A heavy monsoon has been walloping parts of moisture-stressed East India and the South Peninsula with very heavy to extremely heavy rain over the past few days, even as numerical model projections indicated that the activity may spill into the first week of September, the fourth and last month of the season.
Monsoon trough retreats
This has come about at a time when the all-important monsoon trough, which has been active over Central India so far, has, for the first time this season, retreated to the foothills of the Himalayas. This is normally identified best with ‘break-monsoon’ conditions during which the monsoon activity shuts out briefly across most places of the country, except along the Himalayan foothills, the North-East and the East Coast. The North-East has received deficient rainfall during the last few years since the monsoon trough chose to stay away and kept itself busy over adjoining East, Central India, and West India, in a pattern becoming familiar in recent years. The trough may have retreated to the foothills, but it has not robbed other parts of the country their due thanks to the presence of a constellation of cyclonic circulations and troughs.
Troughs and circulations
The India Meteorological Department (IMD) pointed to a cyclonic circulation hovering over North Jharkhand and over South Coastal Andhra Pradesh. A trough extended from around the Andaman and Nicobar Islands to South Coastal Andhra Pradesh and adjoining North Tamil Nadu. These ensured that the moisture collected from the Bay was propagated over the South Peninsula. The monsoon trough over the Himalayan foothills brought some showers to the plains of North-West India.
Rain for East, North-East
The IMD said the 24 hours ending on Monday morning saw rain or thundershowers break out over most of Arunachal Pradesh, the plains of West Bengal, Sikkim, Jharkhand, Uttarakhand, East Madhya Pradesh, Chhattisgarh, Kerala, and South Interior Karnataka across the South Peninsula and East India. Many places in Assam, Meghalaya, Bihar, East Uttar Pradesh, Himachal Pradesh, Jammu, Kashmir, Ladakh, Rayalaseema, Tamil Nadu, Puducherry, Lakshadweep, and Coastal and North Interior Karnataka received rain or thundershowers. Extremely heavy rainfall lashed parts of South Interior Karnataka while it was very heavy over Arunachal Pradesh, Uttarakhand, Bihar, Odisha, Jharkhand, hills of West Bengal, Tamil Nadu, and Kerala; and heavy over East Uttar Pradesh, East Madhya Pradesh, Chhattisgarh, Assam, Coastal Karnataka, North Interior Karnataka, plains of West Bengal, Rayalaseema, Telangana, and Coastal Andhra Pradesh.
Readying for withdrawal
Flash floods and landslides were reported in Kerala on Sunday night. At least five members of a family were killed in Idukki district when their house was washed away. A three-day outlook by IMD from Saturday spoke about the possibility of fairly widespread to widespread light to moderate rainfall activity over the South Peninsular India, the West Coast, Central, North-East, and East India. It will be isolated to scattered light to moderate over the remaining parts of the country except Rajasthan and Gujarat, which will stay dry as the monsoon prepares to withdraw from extreme North-West India.