IMD Tracks Bay of Bengal Low and Himalayan Disturbance
Why in News?
- The India Meteorological Department's update of 12 November 2026 expects a low-pressure area over the southeastern Bay of Bengal around 13 November, moving northwest and becoming better organised by 14 November, and it could intensify into a depression by 15 November, Down To Earth reported.
- A western disturbance and an upper-air cyclonic circulation over Kashmir will bring heavy rain to Jammu and Kashmir and Ladakh, with snow at higher elevations and some hail.
- Adirampattinam in Tamil Nadu recorded 39°C on 11 November, the country's highest maximum, while Mandi in Himachal Pradesh recorded a minimum of 8.6°C.
Key Terminologies
- Low-Pressure Area and Depression
- Stages in the development of a tropical system over the sea. A depression is the stage with sustained winds of about 31 to 49 km/h, and it can strengthen into a cyclonic storm if conditions allow.
- Western Disturbance
- A system of low pressure from the Mediterranean region that brings winter rain and snow to northwest India and the Himalayas, and sometimes hail.
- Upper-Air Cyclonic Circulation
- A circulation of winds in the upper atmosphere. Over Kashmir it works with the western disturbance to bring heavy rain and snow.
- Andaman and Nicobar Islands
- Islands in the Bay of Bengal where the report forecasts isolated heavy rain, thunderstorms and gusts up to 60 km/h, with rough seas.
- Adirampattinam and Mandi
- Places that recorded extremes: Adirampattinam in Tamil Nadu had the highest maximum, 39°C, and Mandi in Himachal Pradesh a minimum of 8.6°C.
Key Issues
- Bay of Bengal System: A low-pressure area is expected over the southeastern Bay of Bengal around 13 November, to move northwest and be better organised by 14 November, and could become a depression by 15 November. Its track will decide rain and wind in coastal and island areas.
- Western Himalayas: A western disturbance and an upper-air cyclonic circulation over Kashmir will bring heavy rain to Jammu and Kashmir and Ladakh, with snow at higher elevations, hail in places and gusts of 40 to 50 km/h. Himachal Pradesh may see thunderstorms.
- South India: Thunderstorms and lightning are forecast for Kerala, Mahe, Tamil Nadu, Puducherry and Karaikal. The report gave no rainfall amounts.
- Islands: The Andaman and Nicobar Islands may see isolated heavy rain, thunderstorms, gusts up to 60 km/h and rough seas.
- Temperatures: Delhi-NCR had a maximum of about 29°C and a minimum of about 16°C on 12 November with persistent air pollution. Night temperatures were more than 5°C below normal in parts of eastern Madhya Pradesh and south interior Karnataka.
Key Implications
Positive/Pros/Merits
- Early Notice: A forecast of stages from a low to a depression gives states time to prepare for rain and winds.
- Water and Snow: Rain and snow in the Himalayas help water supply and hill agriculture such as apples.
- Cooler Air: Cooler conditions in the north may help clear some pollution, though the report notes air quality remains poor.
- Better Tracking: Regular IMD updates help sailors, fishers and island authorities.
Negative/Cons/Demerits
- Cyclone Risk: A depression in the Bay of Bengal could strengthen, adding to the two storms that hit Andhra Pradesh in the last two weeks.
- Hill Hazards: Heavy rain, hail and snow can cause landslides, damage to crops and disrupt roads.
- Island Dangers: Rough seas and strong gusts are a risk for fishing and ships near the Andaman and Nicobar Islands.
- Forecast Uncertainty: The track and strength of the Bay system were not yet clear.
Key Initiatives
- India Meteorological Department: It issued the 12 November 2026 update on the Bay of Bengal system and the western disturbance.
- State Disaster Management Authorities: They use IMD alerts to prepare for rain, snow and storms.
- Fishermen and Ports: They receive advisories for the Bay of Bengal and the island region.
- Hill States: Jammu and Kashmir, Ladakh and Himachal Pradesh prepare for snow and landslide risk.
The Down To Earth update gave no daily dates for the Himalayan weather and no rainfall amounts for south India. It did not forecast rain for Andhra Pradesh. The earlier report of 11 November discussed the cyclone risk in more detail.
Director's Perspective
Way Forward
- Learn the stages of a tropical system: low-pressure area, depression, cyclonic storm.
- Know what a western disturbance is and why it brings winter rain and snow.
- Remember that IMD issues the forecasts and alerts.
- Link Himalayan snow and rain to water supply and landslides.
- In answers, note that the Bay of Bengal system and the western disturbance act together on weather in November.
The IMD update shows two systems at work in mid-November: a developing low over the Bay of Bengal that could become a depression by 15 November, and a western disturbance bringing rain, snow and hail to the Himalayas. Both bring benefits for water and risks of damage, and the Bay system's track is still uncertain. In a Mains answer, explain how such systems form and are classified, link them to the post-monsoon season, and conclude that early warning and local preparedness reduce losses.
GS Relevance
Frequently Asked Questions
What did IMD forecast for the Bay of Bengal on 12 November 2026?
IMD expects a low-pressure area over the southeastern Bay of Bengal around 13 November, moving northwest and becoming better organised by 14 November, and it could intensify into a depression by 15 November, Down To Earth reported.
What is a western disturbance?
A western disturbance is a system of low pressure from the Mediterranean region that brings winter rain and snow to northwest India and the Himalayas, and sometimes hail. On 12 November 2026 one, with an upper-air cyclonic circulation over Kashmir, was forecast to bring heavy rain and snow to Jammu and Kashmir and Ladakh.
Which place recorded the highest maximum temperature in India on 11 November 2026?
Adirampattinam in Tamil Nadu recorded 39°C on 11 November 2026, the country's highest maximum, while Mandi in Himachal Pradesh recorded a minimum of 8.6°C, according to the IMD update reported by Down To Earth.
PYQ Practice — Statement Analysis
1 A depression is a stage in the development of a tropical cyclone.
IMD said a Bay of Bengal low could intensify into a depression by 15 November 2026.
2 A western disturbance originates in the Bay of Bengal.
It is a system from the Mediterranean region that brings winter rain and snow.
3 IMD is the agency that issues weather forecasts and alerts in India.
It issued the 12 November 2026 update.