A groundbreaking study led by scientists from the U.S. National Science Foundation National Center for Atmospheric Research (NSF NCAR) reveals that increased atmospheric moisture over Africa could alter critical weather patterns, affecting the formation of Atlantic hurricanes. The research, published in the Journal of Advances in Modelling Earth Systems, sheds light on the intricate relationship between regional moisture and hurricane development.

The Birthplace of Hurricanes

Africa serves as the birthplace for weather systems that later evolve into powerful Atlantic hurricanes. While previous research has explored the impact of warmer ocean water and a moister atmosphere on hurricane intensity and rainfall, the specific role of atmospheric moisture in hurricane formation remained elusive—until now.

Weaker African Easterly Waves

The study focused on African easterly waves, which act as the primary precursors or "seeds" for Atlantic hurricanes. Researchers found that increased moisture in the environment led to weaker and slower-moving waves. These disturbances struggled to pair with intense and deep convection, hindering their growth. As a result, hurricane seed formation was delayed by the time the waves reached eastern Atlantic waters.

Unraveling the Role of Moisture

NSF NCAR scientist and lead author Kelly Núñez Ocasio emphasised the importance of understanding moisture’s precise role in cyclogenesis. With the development of new modelling capabilities, Núñez Ocasio delved into the impact of moisture on hurricane seeds, providing valuable insights for future research.

Next-Generation Modelling

Cyclogenesis—the complex process behind hurricane and tropical cyclone formation—requires a comprehensive approach. Most climate models offer only a limited view of localized weather events, making it challenging to study individual ingredients like moisture. To address this, the research team turned to the Model for Prediction Across Scales (MPAS), which allows both global and local weather modelling.

Using MPAS, the team simulated a moisture-driven African easterly wave that became Hurricane Helene in 2006. By adjusting moisture levels, they observed changes in convection and thunderstorms. Surprisingly, increased moisture shifted the energy source of tropical cyclone seeds northward, weakening the waves and leaving them energy starved.

Future Implications

While this study provides critical insights, further research is needed to determine whether weaker seeds lead to less intense tropical cyclones and hurricanes. As climate change continues to alter atmospheric conditions, understanding these dynamics becomes increasingly vital for disaster preparedness and mitigation.

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