"Large-scale weather patterns which occur in various locations around the Earth, from the El Niño-Southern Oscillation (ENSO) in the tropics to the high latitude Arctic Oscillation (AO) play a significant part in controlling the weather on a seasonal time scale. Knowing the condition of these atmospheric oscillations in advance would greatly improve long-range weather predictions. Scientists search for clues in the earth’s surface conditions such as tropical sea surface temperatures and snow cover at higher latitudes. Reliable and accurate weather prediction is vitally important in numerous areas of society, particularly agriculture and water management and weather risks are evaluated by a wide range of businesses, including power distributors who make fewer sales during cool summers and more sales during cold winters. The portion of the U.S. economy sensitive to weather conditions is estimated to be at least $3 trillion."