Weather Vane. July may end with rain deficit

Monsoon rains for the country as a whole were deficient by 6 per cent as on July 24, but this hides more telling statistics. For July, precipitation has been 26 per cent below normal. July is traditionally the rainiest of the four months of the season.

This is only slightly better than the end of the last week (32 per cent deficit). Large tracts of central and southern India remained dry with 39 per cent and 44 per cent below-normal rainfall.

Among the four main geographical areas, only north-west India finds itself in a comfortable position with a surplus rainfall of 6 per cent. This has been made possible by a biased run by the monsoon in the past few weeks. It has been piloted by low-pressure areas moving west across the landscape from the Bay of Bengal — from Gangetic West Bengal-Odisha to Chhattisgarh, Madhya Pradesh and Rajasthan to Gujarat. These ‘lows’ occasionally interacted with incoming western disturbances from the other side of the international border in Pakistan.

These types of interactive rains conjured up by monsoon ‘lows’ and western disturbances have traditionally produced the maximum rainfall for north-west India. So, this is in line with the known monsoon pattern for this region. But the rest of the country — which is practically the entire peninsula and adjoining parts of central India — has been saddled with rain deficits carried over from the last week of June and into early July.

The deficit as on date (June 1 to July 24) is most prominent in the southern peninsula (13 per cent), followed by central India (10 per cent) and east and north-east India (5 per cent).

For August, the prognosis is not very bright, according to two international weather models which have come out with their latest projections.

Both the Tokyo-based Applications Laboratory of Japanese national forecaster Jamstec and the APEC Climate Centre based in Busan, South Korea, suspect that below-normal conditions would be the most likely outcome for most parts of India during August. The only exception will be east and north-east India which would likely see excess rainfall thanks largely due to the proximity to warm Bay of Bengal waters.

An extended-range weather forecast put out back home by the India Met Department along with the Indian Institute of Tropical Meteorology and the Indian Council of Agricultural Research says practically the same thing. It notes that Gujarat, Madhya Maharashtra, Marathwada, Vidarbha, north interior Karnataka, Telangana and Rayalaseema witnessed deficient rainfall during last few weeks.

Its outlook for the next two weeks is: rainfall will likely be normal to above-normal over central and north-west India with pockets of deficient rainfall over south peninsula and east and north-east India during the week July 24 to 30.

For the week that follows (July 31 to August 6), the main rainfall belt will continue to stay over north-west India while it will be just about normal over central India but below normal rainfall over the south peninsula.

The dry spell in the south peninsula could gradually spread to central and north-west India during the rest of the month, if the Japanese and South Korean forecasts are any indication.