Since Lake Tahoe lies at the southern edge of the typical Pacific Northwest patterns, local weather is likely to be a mix of wet and dry.

La Niña episodes are marked by stronger-than-normal easterly trade winds and below-normal sea surface temperatures in the eastern tropical Pacific Ocean. These changes in ocean temperature and atmospheric circulation have worldwide implications for weather patterns. Ocean surface temperatures are shown on the NASA image below. The red arrow points at Tahoe-Truckee Region.



This image shows the temperature anomaly for the top millimeter of the Pacific Ocean's surface-the skin temperature. In this image, taken January 14, 2008, temperatures are compared to the long-term average measured by a series of sensors that flew on NOAA Pathfinder satellites from 1985 to 1997.

A strong band of blue (cool) water appears along the Equator, fanning out near North and South America. Patches of orange to red (warm) water conditions appear north and south of this strong blue band. As of January 2008, the U.S. National Oceanic and Atmospheric Administration (NOAA) predicted that La Niña conditions would continue until spring, with a possible weakening in February 2008.

Cool ocean temperatures can impede cloud growth, leading to reduced rainfall from South America to Indonesia. In the continental United States, La Niña affects the jet stream, which in turn affects weather. Because La Niña conditions can persist for years, such adverse weather conditions can continue. In short, continued La Niña conditions were expected to prolong the droughts in the American Southeast and Southwest.

La Niña conditions first appeared in February 2007 and they strengthened in October and November. La Niña conditions often peak in January, as they appeared to be doing in January 2008.