Above-average sea surface temperatures, a natural cycle of increased hurricane activity, and a fading La Nina have influenced the 2011 Atlantic hurricane outlook.

The tornado outbreak across the southern United States in late April 2011 was deadly, devastating, and record breaking. NOAA's "CSI" team is investigating the possible connections between global warming, natural climate patterns, and tornadoes.

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.

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.

The early wet season of 2010 was typical of La Niña, with rainfall in December 2010 between 200 and 400 percent above normal in much of Queensland, according to the Australian Bureau of Meteorology.

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