News DetailWeak El Nino developing in Tropical Pacifc
Posted At: August 17, 2006 @ 4:12 PM
Posted By: Reed Timmer
Related Categories: General
Based on recent trends in sea surface temperature anomalies (SSTA) and 850 mb wind anomalies (strength of the easterly Trade Winds) in the Tropical Pacific, a weak El Nino event may be initiating. Typically, El Nino events begin in the eastern Pacific, with warm SSTs propagating westerward via the easterly Trade Winds. However, El Nino events can also initiate in the central Pacific, with warm SSTs expanding depending on the presence of certain feedback mechanisms between the ocean and the atmosphere. This current developing El Nino appears to be a combination of both, with warm SSTAs developing in the far eastern and central Tropical Pacific. The positive anomalies in the eastern Pacific are likely a result of weak easterly Trade Winds during the mid summer (see second diagram below), because of decreased upwelling along the South American coast during this time.
The TornadoVideos.net forecast is for the positive anomalies in the eastern Tropical Pacific to expand westward and intensify slightly, with the central Pacific warm SSTAs remaining steady state. Despite a brief strengthening trend in the Trade Winds during late July, it appears that an overall trend towards weaker Trade Winds has occurred throughout the summer, and will likely continue through the fall and early winter. Thus, a moderate El Nino will likely prevail in the Tropical Pacific through at least early winter, resulting in increased precipitation and cloudiness over the southwest and south-central U.S., with a higher probability of Nor' Easter winter storms along the East Coast due to the stronger sub-tropical jet stream. Displayed below are the most recent sea surface temperature anomalies and Trade Wind anomalies (blue=stronger easterly winds, red=weaker easterly winds) centered on August 9, 2006.
Also, the warm SSTAs off the coast of Mexico (top figure) are likely contributing to the very active hurricane season they are experiencing in the eastern Pacific, with Hurricane Hector rapidly gaining strength at the time of this post.
The TornadoVideos.net forecast is for the positive anomalies in the eastern Tropical Pacific to expand westward and intensify slightly, with the central Pacific warm SSTAs remaining steady state. Despite a brief strengthening trend in the Trade Winds during late July, it appears that an overall trend towards weaker Trade Winds has occurred throughout the summer, and will likely continue through the fall and early winter. Thus, a moderate El Nino will likely prevail in the Tropical Pacific through at least early winter, resulting in increased precipitation and cloudiness over the southwest and south-central U.S., with a higher probability of Nor' Easter winter storms along the East Coast due to the stronger sub-tropical jet stream. Displayed below are the most recent sea surface temperature anomalies and Trade Wind anomalies (blue=stronger easterly winds, red=weaker easterly winds) centered on August 9, 2006.
Also, the warm SSTAs off the coast of Mexico (top figure) are likely contributing to the very active hurricane season they are experiencing in the eastern Pacific, with Hurricane Hector rapidly gaining strength at the time of this post.
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