Abstract

One of the consequences of the new NOAA definition of El Niño is the identification of a number of boreal autumns and winters as El Niño seasons that are not conventionally so identified. In these periods SST anomalies are concentrated significantly more toward the International Dateline than usual. We show here that the seasonal weather anomalies typically associated with these additional “Dateline El Niño” seasons are different in useful respects over much of the world, and suggest that it is useful to treat these as different types of “El Niño” for purposes of seasonal weather forecasting.