The 2010–2012 La Niña event was one of the strongest on record. It caused

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

to experience its wettest September on record in 2010, and its fourth-wettest year on record in 2010. It also led to an unusual intensification of the

Leeuwin Current The Leeuwin Current is a warm ocean current which flows southwards near the western coast of Australia. It rounds Cape Leeuwin to enter the waters south of Australia where its influence extends as far as Tasmania. Discovery The existence of the ...

, the

2010 Pakistan floods The floods in Pakistan began in late July 2010, resulting from heavy monsoon rains in the Khyber Pakhtunkhwa, Sindh, Punjab (Pakistani province), Punjab and, Balochistan, Pakistan, Balochistan regions of Pakistan, which affected the Indus Riv ...

, the

2010–2011 Queensland floods A series of floods hit Queensland, Australia, beginning in December 2010. The floods forced the evacuation of thousands of people from towns and cities. At least 90 towns and over 200,000 people were affected. Damage initially was estimated at A ...

, and the

2011 East Africa drought Eleven or 11 may refer to: *11 (number) * One of the years 11 BC, AD 11, 1911, 2011 Literature * ''Eleven'' (novel), a 2006 novel by British author David Llewellyn *''Eleven'', a 1970 collection of short stories by Patricia Highsmith *''Eleven'' ...

. It also helped keep the average global temperature below recent trends, leading to 2011 tying with 1997 for the 14th-warmest year on record. This La Niña event also led to above-average

tropical cyclone A tropical cyclone is a rapidly rotating storm system with a low-pressure area, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depending on its locat ...

activity in the

North Atlantic Ocean The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...

during the

2010 The year saw a multitude of natural and environmental disasters such as the 2010 Haiti earthquake, the Deepwater Horizon oil spill, and the 2010 Chile earthquake. The 2009 swine flu pandemic, swine flu pandemic which began the previous year ...

2011 The year marked the start of a Arab Spring, series of protests and revolutions throughout the Arab world advocating for democracy, reform, and economic recovery, later leading to the depositions of world leaders in Tunisia, Egypt, and Yemen ...

, and

2012 2012 was designated as: *International Year of Cooperatives *International Year of Sustainable Energy for All Events January *January 4 – The Cicada 3301 internet hunt begins. * January 12 – Peaceful protests begin in the R ...

hurricane seasons, while the Eastern and Western Pacific experienced record low activity in 2010 and below average activity in 2011.

Meteorological progression

The 2009–2010

El Niño EL, El or el may refer to: Arts and entertainment Fictional entities * El, a character from the manga series ''Shugo Chara!'' by Peach-Pit * Eleven (''Stranger Things'') (El), a fictional character in the TV series ''Stranger Things'' * El, fami ...

event started in the Pacific Ocean during July 2009, before it reached it peaked during December and broke down during the first quarter of 2010. The climate of the Pacific Ocean subsequently returned to neutral conditions by the end of April, while

climate models Numerical climate models (or climate system models) are mathematical models that can simulate the interactions of important drivers of climate. These drivers are the atmosphere, oceans, land surface and ice. Scientists use climate models to stu ...

used and developed by various meteorological agencies, subsequently started to show signs that a

La Niña LA most frequently refers to Los Angeles, the second most populous city in the United States of America. La, LA, or L.A. may also refer to: Arts and entertainment Music *La (musical note), or A, the sixth note *"L.A.", a song by Elliott Smit ...

event would develop later in 2010. Over the next month the Pacific Ocean started to show various signals that indicated a La Niña event was developing and as a result, a La Niña watch was issued by the United States

Climate Prediction Center The Climate Prediction Center (CPC) is a United States federal agency that is one of the National Centers for Environmental Prediction, which are a part of the National Oceanic and Atmospheric Administration's National Weather Service. CPC is hea ...

during their June 2010 ENSO diagnostic discussion. As the ocean's surface temperature cooling progressed, more colder anomalies appeared at the

International Date Line The International Date Line (IDL) is the line extending between the South and North Poles that is the boundary between one calendar day and the next. It passes through the Pacific Ocean, roughly following the 180.0° line of longitude and de ...

rather than over eastern Pacific, what allowed calling this event as a '' Modoki'' one.

