Atmosphere Journal Entry

Weak El Niño Forms in Pacific (September 21, 2009)

A weak El Niño has formed in the Pacific Ocean, the first to appear since 2007. El Niño is a climate event marked by warmer than normal ocean temperatures in the central and eastern Pacific Ocean along the equator. It's likely to have an affect on weather patterns around the globe at least through the spring of 2010, according to the World Meteorological Organization.

It's hard to predict exactly how El Niño will affect global weather, since other atmospheric and ocean current factors come into play. In the past, El Niño has been linked to heavy rains and floods along the Pacific coast of South America, especially in Peru and Ecuador. Eastern Africa also tends to be wetter than normal. By contrast, northern Australia and the Western Pacific region are often drier than normal in El Niño years.

In the United States, the Northeast and upper Midwest usually have milder winters. California, the Southwest, and states surrounding the Gulf of Mexico have wetter weather. The Pacific Northwest usually gets drier and milder winter weather. Because it can increase wind shear over the Atlantic Ocean that rips storms apart, El Niño could signal a milder hurricane season.

Earlier this year, a mild La Niña (El Niño's "little sister") influenced global weather patterns. La Niña is marked by cooler Pacific Ocean temperatures and often brings the opposite effects of El Niño.