May 2018 Climate Forecast Discussion for June-August through September-November
The SST forecast shows neutral ENSO conditions for the initial Jun-Aug and Jul-Sep seasons, then transitioning to warmer conditions, reaching a borderline or weak El Nino level by Sep-Nov. The remnants of the ended La Nina are expected to persist weakly just south of the equator during the Jun-Aug and Jul-Sep seasons. Much of the subtropical and extratropical North Atlantic, and especially North Pacific SST, as well as the SST in much of the mid-latitude Southern Hemisphere, is predicted to be above average during all four forecast seasons. An exception is noted in the high latitude southeast Pacific waters in the Southern Hemisphere, which are predicted to be below average during all four forecast seasons. A near-neutral to very slightly positive Indian Ocean Dipole is predicted for Jun-Aug through Sep-Nov.
Enhanced probabilities for below-normal precipitation are predicted for much of Central America and Caribbean islands for June-Aug through Aug-Oct, and quite strongly for part of northern South America for Aug-Oct and Sep-Nov. A tilt of the odds toward below-normal is also predicted for Indonesia, parts of eastern Australia, and central Chile for Jun-Aug through Sep-Nov, and for south-central or southeastern South America from Jun-Aug through Aug-Oct. Enhanced chances for above-normal precipitation are forecast for parts of the African Sahel or Gulf of Guinea for Jul-Sep and Aug-Oct, for parts of central/northern India and Nepal for Jun-Aug, and for northeastern Asia for all four forecast seasons.
Enhanced probabilities for above-normal temperature are predicted for Greenland, and for varying parts of Asia, Europe, northern Africa, North America and South America from Jun-Aug through Sep-Nov. The tilts toward above-normal are strongest in Greenland, central Asia, eastern Europe, and central or northern North America for most of the four forecast seasons, Tilts of the odds toward below-normal temperature are very scant for the four forecast periods, but appear in part of northern North America and part of northern and south-central Asia in Aug-Oct and Sep-Nov. An enhanced likelihood for near-normal temperature is predicted for small parts of northeastern South America and central and northwestern Africa mainly for Jun-Aug and Jul-Sep.
