Flood Journal Entry
La Niña Blamed for Floods (March 17, 2008)
Color-coded satellite map shows rainfall totals over a recent four-week period in northern South America. Areas in orange got over 500 mm of rain. Brown shows areas with at least 300 mm of rain while yellow represents over 200 mm. NASA.
Meteorologists say La Niña, the weather pattern known as El Niño's little sister, gets some of the blame for deadly floods that have raged across northern and central South America since February.
The floods killed at least fifty-two people in Bolivia, Peru, and Ecuador and forced thousands of people to flee to higher ground.
La Niña is marked by cooler than normal ocean temperatures in the central and eastern Pacific Ocean along the equator. It's the opposite of El Niño, which brings warmer ocean temperatures to the Pacific Ocean.
Like it's more famous "brother," La Niña affects weather around the globe, often in ways opposite of El Niño. It's been linked to heavier rain in parts of South America as well as in Indonesia and Australia. This year, La Niña was blamed for nasty winter weather in China.
In North America, the Pacific Northwest usually gets more rain while parts of Canada get heavier snow in La Niña years. The southern United States is usually drier than normal. La Niña also changes the flow of the jet stream, the weather "superhighway" high in the atmosphere over North America. This increases Atlantic hurricane activity by reducing wind shear that tears storms apart.
The current La Niña is expected to stick around for at least another month or two.
