April 2024 Climate Forecast Discussion
Apr 2024 Climate Forecast Discussion for the period May-Jul 2024 through Aug-Oct 2024
**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-CESM1, and GFDL-SPEAR, and NASA-GEOSS2S models. The climatological base period for normal is 1991-2020. The SST anomalies cited below refer to the OISST.v2.1 SST data set.
During March 2024, there was a further decline in the sea surface temperatures (SSTs) within the central-eastern equatorial Pacific Ocean compared to the preceding month, leading to a NINO3.4 anomaly index value of +1.24 °C. The weekly-averaged SST anomalies in the NINO3.4 region were +0.90 °C for the week centered on April 10, 2024. According to the early-April CPC ENSO forecast, both a current El Niño Advisory and a La Niña watch for boreal summer remain in place. The Indian Ocean Dipole (IOD) index is currently positive with the most recent value of +0.95 °C for the week ending March 31, 2024, according to the Australian Bureau of Meteorology. The North Atlantic Ocean continues to exhibit persistent warm SST anomalies. Forecasts indicate that the warming in the North Atlantic Ocean will continue for the next couple of months while the Indian Ocean Dipole is also forecasted to remain in the positive state.
IRI’s seasonal precipitation forecasts issued in April show elevated probabilities of below-normal precipitation in various regions during the forecast period, including Mexico and parts of North America, parts of Brazil, areas in Chile and Argentina, southern Africa. There is a gradual leaning towards above-normal precipitation starting from May-Jul 2024 to the end of the forecast period, over the Central American regions, northern South America, African Sahel region, Greater Horn of Africa, southwestern corner of the Arabian Peninsula, south Asia, the Maritime Continent, central and eastern Australia, and parts of China. Many, while not all of these precipitation patterns align with historical La Niña events, many of them do, which is in line with the forecasted onset of La Niña from the boreal summer of 2024.
Regarding temperature, strongly enhanced probabilities for above-normal temperature are forecasted across most land areas throughout the forecast period. In the northern parts of South America, and southern regions of Australia, the forecast show increased probabilities for below-normal temperatures during May-Jul, and Jun-Aug 2024.