NOAA’s National Weather Service announced today that El Nino has developed in the tropical Pacific, and issued an El Nino Advisory. El Nino, the warm phase of the El Nino Southern Oscillation (ENSO), is predicted to intensify to a moderate or strong level this fall. Forecasters predict a 63% chance of sea surface temperatures exceeding 2.0°C in the Nino-monitored region of the Pacific. If this threshold is surpassed, NOAA considers the event a “very strong” El Nino.