Oct 2022 Climate Forecast Discussion for Nov-Jan through Feb-Apr 2023
Note: Note: The IRI seasonal forecasts of precipitation and temperature issued this month are based on an objective calibration procedure that combines the NCEP-CFSv2, CanSIPS-IC3, COLA-RSMAS-CCSM4, and GFDL-SPEAR, and NASA-GEOSS2S models. The climatological base period for normal is 1991-2020.
In September 2022, the equatorial sea surface temperatures (SSTs) in the central-eastern tropical Pacific Ocean remained cooler than normal, exhibiting persistent La Niña conditions (NINO3.4 index value in September 2022 was -1.09). According to the early-October CPC ENSO forecast, La Niña is likely to continue until boreal winter 2022-23 with 75% probabilities, which would be the first triple-dip event of the 21st century; however, a transition to ENSO-neutral is likely during Feb-Apr 2023 (54% chance). The prolonged La Niña SST pattern in the tropical Pacific does impact the associated seasonal climate forecast. In addition, a weak negative Indian Ocean Dipole Mode is forecasted for Nov-Jan and Dec-Feb 2023 (overlapping 3-month forecast seasons) before transitioning to a neutral state. The tropical Atlantic Ocean exhibits slightly warm SST anomalies.
The precipitation forecast for Nov-Jan 2023 season shows moderately enhanced probabilities of below-normal precipitation over the southern parts of the US and most of Mexico, the Middle East and central southwest Asia, parts of southeastern Africa, northeast Madagascar, northeast China including Korea and Japan, over and around Uruguay and southern Chile. During Dec-Feb, Jan-Mar, and Feb-Apr 2023, moderately enhanced probabilities of below-normal precipitation persist over southwest US and northern Mexico regions. Increased probabilities of wetter conditions are forecast over the Maritime Continent, much of Australia, over northern South America, northwest US regions adjoining Canada, South Africa, over parts of southeast Asia, again generally decreasing in strength through the forecast period. Many, though not all, of these precipitation patterns are consistent with historical La Niña teleconnections.
For temperature, enhanced probabilities of above-normal temperatures are forecasted over much of East Asia, central southwest Asia, large parts of northern African continent, most eastern United States, and southern South America during the forecast period. Enhanced probabilities of above-normal and near-normal temperature probabilities are forecasted over the Maritime Continent region during the entire forecast period. Moderately enhanced probabilities of below-normal temperatures are forecasted for much of Alaska and Canada (particularly in Jan-Mar 2023), South Africa, over parts of southeast Asia, and much of Australia, during the forecast period. During Dec-Feb, Jan-Mar, and Feb-Apr 2023 forecast shows weak probabilities of near- or slightly below- normal temperatures over most of northern and central parts of South America, while near- or slightly above- normal temperatures over the Sahel and tropical southern Africa regions.
