3TIER, a speciality provider of weather information to renewable energy companies, used observations and computer modelling to assess the impact of the El Niño-Southern Oscillation (ENSO). Fewer areas had higher-than-average speeds.

“It is fair to say that only a few areas known for their concentrated wind resources outperformed their average yearly wind speeds,” 3TIER founder and chief executive Kenneth Westrick says in a statement.

The ENSO occurs over the tropical Pacific Ocean every two to seven years and has marked effects on weather in North and South America, and elsewhere in the world. Seattle, for example, had its warmest January on record, for which the ENSO pattern gets some credit, according to local meteorologists.

The pattern includes warming ocean surface temperatures in the eastern Pacific and high pressure over the western Pacific. Another pattern known as La Niña is characterized by the opposite conditions.

The National Weather Service Climate Prediction Center on Thursday issued an update on the current trend: “El Niño is expected to continue at least into the Northern Hemisphere spring 2010.”

Expected impacts in the coming months may include “drier-than-average conditions over Indonesia”; above-average precipitation and below-average temperatures in the southern tier of the US and below-average rain and snow in the Pacific Northwest and Ohio Valley, as well as other northern tier states.

3TIER says winds on the West Coast, for example, intensified and climbed above the 1969-2008 average in the second half of 2009. (See map of fourth-quarter variance from average below.) Other areas experiencing above-average winds include the Southwest, southern Great Plains and coastal regions north of the Gulf of Mexico, says Jim McCaa, 3TIER’s director of advanced applications.

Lower-than-average speeds occurred in the north central Plains and the Northeast.

Fourth-quarter 2009 wind speed variance from long-term average.

3TIER says project owners, financiers and grid operators integrating large amounts of variable wind energy should account for large-scale patterns such as ENSO – which Westrick says can be forecast “with a considerable degree of certainty” – in making production and revenue estimates, and planning system operations.

"There is a tendency to concentrate the development of wind farms in areas that have high average wind speeds and assume that production will be consistent over the long-term,” McCaa says in a statement. “However, areas with very good wind resources are not immune from a number of long-term oscillations that have a significant impact on production from year to year.”