October 2018 Climate Forecast Discussion for Nov-Jan 2018 through Feb-Apr 2019
The SST forecast shows moderate El Nino conditions (>1.0C and <1.5C for the Nino3.4 SST index) developing by the initial Nov-Jan season, continuing through Feb-Apr. Much of the subtropical and extratropical North Atlantic and North Pacific SSTs, as well as the SSTs in much of the mid- to high-latitude Southern Hemisphere, are predicted to be above-average during all four forecast seasons. Exceptions are noted in the very high latitudes north/northeast of North America and south of South America, where below-average SST is predicted for all four forecast seasons. Slightly below-average SST is also predicted in the southeast tropical Pacific for the Nov-Jan and Dec-Feb seasons. A positive Indian Ocean Dipole is predicted for all four forecast seasons. Above-average SST is predicted for the north and south tropical Atlantic for Nov-Jan and Dec-Feb, and for the north tropical Atlantic all four seasons.
A tilt of the odds toward below-normal precipitation is forecast for Indonesia, the Philippines and northern and western Australia for all four forecast seasons (Nov-Jan through Feb-Apr). Enhanced probabilities for below-normal precipitation are also predicted for parts of northern South America and southwestern Africa for Dec-Feb through Feb-Apr, parts of coastal southeast Asia for Jan-Mar and Feb-Apr, and southern Greenland in Nov-Jan. 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 varying parts of Asia for all four forecast seasons. Above-normal is also favored for the northern portion of eastern equatorial Africa for Nov-Jan.
Enhanced probabilities for above-normal temperature are predicted for most of Greenland, and varying parts of Australia, Asia, Africa, North America and South America, and non-western Europe from Nov-Jan through Feb-Apr. For most of the forecast seasons, the above-normal signal is weak or absent in the southern one-third of South America, the southeastern U.S., south-central Africa and part of central Asia. Enhanced probabilities for below-normal temperature are very scant, and appear weakly in part of central or northeast Asia in Dec-Feb. An enhanced likelihood for near-normal temperature is predicted for various small parts of northern South America, south-central or western Africa, and western Indonesia in all four forecast seasons.
