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. Southerner

    Florida is the only state without ground snow? Did you forget Hawaii?

    January 14, 2011 at 10:28 am | Report abuse |
    • adam

      Hawaii has significant snow on two mountains.

      January 14, 2011 at 10:35 am | Report abuse |
    • maine liberal

      havent you been listening to the teaparty: Hawaii isnt part of the US 🙂

      January 14, 2011 at 10:38 am | Report abuse |
  2. Sci-nut

    Yes, climate change happens every day. I want to see imperial data that spans more than human records... BTW most of the data is only 1-200 years and how accurate were the first 50 – 75 years? Also much of the data on gases in the air have not been taking into consideration the large volcanic explosions or constant off gassing of active volcano's. Some of the data only covers 20 – 30 years. How old is the earth again, oh yea sorry 4.6 billion years. So we see the earth went through cycles in the past over long periods. So now we are going to look at a 460 year segment that is 0.00001%. Hmm, not very convincing, That equates to finding 100 dead citizens on beaches around the world and saying we should close the beaches of the world because it is killing us. Perhaps we should get out of the practice of chasing the funding. PLEASE STOP DRINKING CARBONATED BEVERAGES each time you do you release carbon dioxide into the atmosphere and are hurting our planet...

    January 14, 2011 at 10:30 am | Report abuse |
  3. ED

    What bizarre weather???? Hey CNN, it's called winter. Another scratching-for-copy fabricated news filler.

    January 14, 2011 at 10:30 am | Report abuse |
  4. Semper Fi

    Rhythm of the earth. No more no less. It is ego centric to think humans have anything to do with this.

    January 14, 2011 at 10:31 am | Report abuse |
    • Secos77

      Corporate America has sold you a bill of goods. Look at your history. Humans have dammed mighty rivers, diverting water and creating desert where there once was plentiful that farming corporations can plant crops somewhere else. We've filled the air with pollution, wiping out forest regions (our source of oxygen) and affecting the health of plants, animals, and humans. Climate Change will be gradual, not overnight. Sort of like the frog that sits in the pot of heating water and doesn't jump out, but gets lulled to sleep and its demise.

      January 14, 2011 at 10:48 am | Report abuse |
    • Catie

      Thank you for your service, I am guessing.
      Yes, I agree totally with you.
      I am pretty sure God planned for everything we are doing. He knew we would have dams, industry, autos, even nuclear weapons. He said He was coming back, I think He is planning on coming back to something

      January 14, 2011 at 2:06 pm | Report abuse |
  5. Damion

    This is not an explanation, at least not to suit my modest knowledge of science. This is merely a categorization of observations using a meteorologist's verbiage. What is really going on? What's the root cause of all this? Will it continue?

    January 14, 2011 at 10:32 am | Report abuse |
  6. Will S

    Weather and climate aren't the same thing.

    January 14, 2011 at 10:33 am | Report abuse |
  7. Robert

    The explanation is simple: more CO2 in the atmosphere=warmer air temperature=more seawater evaporation=more water vapor in the air=more rain in the summer and snow in the winter=more extreme weather events=higher food prices=social instability=failed governments=migrations, wars, famine, disease=collapse of civilization=extinction?.

    But don't worry there a new set of judges on American Idol!

    January 14, 2011 at 10:34 am | Report abuse |
  8. maine liberal

    Globe to skeptics snow does not mean its cold,

    Snow occurs as it did this past week in Maine for the noreaster when the warm water of the ocean hits the cold front.
    last year winter in maine was over in early february and we were plabting vegetable garden in march.

    Global warming is a change of just 4 degrees of average tempature. this does not mean that we have have palm trees in new england. It does mean that we will have wild weather swings.

    The scientific method is observe, measure, predict and repeat.

    Those of you saying that the earth is to vast for man to influence are the next generation of those saying the oceans are too vast for man to pollute.

    January 14, 2011 at 10:34 am | Report abuse |
  9. Will S

    If you want "Imperial" (sic. empirical) data of climate change beyond "human records" (whatever that means), read the full IPCC report. It is all in there. If you don't trust that, delve into the thousands of individual research papers on which it was based.

    January 14, 2011 at 10:36 am | Report abuse |
  10. Secos77

    "Global Warming" is a misnomer. If you raise the carbon dioxide levels in the atmosphere, you get the Greenhouse Effect, the same idea as when a car's interior heats up in the sun with windows closed. That's physics. Not opinion. The Earth's atmosphere is warming creating Climate Change. To the simpleton this means EVERYTHING gets hot at once. No. You get weather extremes because of the additional heat energy in the atmosphere. Some areas are rising in temperature (polar regions for example) while some see extreme weather of all sorts. But as the temperature slowly rises and the ice caps melt, hold on to your seats. What we've seen is nothing compared to what will be......thanks to our addiction to the gunk left behind the dinosaurs.

    January 14, 2011 at 10:36 am | Report abuse |
  11. zavi13

    "Snow present in every state except Florida?" say meteorologists. That must have chilled the beach babes and surfer dudes at Waikiki? Possibly in every continental US state except Florida?

    January 14, 2011 at 10:41 am | Report abuse |
    • Generalist

      There is snow on the Big Island. Check the Mauna Kea snow report.

      January 14, 2011 at 11:53 am | Report abuse |
  12. Rick

    Thanks for the Graphic, that really cleared things up. CNN your terrible.

    January 14, 2011 at 10:42 am | Report abuse |
  13. Terry

    Every year, right about now, we experience this thing called winter. Some years it snows, some years it rains, and some years it just gets really cold. This too will pass.

    January 14, 2011 at 10:45 am | Report abuse |
  14. Darlene Buckingham

    Bioengineering aka chemtrails.

    January 14, 2011 at 10:46 am | Report abuse |
  15. think smart

    I have a better explanation..... In th U S la nina became lesbian an the nino gay,this is why the change in the weather....

    January 14, 2011 at 10:51 am | Report abuse |
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