August 2023 Climate Forecast Discussion
Aug 2023 Climate Forecast Discussion for the period Sep-Nov 2023 through Dec-Feb 2024
In July 2023, sea surface temperatures (SSTs) in the central-eastern equatorial Pacific Ocean were well above the El Niño threshold (the NINO3.4 index value in July 2023 was +1.07 °C). Weekly-averaged SST anomalies in the NINO3.4 region have warmed further and reached +1.2 °C during the week centered on 09 Aug 2023. According to the early-Aug CPC ENSO forecast, the tropical Pacific is experiencing El Niño conditions and an El Niño Advisory remained in place. Both observations and model forecasts indicate the presence of warm SST anomalies in the Atlantic Ocean, and a positive Indian Ocean Dipole during the forecast period.
Strongly or moderately enhanced probabilities for below-normal precipitation are predicted for most of the northern half of South America, the Maritime Continent, and Australia during the forecast period. Weakly enhanced probabilities of below-normal precipitation are also forecasted for parts of southern and central Africa. A strong tilt of the odds toward above-normal precipitation is predicted over and around the Greater Horn of Africa, the Middle East, and central Asia during the forecast period. Gradually increasing probabilities for above-normal precipitation are also forecasted over and around Uruguay, southern and southeast US, and northern and eastern China during the forecast period. Enhanced probabilities of above-normal precipitation are also forecasted over western and northwestern Africa during Sep-Nov, persisting until Nov-Jan over southern parts of West Africa. Many, though not all, of these precipitation patterns are consistent with historical El Niño as well as positive Indian Ocean Dipole events.
Regarding temperature, strongly enhanced probabilities for above-normal temperature are forecasted across most land areas throughout the forecast period. Enhanced probabilities for below-normal temperature do appear locally during the forecast period, notable over southeast Madagascar. These become more widespread during Oct-Dec over the eastern United States, Colombia, parts of Europe, eastern Africa, Madagascar, and central Asia, but are largely limited to the Oct-Dec season.
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