Nairobi, Kenya — The torrential rains and deadly floods that have hit Kenya since March have been some of the most catastrophic in the country in recent years.
At least 169 people have died due to heavy rain and more than 91 are missing, according to the latest government figures.
In the most tragic development, at least 48 people died on Monday after water broke through a blocked river tunnel under a railway bridge in southwestern Kenya, causing a flash flood. The rain has displaced more than 100,000 people and damaged roads and other infrastructure.
The devastating rains are the result of a combination of factors, including the country’s seasonal weather patterns, human-caused climate change and natural weather phenomena.
This is how they combined to create the deadly flood.
WHAT IS THE “LONG RAINS” SEASON IN KENYA?
Kenya and some other parts of East Africa have two main rainy periods: the “long rains” season, from March to May, and the “short rains” season, from October to December.
The “long rains” season is when most of the country’s average annual precipitation occurs. It is often characterized by torrential rains and sometimes lasts until June.
In its forecast for this year’s “long rains” season, the Kenya Meteorological Department predicted above-average rainfall in many parts of the country, with occasional thunderstorms in some. It also warned of flash flooding, mudslides, mudslides and other impacts.
Last year’s “short rains” season was characterized by severe storms in many parts of the country, especially in November. Lamu, Mombasa and Garissa counties received almost three times the long-term average rainfall, according to the meteorological department.
WHY IS THE RAIN SO INTENSE THIS TIME?
The frequency, patterns and intensity of rainfall in Kenya are influenced by natural weather systems such as the Indian Ocean Dipole.
The Indian Ocean Dipole is an oscillation of sea surface temperatures that makes the western Indian Ocean warmer than average and then colder than the average eastern Indian Ocean. It has positive, neutral and negative phases.
The positive phase causes heavy rainfall in areas west of the Indian Ocean, such as Kenya, and droughts in Indonesia and Australia.
While many people have linked the current floods to the natural El Niño weather phenomenon, research shows that the weather event has little influence on rainfall in East Africa during the “long rains” season, said Joyce Kimutai, a research associate at the Imperial College London.
El Niño is ocean warming over the Pacific Ocean, which changes storm paths and can cause heavy rain in some parts of the world and drought in others.
But in the case of Kenya, the positive Indian Ocean dipole and climate change are very likely to explain the continuous rains causing flooding, he said.
Warmer oceans caused by a warmer atmosphere increase evaporation and air that retains more moisture can produce heavier precipitation.
In an analysis in December last year, Kimutai and his colleagues at World Weather Attribution, a group of scientists looking at whether climate change influenced extreme weather, found that human-caused climate change had made the snow season last year’s “short rains” in Kenya and other parts of East Africa up to twice as intense.
WHEN WILL THE “LONG RAINS” END?
In recent years it has become difficult to predict the long-term climate in Kenya, as the onset and duration of the dry and wet seasons increasingly change.
The Kenya Meteorological Department expects the “long rainy” season to continue until June.
In its latest seven-day weather forecast, released on Monday, the department said it expects rain to continue in several parts of the country, with heavy downpours likely in six regions, as well as flooding in low-lying areas and landslides. on steep slopes.
__
The Associated Press’ climate and environmental coverage receives financial support from multiple private foundations. AP is solely responsible for all content. Find AP’s standards for working with philanthropic organizations, a list of supporters and funded coverage areas at AP.org.