Forecaster: Two phenomena responsible for world's bizarre weather
A graphic outlining sea temperature anomalies the first week in January shows drops in the Pacific as air temperatures rise between the U.S. and Europe (continents in gray). La Niña and the North Atlantic Oscillation are to blame, an expert says.
January 13th, 2011
03:35 PM ET

Forecaster: Two phenomena responsible for world's bizarre weather

The catastrophic weather events taking place across the globe – from Brazil’s and Australia’s flooding to the Eastern United States’ heavy snowfall – have two likely explanations.

Tony Barnston, lead forecaster at Columbia University’s International Research Institute for Climate and Society, said two phenomena – La Niña and the North Atlantic Oscillation – are likely responsible for the patterns we’re seeing.

Though La Niña is different every time, it can be simply defined as a drop in water temperature in the eastern and central tropical Pacific Ocean. This particular La Niña appeared in July, Barnston said, and will last through spring.

During La Niña, there is less rainfall in the tropical Pacific and a horseshoe pattern of warm water typically forms in the North Pacific, the coast of Southeast Asia and the seas around Indonesia and Australia (check out the graphic above).

In this case, though, “the whole globe looks to be compensating,” Barnston said, noting that it’s difficult to determine if  La Niña spawns individual weather events.

While Southeast Asia and Australia can typically expect warmer oceans and more rainfall during La Niña, the affected area stretches farther west this year and includes Sri Lanka and the southern tip of India, Barnston said.

There is presently a massive rescue operation under way in Sri Lanka to save victims of flooding that has already killed at least 13 people. Floods have killed another 40 people in the Philippines, and Australia has been inundated with deadly flooding reportedly estimated to cover an area the size of France and Germany combined. To the east of La Niña, South America's north coast has been slammed with rain, and hundreds have been killed in Brazil's flooding and mudslides.

La Niña usually means warmer temperatures in the United States, particularly the Southeast, but this year the North Atlantic Oscillation is trumping La Niña.

Since November, we have been in the negative phase of the North Atlantic Oscillation, Barnston said, meaning that air temperatures between the eastern U.S. and Europe will drop. This causes temperatures to rise in places like northeast Canada, Greenland and Iceland, as the mercury drops on thermometers in the eastern U.S.

Weather experts call it a see-saw pattern, and it will eventually affect water temperatures, though that’s a secondary effect, Barnston said.

So while La Niña would normally mean dryer, warmer weather for folks in the southern United States, “the North Atlantic Oscillation has superseded the La Niña” this year, bringing El Niño-like winter temperatures and snow to the Southeast, he said.

CNN meteorologists reported earlier this week that snow was present in every U.S. state but Florida.

Though La Nina typically lasts until April or May, the North Atlantic Oscillation can move from a negative to positive phase mid-winter. Barnston said the Southeast “could be warmer and dryer than normal later this year if the North Atlantic Oscillation ceases and desists.”

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Filed under: Australia • Brazil • India • Indonesia • Philippines • Sri Lanka • Tropical weather • U.S. • Weather • Winter weather
soundoff (963 Responses)
  1. fastball

    If you still use the phrase "global warming" in any statement, you obviously haven't been paying attention to anything new in the past decade. Therefore, your contributions to this board are noted – and will be given with the same attention that you pay to new developments in science.

    January 14, 2011 at 11:20 am | Report abuse |
  2. David

    Freaking world is going to end before my pension kicks in and before I can go back to Vegas. This sucks.

    January 14, 2011 at 11:22 am | Report abuse |
  3. baruch

    What the article doesn't say is that the severity of the change in the North Atlantic Current and temperature is related to the BP oil disaster. The chemicals they used have expanded the dead zone in the Gulf of Mexico, which waters flow into the North Atlantic, so the salinity and viscosity are slightly altered, and that effects the movement of warm waters northward, reducing that heat transfer, thus a colder winter than usual in Europe and in the southern US.

