Dynamic Models: For the tropical Pacific, the dynamic forecasts agree that there will be at least moderate La Niña conditions in the next 1-2 seasons. There is some disagreement among the models as to the strength and timing of the cooling in the eastern Pacific. The NCEP model forecasts a relatively weak La Niña for the boreal winter of 1998-99, whereas both COLA forecasts call for considerably stronger La Niña conditions to peak in the boreal spring of 1999. The NCEP and COLA models return to near normal conditions in the summer and fall of 1999. The SIO/MPI model predicts relatively large cold SSTA during winter in the central Pacific with relatively weak anomalies along the east coast of South America and a fairly rapid return to near normal in the summer and fall of 1999. Both versions of the LDEO model predict modest La Niña conditions that persist throughout 1999 and return to normal by early 2000. The BMRC model calls for a strong cooling trend to begin in the next 2-3 months with cooling continuing until September 1999. The BMRC forecast returns to normal by early 2000.

Statistical Models: The linear Inverse model predicts moderate La Niña conditions for the winter of 1998-99 decaying rapidly though the summer of 1999. The neural network model prediction also calls for modest La Niña conditions to peak around the first two months of 1999. The constructed analogue prediction is for relatively strong La Niña conditions peaking in late 1998 and early 1999. The CLIPPER and the NCEP Markov model forecasts also call for a moderate to strong cold event for late 1998 and early 1999. The singular spectrum analysis-maximum entropy method forecasts very weak La Niña or near normal conditions for the winter of 1998-99. The linear inverse model predicts an end to the warm conditions in the Caribbean and the north tropical Atlantic in early 1999.

Dynamic Models: The NCEP tier two AGCM forecast predicts no significant temperature anomalies over North America during winter 1998-99. During spring anomalous warmth is predicted over the central and southeastern U.S. The precipitation forecast calls for relatively dry conditions in much of the mid-Atlantic and southern parts of the U.S. to prevail through spring 1999. ECPC seasonal forecast using persisted SSTA and NCEP's regional spectral model indicate relatively wet conditions to prevail in much of the Pacific northwest through January 1999. The CPTEC South American AGCM DJF98-99 rainfall forecast calls for dry conditions in northern Peru, Ecuador, Columbia and western Brazil and relatively wet conditions in central southeastern Brazil. During the March-May 1999 rainy season the CPTEC forecast indicates weak positive precipitation anomalies in the north of northeast Brazil.

Statistical Models: Linear regression temperature forecasts for the U.S. during JFM99 indicate relatively warm conditions will prevail in the far west and extreme south. The CCA forecast for Canada during MAM99 calls for relatively cold temperatures in central and eastern Canada and warm temperatures in the west, particularly to the north. The CCA Canada precipitation forecast for MAM99 calls for dry conditions in south central and northeast Canada and wet conditions in the far eastern part of the country. The CCA forecast for the Pacific islands indicate that Hawaii and the U.S. affiliated stations will have above normal rainfall this boreal winter. Locations close to the equator from 170E and eastward are forecast to be dry. The CCA forecast for South Africa, Botswana and Nambia calls for above normal rainfall in the region for JFM99. Empirical forecasts over northeast Brazil indicate relative wet conditions for the January-June 1999 period. Empirical forecasts for 1999 also call for 7 hurricanes for the Atlantic and 15 tropical cyclones for the Australian region.