During December 2011, below-average sea surface temperatures (SST) associated with La Niña continued across the eastern and central equatorial Pacific Ocean.
The weather system La Niña is expected to outlast the winter, government scientists said today, which means the already parched South could stay dry well into the spring.
La Niña is a naturally occurring climate phenomenon located over the tropical Pacific Ocean which results from interactions between the ocean surface and the atmosphere. During La Niña, cooler-than-average Pacific Ocean temperatures influence global weather patterns.
A persistent La Niña dominated climate patterns in late 2010 and early 2011. La Niña was blamed for everything from a record-breaking tornado season to spring flooding. After dying down over the summer, La Niña re-emerged in the tropical Pacific Ocean in late summer 2011 and gradually strengthened as winter began.
A majority of climate models now predict a weak or moderate-strength La Niña to peak between December and February. La Niña should then continue into early spring before dissipating between March and May, according to the U.S. National Oceanic and Atmospheric Administration's (NOAA) Climate Prediction Center.
During January to March 2012, there is an increased chance of above-average temperatures across the south-central and southeastern United States, and below-average temperatures over the western and the northwest-central United States. Also, above-average precipitation is favored across most of the northern states and in the Ohio and Tennessee Valleys, and drier-than-average conditions are more likely across the southern United States.
According to climate and weather experts, 2011's record-breaking number of billion-dollar weather disasters was caused by a combination of factors, including La Niña, local atmospheric patterns and potentially climate change — though the importance of climate in any individual weather scenario is still nearly impossible to put an exact number on.
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