December 2018 Climate Forecast Discussion for Jan-Mar 2019 through Apr-June 2019
The SST forecast shows moderate El Nino conditions (>1.0ºC and <1.5ºC for the Nino3.4 SST index) during Jan-Mar and Feb-Apr, becoming weak (>0.5ºC and <1.0ºC) for Mar-May and Apr-Jun. Much of the extratropical North Atlantic and North Pacific SSTs, as well as the SSTs in much of the tropical and southern subtropical Indian Ocean and part of the high latitude south Pacific, are predicted to be above-average during most of the four forecast seasons. Below-average SST is predicted only in small areas in the very high latitudes just south of Greenland and south of South America for Jan-Mar and Feb-Apr for the latter, and all four seasons for the former. A positive Indian Ocean Dipole is predicted for all four forecast seasons, especially Mar-May and Apr-Jun. Above-average SST is predicted for the north and south tropical Atlantic for all four forecast seasons, but mostly for only the north during Mar-May and Apr-Jun.
A tilt of the odds toward below-normal precipitation is forecast for the Philippines, part of Indonesia, variable parts of northern South America, southern Africa and parts of Australia for most or all four forecast seasons (Jan-Mar b through Apr-Jun). Enhanced probabilities for below-normal precipitation are also predicted for parts of coastal southeast Asia for Mar-May and Apr-Jun. Enhanced chances for above-normal precipitation are forecast for part of southeastern South America, parts of the southern U.S. and/or northern Mexico, and weakly for varying parts of Asia for most or all of the four forecast seasons.
Enhanced probabilities for above-normal temperature are predicted for Greenland, and varying parts of Australia, Asia, Africa, North America, South America and Europe from Jan-Mar through Apr-Jun. For most of the forecast seasons, the above-normal signal is weak or absent in the southern one-third of South America, southeastern U.S. and western Europe. However, most of Europe is predicted to have above-normal temperature during Apr-Jun. Enhanced probabilities for below-normal temperature are very scant, and appear weakly in part of northeastern Europe in Mar-May. An enhanced likelihood for near-normal temperature is predicted for various parts of northern South America, tropical Africa, and Indonesia in most or all of the four forecast seasons.
