May 2017 Climate Forecast Discussion

May 2017 Climate Forecast Discussion for Jun-Aug through Sep-Nov

The SST forecast shows development of weak El Niño conditions by Jun-Aug, growing slightly to reach weak/moderate strength by the fourth forecast season of Sep-Nov. A positive Indian Ocean Dipole exists throughout the four forecast seasons, becoming slightly 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 parts of northern and central South America during Jun-Aug and Jul-Sep, settling to mainly northern South America during Aug-Oct and Sep-Nov. An enhanced likelihood for below-normal is predicted for Indonesia and eastern Australia during Jun-Aug, becoming stronger during the last three forecast periods. A tilt of the odds toward below normal is also forecast for central Africa for the final season of Sep-Nov.

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 northern North America during the last two seasons. Probabilities for above-normal are strongest in Greenland during all four forecast seasons, expanding to northern North America during the third and especially fourth season. The tendency toward above-normal temperature becomes progressively stronger between the first and fourth forecast season, covering much of Asia, northern Africa, Australia and central and northern South America by Sep-Nov.