April 2019 Climate Forecast Discussion for May-Jul through Aug-Oct
The SST forecast shows weak to moderate El Nino conditions (approximately 1.0ºC for the Nino3.4 SST index) for May-Jul, declining to weak conditions (0.5 - 1.0ºC) from Jun-Aug through Aug-Oct. Much of the extratropical North Atlantic and North Pacific SSTs, as well as the SSTs in mainly the central and western Indian Ocean and parts of the middle and high latitude south Pacific, are predicted to be above-average during most of the four forecast seasons. A relatively small area of below-average SST is predicted in the very high latitudes south or southwest of South America for all four forecast seasons. A positive Indian Ocean Dipole is predicted for all four forecast seasons, most strongly in May-Jul and Jun-Aug. Slightly above-average SST is predicted for the north and south tropical Atlantic for May-Jul and Jun-Aug, returning to average for Jul-Sep and Aug-Oct.
A tilt of the odds toward below-normal precipitation is forecast for the Philippines and central Chile during May-Jul, and for Indonesia and the Caribbean for all four forecast periods of May-Jul through Aug-Oct. Enhanced probabilities for below-normal precipitation are also predicted for eastern Australia for Jun-Aug and Jul-Sep, Central America for Jun-Aug through Aug-Oct, and part of northern South America for Jul-Sep and Aug-Oct. Weakly enhanced chances for above-normal precipitation are forecast for parts of southeastern South America for all four forecast seasons, and in part of northern Asia for Aug-Oct. Enhanced probabilities for above-normal are also predicted for interior eastern equatorial Africa for May-Jul through Jul-Sep, and for central-southwest Asia, south-central Asia, part of northern South America, and part of western North America for May-Jul and Jun-Aug.
Enhanced probabilities for above-normal temperature are predicted for Greenland, and varying parts of Australia, Asia, Africa, North America, South America and Europe from May-Jul through Aug-Oct. Tilts of the odds are strongest for all four forecast seasons in Greenland, west Asia and/or eastern Europe and north-central Asia, and for May-Jul in northern Australia and northwestern North America. For most of the forecast seasons, the above-normal signal is weak or absent in the southeastern U.S., parts of China, southern Australia and the southern quarter of South America. Enhanced probabilities for below-normal temperature do not appear in this set of forecasts. An enhanced likelihood for near-normal temperature is predicted for parts of northern coastal South America for all four forecast seasons, and in southeast Asia and northwestern Indonesia for May-Jul and central Africa for Jun-Aug.
