Advancement of Monsoon
Context: The India Meteorological Department (IMD) announced on May 13, 2025, that the southwest monsoon had advanced into parts of the Bay of Bengal and Andaman-Nicobar Islands, marking the beginning of its seasonal progression toward mainland India.
Important Pointers:
► Monsoon has advanced into: South Bay of Bengal, the South Andaman Sea, the Nicobar Islands, and Parts of the North Andaman Sea.
► Announced by: India Meteorological Department (IMD) ► Date: May 13, 2025 ► Kerala Onset Not Yet Declared: • Normal onset date: June 1 • Prediction uses IMD’s custom forecast model
► IMD Forecast for 2025: Above normal monsoon predicted (5% above 87 cm average); Would be the second consecutive year of above-normal rains.
► Current IMD Outlook (as of May 13, 2025): • Rain, thunder, lightning over South Peninsular India and Central India • Heavy to very heavy rainfall in Andhra Pradesh, Karnataka, Kerala, Tamil Nadu, and Northeast India.
Monsoon:
► Type of Monsoon: Seasonal reversal of winds caused by differential heating of land and sea
► Southwest Monsoon Season: June to September
► Branches: • Arabian Sea Branch – hits Kerala coast first • Bay of Bengal Branch – moves towards Northeast India
► Monsoon Onset: • First hits Kerala (~June 1) • Then spreads to the rest of India in ~4-6 weeks
► Monsoon Withdrawal: • Begins from Northwest India around mid-September • Withdraws from the entire country by mid-October
► Rainfall Distribution: • Windward side of Western Ghats: heavy rainfall • Leeward side (rain shadow area): e.g., Vidarbha, Marathwada – less rain • Northeast: heavy rain due to funneling of the Bay of Bengal branch
► Importance: • 70% of India's annual rainfall comes from the SW Monsoon • Crucial for agriculture, groundwater recharge, and the economy