Friday, July 9, 2010

La Niña Is Forming as Expected

Strong effects are more likely to be predictable and that appears to be the case right now. We had a strong El Niño (El Niño-Southern Oscillation) that began in 2009 and ended, as predicted, in April of this year. After a strong El Niño we usually get the opposite phenomenon nicknamed La Niña. I discussed this back in January / February and it appears that this is now occurring.

El Niño is the name given to an oscillatory phenomenon that affects the sea surface temperature in the equatorial eastern Pacific Ocean. During an El Niño the sea surface temperature in the eastern Pacific rises above average, which causes changes in weather on a global scale, but the strong effects mainly occur in the Western Hemisphere. Some regions become drier and some wetter, some places get heavy weather, others get milder weather.

Generally speaking, during an El Niño, Atlantic hurricanes are usually suppressed and North America receives heavy precipitation and a heavy winter, and this did occur in the winter of 2009-2010. Nobody in Washington, DC could remember the last time there was a 3 foot snowfall. In Guatemala, our rainy season was much weaker than normal and we had a long hot dry summer. This occurred in 2009 and into 2010 where we had drought conditions and for 18 months here in Rio Dulce and across most of Guatemala, we only received one sixth the normal amount of rain. As much as 80 percent of the crops were lost in 2009.

Now the pendulum is swinging the other way. Sea surface temperatures in the eastern equatorial Pacific Ocean are plummeting and will probably plunge up to 5 degrees C below normal. We are heading into a La Niña condition, probably a strong one, and that will likely spell troublesome weather for Guatemala and the Caribbean.

In 2009 we got a free-pass on hurricanes. Thanks to El Niño hardly any hurricanes occurred in the Caribbean. A La Niña brings the opposite and we need to expect and prepare for more hurricanes than usual and stronger hurricanes. We have to expect above normal rainfall which brings the hazards of flooding and landslides. And we have to keep closer watch on the weather because during a La Niña, the weather changes more quickly and tropical cyclones can develop much more quickly.

Let's hope the rain comes slow and steady so it refills the aquifers and not in monster downpours that create big runoffs, flooding, destruction of crops, and loss of topsoil.