The northeast monsoon, also known as the 'retreating monsoon,' is a weather phenomenon that occurs in the Indian subcontinent. It is the seasonal wind pattern responsible for bringing rainfall to certain parts of India during the winter months, typically from October to December. Here's a brief explanation of its mechanisms:
Southwest Monsoon Withdrawal: The northeast monsoon follows the southwest monsoon, which brings heavy rainfall to India during the summer months (June to September). As the southwest monsoon weakens and withdraws, it creates a transition period before the onset of the northeast monsoon.
Onset Timing: The onset of the northeast monsoon typically begins in the southern and eastern parts of India in the month of October. However, the exact timing can vary from year to year.
Weak Monsoon: The northeast monsoon is often characterized by weaker rainfall compared to the southwest monsoon. It is sometimes referred to as a "weak" monsoon.
Regional Impact: The northeast monsoon primarily affects the southern and southeastern regions of India, including Tamil Nadu, Kerala, Karnataka, and parts of Andhra Pradesh. These regions receive significant rainfall during this season.
Contribution to Annual Rainfall: While the northeast monsoon contributes to the overall annual rainfall in these regions, it accounts for only around 11% of India's total annual rainfall.
Variability: There is significant year-on-year variability in the performance of the northeast monsoon. In some years, it may bring heavy rainfall and lead to flooding, while in others, it may be weak, causing water shortages.
It's important to note that the northeast monsoon plays a crucial role in the water supply and agriculture of the affected regions. Its onset and performance are closely monitored by meteorological agencies to assess its impact on agriculture and water resources.
In summary, the northeast monsoon is the seasonal reversal of winds that brings winter rainfall to certain parts of India, mainly in the southern and southeastern regions, and its onset typically occurs in October. Its impact can vary significantly from year to year.
India's Monsoon Transition: From Southwest to Northeast"
The southwest monsoon has ended, and the India Meteorological Department (IMD) expects the northeast monsoon to begin within 72 hours. It is anticipated to be relatively weak, known as the 'retreating monsoon.' The southwest monsoon started withdrawing from Rajasthan on September 25, a week later than usual.
Officially, India only considers rainfall from June 1 to September 30 as monsoon. As of September 30, India received 94% of expected monsoon rain, slightly below the IMD's 96% forecast.
'Normal' rainfall (96% to 104% of the average) is expected. The IMD forecasted a 'normal' northeast monsoon for October-December, with 'normal to above-normal' rainfall in north-west India and the southern peninsula.
This forecast is significant for Tamil Nadu, Kerala, Karnataka, and parts of Andhra Pradesh, receiving about 11% of India's annual rainfall.
Yearly variability is common, as seen in Chennai's 2015 floods and a weak 2019 northeast monsoon. The IMD reported two developing low-pressure areas, potential cyclone precursors, in the Arabian Sea and Bay of Bengal, likely becoming 'depressions' by October 21, with further intensification uncertain.
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