generally warmer in the southeast and cooler in the
northwest.
lgseeds.com
©2016 LG Seeds
Effects of the El Niño and La Niña events
Events are usually named as the El Niño / La Niña years of occurrence. The effects of the economic impact of
the 1982–83 El Niño / La Niña was many billions of dollars worldwide, from droughts, fires, flooding, and
hurricanes. U.S. crop losses from the 1982–83 El Niño / La Niña were projected in the neighborhood of $10–
12 billion. The extreme drought in the Midwest Corn Belt of the United States during 1988 has been linked to
the La Niña of 1988 that followed the El Niño event of 1986–87.
In the United States, impacts of El Niño are most dramatic in the winter. El Niño produces winters that are
generally mild in the northeast and central United States and wet over the south from Florida to Texas,
northwestern regions of the United States can be abnormally warm. It has been concluded by researchers
that: 1) the western United States experiences above-normal precipitation 81% of the cases for an El Niño
season that runs from April to October. 2) In the southeastern United States above-normal precipitation was
recorded for 81% of the cases for an El Niño season that begins in October of the ENSO year and concludes in
March of the following year. 3) For temperature anomalies during El Niño conditions in North America, the
Pacific Northwest shows warmer temperatures in 81% of the years while the southeastern United States
shows below-normal temperatures 80% of the time. 4) During stronger events of the El Niño / La Niña cycle,
the United States experiences flooding and severe storms in some regions; droughts and heat waves in other
areas. 5) During the summer, heat waves and below-normal precipitation bring drought, and possible crop
failures.
Summary and Predictions
Weather patterns vary greatly from year to year and from season to season. The El Niño / La Niña cycle is
only one influencer of our weather, albeit a major influencer.
Temperatures:
The current long range NOAA forecast is for temperatures to be above normal for the northern corn
belt thru the early spring, giving way to cooler than normal temperatures in the southern High Plains. As the
El Niño / La Niña cycle turns more neutral later in the spring, above normal temperatures are expected with
increasing odds of higher temperature across the corn belt thru the fall of 2016, a result of an expected La
Niña, as the current El Niño event subsides, including a possibility of cooler than unusual temperatures in the
winter of 2016-17.
Precipitation:
The spring outlook from NOAA expects higher odds of wet weather across the central and southern
plains. This is contrasted with expectations of reduced precipitation in the Ohio Valley, Great Lakes regions
and northern plains. It is suggested that Ohio and east will escape the early dry spell, but eventually will
become drier over time. An expected La Niña event in the summer/fall of 2016 allows for the potential of
below- moisture conditions across the central Corn Belt.
The forecast from WeatherTrends360 published in late July 2015 states: “A moderate to severe drought will
encompass a large area from Montana to Indiana into the Middle Atlantic States by summer 2016”
Sources and Additional Information:
1.
2.
3.
4.
5.
6.
http://www.weathertrends360.com/Blog/Post/Strongest-El-Nio-in-100-years-Here-are-some-predictions2506
http://www.cpc.ncep.noaa.gov/products/predictions/long_range/fxus05.html
http://www2.ucar.edu/news/backgrounders/el-nino-la-nina-enso
http://www.atmos.washington.edu/gcg/RTN/rtnt.html#part2
https://www.climate.gov/news-features/featured-images/el-niño-warmth-continued-during-january-2016
http://oceanservice.noaa.gov/facts/ninonina.html
Note: The information in this issue is based upon field observations and third party information. Since variations in local conditions may affect the
information and suggestions contained in this issue, LG Seeds disclaims legal responsibility therefore. Always read and follow label instructions.
LG Seeds and design are trademarks of SCA Limagrain.
lgseeds.com
©2016 LG Seeds