The India Meteorological Department (IMD) recently announced the withdrawal of the southwest monsoon from India, including Mumbai, on October 15. However, this has not led to a complete cessation of rain. Instead, Mumbai has been placed under a yellow alert due to ongoing thunderstorms and moderate showers, attributed to cyclonic circulation systems in the region. This phenomenon has raised questions about the changing weather patterns and their implications for urban environments.
About Cyclonic Circulation
Cyclonic circulation refers to a system of winds that rotate around a low-pressure area. In this case, the IMD identified two key systems: one over North Lakshadweep and another over the Andaman Islands. These systems are responsible for the unusual weather, as they draw moisture from the surrounding areas, creating conditions conducive to thunderstorms. Interestingly, cyclones can impact local climates, with the potential to alter rainfall patterns for extended periods.
The Role of the Northeast Monsoon
As the southwest monsoon recedes, the northeast monsoon begins to take effect, particularly impacting southern and eastern regions of India. However, this year has seen an overlap, with moisture from the northeast monsoon contributing to the ongoing rainfall in Mumbai. This interplay between the two monsoon systems is not uncommon, but the extent of rainfall during this transition period can vary from year to year.
Impact on Mumbai’s Weather
Mumbai has experienced its wettest October in two years, with rainfall figures surpassing monthly averages. The Colaba observatory recorded 113.4 mm of rain, indicating a dramatic shift from the previous year, where only 24.2 mm was logged throughout the entire month. Such fluctuations highlight the increasing unpredictability of weather patterns, possibly linked to broader climatic changes.
Future Weather Predictions
Meteorologists predict that the current cyclonic systems may intensify, leading to increased thunderstorm activity in the coming days. This forecast is crucial for urban planning and disaster management in Mumbai. The IMD has warned that once the thunderstorms subside, a spike in temperatures is expected, a phenomenon often referred to as ‘October Heat’. This term describes the sudden rise in temperatures that can occur following periods of rain, as the atmosphere rapidly warms up.
Temperature Variations and Urban Heat Islands
Currently, temperatures in Mumbai are about 2 °C below normal, with the Colaba station recording 31.3 °C. However, following the expected clear-up, temperatures could soar to around 34-35 °C. This increase can be attributed to the urban heat island effect, where urban areas experience higher temperatures than their rural surroundings due to human activities and infrastructural development. The phenomenon of ‘October Heat’ is a reminder of how urbanisation can exacerbate temperature extremes.
Long-Term Implications
The ongoing changes in weather patterns raise concerns about long-term climatic shifts. Increased instances of unseasonal rainfall can disrupt agricultural cycles, impact water supply, and challenge urban infrastructure. The intensity and frequency of such weather events are often linked to climate change, denoting the need for robust environmental policies and sustainable urban planning.
Conclusion
Mumbai’s recent weather events underscore the complexity of monsoon dynamics and their implications for urban life. As cyclonic systems interact with monsoon patterns, cities must adapt to the realities of fluctuating weather. The importance of monitoring these changes cannot be overstated, as they will influence not only immediate weather conditions but also long-term environmental and social stability.
