In anticipation of the likely El Nino conditions, experts are advising decision makers and the general public to develop preparedness and response actions to manage the potential impacts associated with the El Nino phenomenon.
Over the past few days, different parts of the country have experienced heavy rainfall, which has led to flooding and landslides in some areas.
Authorities have explained that Sea Surface Temperatures (SSTs) in the tropical Pacific are surpassing El Nino thresholds.
Climate models indicate that this trend is expected to continue until the end of 2023.
During El Nino events in Uganda, heavy rainfall is often associated with the phenomenon, according to expert.
“It should be noted that El Nino alone does not guarantee rainfall, but rather it modulates weather patterns that result in increased rainfall over Uganda during the September, October, November, and December (SOND) rainfall season,” said Bob Alex Ogwang, the Acting Director of the Uganda National Meteorological Authority (UNMA).
However, Ogwang clarified that the rainfall amounts associated with El Nino can vary significantly from one event to another.
For example, in 1987, there was an El Niño year, but it did not result in heavy rainfall.
Similarly, in 2015, the El Niño index was higher than in 1997, but the rainfall was not as severe as it was in 1997.
The occurrence of heavy rainfall and flooding during the October to December 1997 period in Uganda was attributed to both El Nino and a positive Indian Ocean Dipole (IOD) occurring simultaneously.
“The impacts of El Niño on the East African region are influenced by the Indian Ocean Dipole. The interaction between the Indian Ocean and Pacific Ocean affects rainfall amounts and patterns in Uganda,” Ogwang explained.
El Nino refers to the large-scale ocean-atmosphere climate interaction linked to periodic warming of Sea Surface Temperatures (SSTs) across the central and east-central Equatorial Pacific Ocean.
Experts state that El Niño events occur irregularly at intervals of 2-7 years, with an average frequency of about once every 3-4 years.
This is part of the El Nino Southern Oscillation (ENSO) cycle, which includes phases of warming (El Niño), cooling (La Niña), and neutral conditions.
El Niño directly affects rainfall distribution in the tropics and can have a strong influence on weather across Uganda during the September to December rainfall season.
Its presence can significantly impact weather patterns across Uganda and other parts of the world for an extended period of time.
The World Meteorological Organization (WMO) and other Global Climate Centers report that El Niño has been evolving since March 2023, following a long multi-year La Niña, and is likely to persist until early 2024.
Sea Surface Temperatures observed at the end of July 2023 indicate above-average SSTs across the central and eastern Pacific Ocean.
Ogwang stated that the development of El Niño is highly likely, with a greater than 90% chance of it continuing throughout the September to December 2023 rainfall season.
However, the Pacific Ocean and the atmosphere are yet to become fully coupled, as has been the case in previous El Nino events.
Ogwang emphasised that authorities will continue to monitor the evolution of El Niño and provide regular updates and advisories to the public.
“UNMA is currently developing the September, October, November, and December (SOND) 2023 Seasonal Rainfall Outlook, which will be issued in due course,” he said
