April 2017 Climate Forecast Discussion

April 2017 Climate Forecast Discussion for May-Jul through Aug-Oct

The SST forecast shows El Niño development by Jul-Sep, reaching moderate strength by the fourth and final running forecast season of Aug-Oct. A positive Indian Ocean Dipole exists throughout the four forecast seasons, and becomes somewhat stronger by the fourth season. The tropical Atlantic maintains near to slightly above average SST during all four seasons.

Slightly enhanced probabilities for below-normal precipitation are predicted in far northern South America during May-Jul, progressively strengthening and expanding to include more of northern South America by Jul-Sep, and persisting into Aug-Oct. A similar scenario of strengthening chances for below-normal is predicted for Indonesia beginning in Jun-Aug, and for eastern Australia over the course of all four forecast periods. By Aug-Oct season, the region leaning toward below-normal in eastern Australia expands northward to join Indonesia.

A tendency toward above-normal temperature is predicted in a general manner over much of the globe for all four forecast seasons, with a few exceptions such as a small region in west-central interior North America, straddling the U.S./Canadian border, during the first two seasons. Probabilities for above-normal are strongest in Greenland and northeastern Canada during the second, third and fourth seasons, and in varying parts of Eurasia and South America during the course of the four seasons.