From the Siberian to the jet stream... weather factors have weakened the rainy season. What's the connection to climate change?

Arab Weather - The Meteorological Department issued a statistical report indicating that the current 2024/2025 rainy season is the weakest since the 1978/1979 season, and the general trend of rainy seasons indicates a decrease in the average seasonal rainfall in the Kingdom by about 0.6 mm per rainy season.

Several reasons have made the rainy season weak at the moment in Jordan.

Arab Weather experts explained that the primary reason for the weak rainy season was that the shape of the weather systems in the northern hemisphere caused cold air masses to rush into the Kingdom and the eastern Mediterranean along a dry axis. This means that the cold air masses did not cross large bodies of water and instead followed a continental path, accompanied by the expansion of the Siberian high pressure system, which resulted in the cold and frost waves that occurred in late November and mid-December.

The second reason for the weak rainy season is a significant shift in the polar jet stream toward southern Europe, the central Mediterranean, and North Africa. This resulted in the concentration of low-pressure systems in those regions, accompanied by heavy rains and snowfall. In turn, these systems pushed strong high-pressure systems toward the Kingdom and the eastern Mediterranean.

In addition to the aforementioned reasons, the weak rainy season is due to the development of a climate cycle in the Pacific Ocean, specifically off the coast of Peru, called "La Niña." This cycle refers to a cooling of the waters of the tropical Pacific Ocean and a drop in water temperature below average. This has been reflected in the region by the strengthening of high-pressure systems that act as a barrier to the advance of low-pressure systems.

Is climate change the reason for the weak rainy season this year?

In answer to this question, we can delve deeper into the matter. The atmosphere and oceans follow natural cycles that span 5 to 30 years, producing specific weather patterns in the Northern Hemisphere. At the same time, we are witnessing a phenomenon of global warming that has worsened since the beginning of the Industrial Revolution in 1840. During this period, humans have significantly increased the emission of greenhouse gases that trap heat in the atmosphere and radiate it back to Earth, resulting in a temperature rise of 1-2 degrees Celsius.

Arab Weather explains that although global warming has been present for many years, the weather changes we are witnessing now are largely linked to the temperature of the ocean surface and the distribution of air masses around us. However, it cannot be said with certainty that climate change is the primary cause of the weak rainy season, especially since the Kingdom's climate fluctuates in terms of rainfall during the winter seasons. It also cannot be overlooked that global warming has contributed to an increase in extreme weather conditions in the region, God willing. Referring to historical data, we find that the weak rainy season we are experiencing is not unusual or exceptional; it has occurred in the past and will recur, God willing, in the future.

And God knows best.