Impacts

Australia experienced its second- and third-wettest years, since a record of the rainfall started to kept during 1900.

Winter Winter is the coldest and darkest season of the year in temperate and polar climates. It occurs after autumn and before spring. The tilt of Earth's axis causes seasons; winter occurs when a hemisphere is oriented away from the Sun. Dif ...

saw above average snowfall in much of the

Western United States The Western United States (also called the American West, the Western States, the Far West, the Western territories, and the West) is List of regions of the United States, census regions United States Census Bureau. As American settlement i ...

as well as the

Midwest The Midwestern United States (also referred to as the Midwest, the Heartland or the American Midwest) is one of the four census regions defined by the United States Census Bureau. It occupies the northern central part of the United States. It ...

. With the exception of the Southern Rockies,

Western Mountains The Western Mountains or Western Hills ( ''Xi Shan'') are a scenic mountain area located 12 km to the west of Kunming, Yunnan, China. They are formed by the Huating, Taihua and Luohan mountain ranges rising above the eastern and northern banks of ...

saw snowpack totals above 180% of normal. Meanwhile, the

2011 Groundhog Day blizzard The 2011 Groundhog Day blizzard was a powerful and historic winter storm that affected large swaths of the United States and Canada from January 31 to February 2, 2011, especially on Groundhog Day. During the initial stages of the storm, some me ...

caused record snowfall in

Chicago Chicago is the List of municipalities in Illinois, most populous city in the U.S. state of Illinois and in the Midwestern United States. With a population of 2,746,388, as of the 2020 United States census, 2020 census, it is the List of Unite ...

and forced the city to shutdown. Because this was a La Niña, it brought

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

the wettest December on record and the summer of 2011 was California's wettest. The Pacific Northwest saw 2011 being one of the coolest, wettest years on record, with temperatures still in the 50s and rain/snow mix even in May. The Midwest and

Northeastern United States The Northeastern United States (also referred to as the Northeast, the East Coast, or the American Northeast) is List of regions of the United States, census regions United States Census Bureau. Located on the East Coast of the United States, ...

also experienced an extremely wet 2011, leading to flooding across the

Mississippi River The Mississippi River is the main stem, primary river of the largest drainage basin in the United States. It is the second-longest river in the United States, behind only the Missouri River, Missouri. From its traditional source of Lake Ita ...

Missouri River The Missouri River is a river in the Central United States, Central and Mountain states, Mountain West regions of the United States. The nation's longest, it rises in the eastern Centennial Mountains of the Bitterroot Range of the Rocky Moun ...

, and the Ohio River. The La Nina is also blamed for the record tornado activity across the Southern U.S during Spring 2011, especially the Super Outbreak, which is the largest and costliest tornado outbreak in recorded history, as well as being one of the most violent and one of the deadliest. The

2010–2013 Southern United States and Mexico drought The 2010–2013 Southern United States and Mexico drought was a severe to extreme drought that plagued the Southern United States, including parts of Texas, Louisiana, Arkansas, Mississippi, Alabama, Georgia, South Carolina, North Carolina, ...

caused low streamflow, agricultural distress, and wildfires throughout the Southern Plains and Georgia. The worst effects were felt in Texas, where 2011 was the driest calendar year on record as well as the third warmest.

Notes

References

{{DEFAULTSORT:2010-2011 La Nina Event

La Nina LA most frequently refers to Los Angeles, the second most populous city in the United States of America. La, LA, or L.A. may also refer to: Arts and entertainment Music *La (musical note), or A, the sixth note *"L.A.", a song by Elliott Smit ...

El Niño-Southern Oscillation events