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. Antonio Rosado Junior

    This tragedy concentrated in southeastern Brazil. (Minas Gerais and Rio de Janeiro) because of the effect el-nina. The catastrophe in the region of mountain ranges in Rio de Janeiro(Petropolis, Nova Friburgo and Teresopolis) still continues because it rains there. Today (01/14) more than 450 confirmed dead. The total is more than 1,000 missing beneath rocks.

    January 14, 2011 at 6:33 am | Report abuse |
  2. AK

    We are experiencing severe floods in South Africa as well, why is Africa left out again?

    January 14, 2011 at 6:34 am | Report abuse |
  3. Antonio Rosado Junior

    More informations about Brazil in twitter @arjcss and facebook: arjcss

    January 14, 2011 at 6:36 am | Report abuse |
  4. Brad

    Crazy weather has always occured on earth. Remember, mother earth is the BADDEST ONE OF ALL. But, the human population has never been so high and that's why it is such a big deal.

    January 14, 2011 at 6:37 am | Report abuse |
  5. John

    Why not just go back to last year, the year before, or the year before that and re-post the same story? Every year you, and every other major news organization, run a story about "This Year's Bizarre Weather". Did you ever stop to think that weather is, well, bizarre? Every year, I also hear we have a La Nina or El Nino. Areas around the globe having temps that deviate widely from the average? It's an AVERAGE, folks!

    January 14, 2011 at 6:45 am | Report abuse |
  6. anglo-rights

    Damm... and I thought they were gonna say it was caused by Al Gore creating a new internet that disproved the countless theories that abound over global warming, while he pockets billions. Actually the weather here in Florida has returned to an almost normal state this winter. Problem is, it hasn't been normal in so long that no one recognizes normal, as being normal.

    January 14, 2011 at 6:48 am | Report abuse |
  7. David F Pawlowski

    At least one scientist in the climate debate has pointed out that the earth's weather is influenced by the small variability of the sun's output and the ebb and flow of how many cosmic rays make it to earth depending upon where the sun is along the solar cycle. Given we are still at a very low period of the solar cycle and the change in magnetic field strength it begs the question could we see change in regional weather patterns when the protective magnetic field breaks down and the earth's surface and thin atmosphere experiences an increase in high energy particles at lower levels. If the magnetic field plays a role on meterology, and it changes signficantly, things could get very interesting. Let's hope NOAA and the "JASONs" at the MITRE corporation are funded and asking the questions.

    January 14, 2011 at 6:52 am | Report abuse |
  8. ravenlynne

    Cue the anti-global climate change ostriches, the pro global climate change freaks and the end of the world lunatics.

    January 14, 2011 at 6:54 am | Report abuse |
  9. jt

    As we float on this ball of dirt that travels through the vastness of space, remember one thing please......Weather Happens!

    January 14, 2011 at 6:59 am | Report abuse |
  10. Carlos

    The Bible says that at the end of time we are going to be seeing things that we hadn't seen...so for me I know Jesus is coming and the end for these world is just around the corner...

    January 14, 2011 at 7:02 am | Report abuse |
    • jt

      Just the beginning:.....Mar 13:8 For nation shall rise against nation, and kingdom against kingdom: and there shall be earthquakes in divers places, and there shall be famines and troubles: these are the beginnings of sorrows

      January 14, 2011 at 7:04 am | Report abuse |
    • Ha

      Have fun waiting for something that will never come.. the rest of us will be out actually trying to do something

      January 14, 2011 at 3:26 pm | Report abuse |
  11. tricey

    wow , everybody has a comment . Well i hope everybody'sis praying right now , the devil has all of u right where he wants u , confussed... To tell story teller that say's he doesn't believe in our god , i pray for u deeply and ur family that u will see the light before it's too late ... He is not just our god , he is also ur god , and guess what he loves you too .. I can't sit here and say what's going to happen , but true belief is in the heart , u know like when ur a kid and u get that feeling all through ur body when christmas comes , or u know ur bout to have a birthday , the excitment u feel , that's what i feel when i hear the word of god , it's a natural feeling of joy , and that is deffently real ... I'm sorry u feel that way , just one question i have to ask, how do u think u was created if u do not believe , along with the world and evrything in life itself??? Just confussed there ... One more thing before i leave , the news , the t.v. , the people , the devil loves gossip , and so that will spead like wild fire , i pray for all of u ... God bless.

    January 14, 2011 at 7:07 am | Report abuse |
  12. BIG_CHUCK

    Chuck Norris was taking a shower.

    January 14, 2011 at 7:12 am | Report abuse |
  13. Bob Saysmore

    The brainiacs are certainly on the loose with this topic!

    January 14, 2011 at 7:15 am | Report abuse |
  14. Richp, Easton, Pa

    I tell you it's Bushes fault... or the earth is trying to get rid of progressive city people....

    January 14, 2011 at 7:27 am | Report abuse |
  15. Frost E Snowman

    I smile as I realize I live in a place that is well above sea level, not next to a potentially raging river, not in a place where a hurricane can roar up unexpectedly...or be all that strong if it did, and tornadoes are few and generally weak. The only problem is that the people there seem fairly unremoved from the civil war era in their mannerisms and educational level.+

    January 14, 2011 at 7:31 am | Report abuse |
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