Dynamic Models: For shorter lead times (2-4 months), all the dynamic forecasts for the tropical Pacific agree in calling for a continued decline of the current El Niño. For longer lead times (6-9 months), the models fall into two categories. (i) The NCEP coupled GCM and the JPL/UCLA hybrid coupled model predict a relatively slow decline of the warm anomalies giving weak warm conditions for the boreal winter of 1998-99. (ii) The COLA coupled GCM and BMRC intermediate coupled model forecast a stronger cooling trend with La Niña conditions developing for the winter of 1998-99.

Statistical Models: For short lead times, the statistical models agree with each other and the dynamic models in forecasting a continued weakening of the current El Niño. Similar to the dynamic models, for longer lead times the statistical models fall into two categories. The singular spectral analysis-maximum entropy method predicts that the warm anomalies will persist through the winter of 1998-99, whereas the linear inverse model, the neural network model, the analogue model and the consolidated forecast all indicate that a La Niña will develop during the winter of 1998-99. There are two statistical forecasts for the tropical Atlantic in this Bulletin. The linear inverse model predicts continued warming in the tropical Atlantic peaking in the winter of 1998-99. The canonical correlation analysis also gives continually developing warm anomalies in the tropical Atlantic through January 1999.

Dynamic Models: The NCEP tier two AGCM forecast for North American temperatures is calling for relatively warm conditions throughout Canada and the eastern two thirds of the U.S. to persist through July 1998. During the middle summer early fall the model forecasts near normal temperatures for most of Canada and somewhat cool conditions for the south eastern third of the U.S. For precipitation during early summer, the model forecasts a relatively dry southern U.S. A wet central Pacific coast is predicted for the early summer. During late summer and fall relatively wet conditions are forecast for the southeastern U.S. There are two AGCM forecasts for South America in this issue of the Bulletin. The CPTEC/COLA AGCM predicts relatively dry conditions in Amazonia and Nordeste for March-May 1998. The forecast also calls for a relatively wet spring in south Brazil. The UKMO AGCM forecast for the Amazon basin agrees with the CPTEC/COLA forecast, whereas over the Nordest the UKMO model gives relatively wet conditions.

Statistical Models: Linear regression temperature forecasts for U.S. during April-June 1998 indicate relatively warm conditions will prevail in the west and in Florida with below normal temperatures in the Mississippi Valley. The precipitation forecast calls for above normal rainfall in the Pacific northwest during April-June 1998. The April-June 1998 canonical correlation analysis forecast for Canada is for relatively cold conditions to prevail. The precipitation forecast calls for relatively wet conditions in western and far eastern Canada and relatively dry conditions in central Canada. The canonical correlation analysis forecast for the Pacific islands during April-June 1998 indicates relatively wet conditions along the equator and dry conditions just to the north and south of the equator. The linear regression temperature forecast for central England during July and August 1998 is for weak positive anomalies. The July to September 1998 canonical correlation analysis forecast for the Sahel is below normal rainfall in western and eastern portions and near normal conditions in the central Sahel. Statistical forecasts for the Nordest region of Brazil use both Atlantic and Pacific SSTA. Conditions in the Pacific tend favor relatively dry conditions, whereas conditions in the Atlantic favor relatively wet conditions. The April-July 1998 northern Uruguay empirical forecast calls for relatively wet conditions.