Long-lead seasonal forecasts - where do we stand?

Abstract

The National Weather Service intends to begin routinely issuing long-lead forecasts of three-month mean US temperature and precipitation by the beginning of 1995. The ability to produce useful forecasts for certain seasons and regions at projection times of up to one year is attributed to advances in data observing and processing, computer capability, and physical understanding-particularly, for tropical ocean-atmospheric phenomena. Because much of the skill of the forecasts comes from anomalies of tropical SST related to ENSO, we highlight here long-lead forecasts of the tropical Pacific SST itself, which have higher skill than the US forecasts that are made largely on their basis. The performance of five ENSO prediction systems is examined: two are dynamical; and two are statistical (canonical correlation analysis and constructed analogs, used at the Climate Prediction Center of NCEP). -from Authors