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Statistically Speaking: Tut, Tut, Looks Like …

by Bill Chameides | January 18th, 2011
posted by Erica Rowell (Editor)

Permalink | 2 comments

 


From Guatemala (pictured here in July 2010) to Pakistan to Germany, Borneo, Australia and many places in between, 2010 was wet, wet, wet — with precipitation levels setting many a record.

Have you noticed it’s been rather wet out there?

2010 Was an Exceptional Year for Rainfall

How so?

  • The year 2010 saw its share of record-breaking deluges with the wettest regions includingmost of Central America, much of India, southwestern China, eastern Asia, Borneo, and parts of Australia. Here are just some of the year’s most extreme events:
    • The worst flooding in Pakistan since 1929 (more info here, here, and here);
    • Germany’s wettest August since 1901;
    • The worst flooding in Southwestern France since 1827;
    • The worst flooding in Israel, Egypt and Kenya in more than a decade;
    • Mexico’s wettest July since 1941;
    • Australia’s wettest spring since record-keeping began in 1900, and its third wettest year on record. (See more examples of 2010’s extremes here.)
  • While many parts of the globe were ravaged by drought, the year 2010 still broke the record for the wettest year for globally averaged precipitation since 1900. (See graphic directly below.)

Source: NOAA

2011 Off to an Inauspicious Start With Massive Floods

AUSTRALIA – As 2011 takes off, Australia’s wet December — as news images have shown in graphic detail — has engulfed large parts of Queensland, wreaking havoc for thousands of Australians.

BRAZIL – While nothing’s strange about flooding in Brazil’s summer rainy season, the intensity of this year’s storms is above the norm, dropping “absurd,” to quote Fabiana Weykamp of Climatempo, amounts of rainfall in some places.

AFRICA – Floodwaters have also hit several countries across southern Africa.

What’s to Blame?

We could start with the fact that we are now experiencing an unusual and especially strong La Niña, the phase of the El Niño-Southern Oscillation in which cooler-than-normal sea surface temperatures form along the equator in the Pacific Ocean affecting weather worldwide.

Why unusual? Because normally, the shift from El Niño to La Niña occurs more gradually. We began 2010 in the grips of an El Niño, then flipped to La Niña in just two months last summer, finishing the year with one of the strongest La Niñas ever recorded.

So is the La Niña to blame for all the rain? It’s true that La Niña events typically bring more rainfall to Australia, a situation that has most assuredly come to pass.

But it’s also true that La Niñas are supposed to bring dry conditions to California — and that hasn’t yet happened, not by a long shot. All the December rains in Southern California made for the wettest holiday season in L.A. in more than a century.

So something else is clearly going on. That something may very well be the Arctic Oscillation, which once again is strongly negative — a state which, in addition to bringing rain to California this year, also produces warm temperatures in the Arctic and frigid, snowy conditions to the eastern United States and Europe.

If this is the case, one has to wonder what’s going to happen in California now. More wet weather driven by a negative Arctic Oscillation or dry conditions driven by the La Niña?

And one might also wonder why we are seeing these intense swings in weather patterns. Some have speculated that global warming is to blame; there are others, no doubt, who disagree. Regardless, you got to admit, despite all our grand achievements, we are all pretty helpless when Mother Nature decides to let go.

Source: National Climatic Data Center, NOAA

filed under: Africa, Australia, climate change, drought, El Nino-Southern Oscillation, faculty, food, global warming, La Nina, rainfall, Statistically Speaking, weather
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2 Comments

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  1. Lou Grinzo
    Jan 18, 2011

    Check Jeff Masters’ blog (http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=1727) for a brief list of SST’s near recent flooding events. Sounds like an artifact of the quick El Nino/La Nina flip.

    • Bill Chameides
      Feb 7, 2011

      Lou: Yes, one possible explanation for floods in some locations is the change to La Nina conditions. But it is wrong to use “artifact” in this context, which implies that the phenomenon is not real — it most certainly is real.

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