Heavy rain regime seen migrating back to north India with monsoon trough

The well-marked low-pressure area over the Bay of Bengal, off the North Andhra Pradesh-South Odisha coasts, persisted on Wednesday morning. India Meteorological Department (IMD) had put it under watch for further intensification into a monsoon depression, the first this year, as per its outlook on Tuesday evening. 

The monsoon has delivered a rain surplus of five per cent for the country, with only East and North-East India running a deficit of -24 per cent. Central India, which began with a deficit and sustained until early July, finds itself in above-normal category with a 14 per cent surplus. South Peninsula has salvaged its position to -1 per cent, although Kerala continues to show a -32 per cent deficit, followed by Rayalaseema at -25 per cent. North-West India holds on to its 35 per cent surplus, secured from early June.

Weak monsoon phase?

Morning update from IMD on Wednesday said the rain-driving well-marked ‘low’ may move slowly across the North Andhra Pradesh-South Odisha coasts, but didn’t stress on further intensification. Meanwhile, the western end of the monsoon trough over the plains of North India may shift northwards during the next two to three days, signalling an important phase of the season. 

The monsoon trough passed through Bikaner, Kota, Guna, Jabalpur, Pendra Road, Jharsuguda and the centre of the well-marked ‘low’ pressure area, before dipping into the East-Central Bay. Global model suggests the rainfall regime will move entirely towards North India, and progressively towards the foothills of the Himalayas from early August, likely signalling a ‘break monsoon’ phase.

Inevitable recess

A ‘break’ is inevitable in August after the monsoon vents its fury over land variously during June and July, as it has done this time too. This is the time when it strikes a pause to ‘breathe in’ before ‘breathing out’ to become active again and return to its normal phase. How long the break phase lasts will be crucial in August, normally the second rainiest month after July. 

Monsoon shuts out over large parts of the country during a break phase, except over the foothills of the Himalayas, parts of North-East India and the East Coast, especially Tamil Nadu. The European Centre for Medium-Range Weather Forecasts suspects the monsoon may enter this mode as early as July-end into the first week of August and likely beyond.

Heavy rain today

The IMD sees isolated very heavy rain for Himachal Pradesh and Uttarakhand on Wednesday and Friday; and over Haryana and West Uttar Pradesh on Wednesday. Isolated extremely heavy rain may lash Konkan, Goa and the ghat areas of Madhya Maharashtra on Wednesday. 

Over South India, the IMD has forecast isolated very heavy rain over Karnataka on Wednesday and Thursday as the well-marked ‘low’ powers its way along the East Coast. Isolated extremely heavy rainfall also is likely over Telangana during these two days, and over Coastal Andhra Pradesh, Coastal and South Interior Karnataka and Rayalaseema on Wednesday.