Near the Earth’s equator, solar heating is intense year round. Converging trade winds and abundant water vapor all combine to produce a persistent belt of daily showers known as the Intertropical Convergence Zone.

As far back as August 2010, NOAA's seasonal climate models predicted that rainfall would be heavier than normal across Indonesia and Southeast Asia in early 2011. The cause? La Niña.

Natural climate phenomena—the North Atlantic Oscillation & La Niña—can explain much of this winter's temperature patterns across North America.

globes showing pressure patterns during positive and negative phases of the Arctic Oscillation

Large-scale shifting of the weight of the atmosphere between mid- and high latitudes creates climate patterns known as the Arctic and North Atlantic Oscillations. These patterns have a big influence on winter weather in the Eastern U.S.

Drought conditions have become more widespread and severe in the Southwest in the first part of 2011.

Most of the southwestern United States is having a very dry winter. The northern parts of Arizona and New Mexico were clipped by a few drenching storms exiting California in December, but dry conditions are more the norm.

Deep snow that fell across the Great Plains and the Northeast in late January and early February is the latest installment in the second very wintry winter in a row for the eastern U.S.

Weather in the Southeast this fall and winter is keeping up with the dry part of the typical La Niña pattern. Precipitation across most of the Southeast was "below" or "much below" normal for October-December.

In early June 2010, NOAA’s Climate Prediction Center reported that the ocean and atmosphere conditions across the Pacific were favorable for the development of a La Niña episode.

Pages