Climate report: La Niña is expected to develop slowly and weakly in the coming months. What will be its impact on the rainy season?

Arab Weather - Specialists at the Arab Weather Regional Center said, after following up on the latest computer modeling outputs for the deviation of the temperature of water bodies from the averages, that the eastern tropical region of the Pacific Ocean has recently witnessed a negative anomaly in the temperature of surface waters, as the water temperature is cooler than its averages by an amount ranging between one and a half to two degrees, with expectations of the weak La Nina phenomenon growing in the coming months. In contrast, the temperature of the waters of the western part of the tropical Pacific Ocean continues to be higher than the averages.

La Niña is expected to develop slowly and weakly in the coming months.

According to the latest reports from NOAA, climate model outputs indicate a 60% chance of a weak La Niña developing in the tropical Pacific Ocean over the coming months. The phenomenon is expected to continue until January-March 2025, potentially impacting global weather patterns.

Data also indicate that sea surface temperatures in the eastern and central Pacific Oceans have been near or below average since the beginning of 2024. While the western Pacific Ocean has experienced above-average temperatures, reflecting a neutral condition (mild climate conditions).

NOAA expects negative surface temperature anomalies to persist in the eastern Pacific, while above-average temperatures have prevailed in the western Pacific and Indian Oceans over the past weeks. These weather patterns are expected to continue to influence weather conditions in many regions around the world.

The La Niña phenomenon is statistically associated with periods of rain interruption and the occurrence of cold waves at various times in the Middle East.

Forecasters at the Arab Weather Center indicated that the La Niña phenomenon is statistically linked to periods of rain interruption in the Middle East region, and to the recurrence of cold waves, as it is linked to the intensification of the Siberian high's influence on the Arabian Peninsula and the Levant during the winter. The La Niña phenomenon often affects the Arab region with a lack of rain in the Levant, but the opposite happens in the Maghreb regions, where rain increases and temperatures drop below average, and the chance of floods and torrents increases in the Maghreb regions, while the chance of drought increases in the Levant regions due to the shape of the weather systems that allow the Siberian high to expand.

During a La Niña, cold waters in the Pacific Ocean push the jet stream northward, causing drought in the southern United States and heavy rains and flooding in the Pacific Northwest and Canada. During a La Niña year, winter temperatures are warmer than usual in the south and colder than usual in the north. La Niña can also lead to a more intense and severe hurricane season than usual, as we have seen recently.

For those interested and specialists: What is the La Niña phenomenon?

La Niña is a weather pattern in the tropical Pacific Ocean where sea surface temperatures are lower than normal. La Niña develops when the trade winds (which blow from east to west along the equator) change and become stronger than normal, primarily because of a rise in atmospheric pressure over the eastern Pacific Ocean and a fall in atmospheric pressure over the western Pacific Ocean. When the trade winds, which blow from east to west, become stronger, warm surface water moves more toward the western Pacific Ocean. This constant pushing causes cold water to be exposed from the depths and rise to the surface in areas near South America. As the cold water continues to flow, the average sea surface temperature becomes lower than normal.

Scientifically, La Niña affects the distribution of heat energy around the Earth, with cold water in the eastern Pacific Ocean reducing evaporation, limiting cloud and rain formation in some areas around the world, while warm water concentrations in the west promote rain formation in places like Indonesia and Australia.

Looking at the latest analysis of ocean temperature anomalies, we can see a lower-than-normal temperature anomaly in the central and eastern regions of the tropical Pacific Ocean, which is similar to a wave caused by strong easterly trade winds pushing water westward, creating eddies on the ocean surface.

La Niña phenomenon greatly affects global weather patterns

La Niña greatly affects global weather, causing variations in weather patterns. This phenomenon increases the chances of rain and flooding in areas such as Australia, Southeast Asia, and northeastern Brazil. In contrast, it brings dry weather to the United States, particularly the southwest, and parts of South America. During La Niña seasons, flooding and heavy rains increase in parts of Asia and Australia, and droughts and forest fires increase in areas that suffer from low rainfall, such as the southwestern United States and some areas in South America, and it becomes colder in Canada and parts of Europe in the northern United States.

According to the National Oceanic and Atmospheric Administration (NOAA), La Niña occurs every few years, lasting for several months, and in some cases, for more than a year. La Niña can intensify and last for up to two years, and its severity varies depending on how cold the waters in the Pacific Ocean are.

(Specialists have pointed out that La Niña affects the pattern of air currents and global weather in multiple ways, which may lead to changes in temperatures and precipitation in different regions of the world, but it cannot be said with certainty that its effects will be inevitable in terms of their impact on the world’s climate, as all likely effects are the result of statistical processing of the years in which this phenomenon occurred, with the need to emphasize that these climate cycles are only an integral part of giant patterns that drive global weather systems.)

The greatest knowledge remains with God Almighty.