    January 14, 2011 at 11:23 am | Report abuse |
  4. Renato Trevine

    La Niña usually means warmer temperatures in the United States.............maybe only on US, all the rest of the world knows that la nina means the little girl, I feel sorry for CNN to employ this tip of employee...........tchau bye bye

    January 14, 2011 at 11:26 am | Report abuse |
  5. Casual Observer

    OK, I get it the climate is likely changing..........however, when environmentalists or climatologists can show me the link between the exhaust of my Harley Davidson and the shrinking ice-caps on MARS we have something to talk about.

    January 14, 2011 at 11:26 am | Report abuse |
    • Catie

      Oh my gosh, finally, a reasonable person !!!

      January 14, 2011 at 1:58 pm | Report abuse |
  6. Lane

    I don't know about the rest of you, but I could use a little "Global Warming" right about now, it's freezing out here!

    January 14, 2011 at 11:27 am | Report abuse |
  7. all american

    there is nothing anyone can do.Go about your bussiness as usual. Maybe buy a warmer sweater or a tank top. rest ashured times are changing. the planet is changing, call your parents and tell them you love them. and we are going to be okay. this is the middle of an ice age.

    January 14, 2011 at 11:27 am | Report abuse |
  8. Kana

    Maybe it's because of the earth wobble and zodiac chart being off?

    January 14, 2011 at 11:29 am | Report abuse |

    perhaps if the scientist knew that methane degrades to formaldehyde and water vapor on its way to carbon dioxide, they would point in another direction- the tremendous amount of methane and heat released to our seas and airs during the BP breech. We are talking about the rise in moistur,e not where it ends up, and ocsillation does not manufacture water vapor; only methane does that.

    January 14, 2011 at 11:30 am | Report abuse |

    Perhaps if the scientists knew that methane degrades to formaldehyde and water vapor on its way to carbon dioxide, they would point in another direction- the tremendous amount of methane and heat released to our seas and airs during the BP breech. We are talking about the rise in moisture not where it ends up, and oscillation does not manufacture water vapor; only methane does that. they might then also point to the formaldehyde for bird and dish deaths too.

    January 14, 2011 at 11:31 am | Report abuse |
  11. Sam

    What about the volcano from the summer? Wouldn't that have an effect on weather patterns? Look up "The Year Without A Summer" (1816).

    January 14, 2011 at 11:35 am | Report abuse |
  12. steven

    I think the world is ending now; this goes to show you that we should follow Gore and build on the moon so when it happens we will still be able to beat the aliens in 2034. And the world will be ending in 2013 Duh. Those Mians forgot to carry the 4 in the equation. Were really in the year 1967.

    January 14, 2011 at 11:37 am | Report abuse |
    • 1967?

      cool, I'm off to the local Dodge dealer with a check for $3,000 for a new Dodge Coronet R/T 426 Hemi....

      January 14, 2011 at 2:11 pm | Report abuse |
  13. Michael

    I see a lot of people still in denial of GW - go look up the term "radiative forcing" and see for yourself why CO2 is one of the largest contributors to this effect.

    January 14, 2011 at 11:39 am | Report abuse |
    • Catie

      Michael, the atmosphere loves CO2, it gobbles it up like tortilla chips. Denial about GW, oh lord you are a lost soul arent you?

      January 14, 2011 at 1:51 pm | Report abuse |
  14. AC

    OK, now the weather people are trying to blame mexicans, telling us that this chicana "El Nina" is causing all the snow in the East Coast, because of her brother "El Nino" who likes warmer weather in the West Coast or Southwest. What a bunch of putos! Anyway Sri from India, start praying for the basics in India, like clean water, food, crops and housing, stuff like that. BBQ this weekend in SoCal, high today 76.

    January 14, 2011 at 11:42 am | Report abuse |
  15. DDDDD

    Jesus is coming soon.........repent for the kingdom of heaven is at hand....and no one knows the day or the time, no one but the father

    January 14, 2011 at 11:44 am | Report abuse |
    • Wzrd1

      Nope, I just checked with him. He said that there are too many idiots here to bother with, people who keep blaming him for the weather and telling everyone he'll be here soon.

      January 14, 2011 at 11:52 am | Report abuse |
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