Weather Vane. Deficient August for north-west, central India

If July rainfall has been below normal by a wider-than-expected margin of 16 per cent, August too has not been drastically different. This trend is in line with model forecasts.

The week ending August 12 left behind a deficit of 31 per cent while the week that followed (ending August 19) saw the shortfall being reduced to 10 per cent, thanks to monsoon getting briefly ‘active’ over south peninsula and ‘vigorous’ over east and north-east India. During the latter phase, a rain surplus visited Tamil Nadu and Lakshadweep in the South; Assam, Meghalaya, Arunachal Pradesh and sub-Himalayan West Bengal in east and north-east; and West and East Rajasthan in the north-west.  

The forecast issued by the India Meteorological Department, Pune-based Indian Institute of Tropical Meteorology and the Hyderabad-based facility of Indian Council of Agricultural Research, valid for the next two weeks, is as follows: The extreme north and south peninsula as well as most parts of central and north-west India will likely witness deficient to scanty rainfall during the week ending August 27. As a result, the country as a whole will be deficient during the week.

Deficient to scanty rainfall is also the forecast for major parts of north-west India, central India and south peninsula for the subsequent week that runs until September 3. Rainfall will be normal to excess over Met subdivisions mainly over east and north-east India during the week ending September 3.

As per this update, during the last fortnight, normal or above normal rainfall was reported from the Met subdivisions of East Rajasthan, West Madhya Pradesh and Coastal Andhra Pradesh.  Normal or above normal rainfall occurred in either of the last two weeks in Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Haryana, Delhi, West Rajasthan, East Uttar Pradesh, East Madhya Pradesh, Chhattisgarh, Marathawada, Vidarbha, Bihar, Sub-Himalayan West Bengal, Sikkim, Arunachal Pradesh, Assam, Meghalaya, Telangana, Rayalaseema, Coastal Karnataka, South Interior Karnataka, Kerala and Tamil Nadu.

Below-normal rainfall occurred in the Met subdivisions of Punjab, West Uttar Pradesh, Jharkhand, Gangetic West Bengal, Odisha, Gujarat State, Konkan, Goa, Madhya Maharashtra, Nagaland, Manipur, Mizoram, Tripura and North Interior Karnataka.

The outlook for the next fortnight suggests that normal or above normal rainfall would be largely confined to Arunachal Pradesh, Assam, Meghalaya, Nagaland, Manipur, Mizoram, Tripura, West Bengal, Sikkim, Bihar, Odisha and Jharkhand.  

Normal or above normal is forecast in either of the next two weeks in Jammu and Kashmir, Himachal Pradesh, East Uttar Pradesh, Chhattisgarh, Coastal Andhra Pradesh, Rayalaseema, Telangana, Tamil Nadu and Kerala.

Below-normal rainfall would be the likely trend for Uttarakhand, Punjab, Haryana, Delhi, West Uttar Pradesh, Rajasthan, Gujarat State, Maharashtra, Madhya Pradesh and Karnataka. 

A fresh rain-generating low-pressure area is forecast to evolve early this week but models have failed to arrive at a consensus over its capacity to gain traction over the mainland.

This is because they are not too sure if the ‘low’ would be able to hold on its own free from the disruptive influence of a typhoon pair raging concurrently in the north-west Pacific.  

Even though crops experienced moisture stress over regions such as Gujarat and Madhya Maharashtra up to third week of July and over Telangana up to first week of August due to deficient rainfall during earlier weeks, the situation improved due to good rainfall during the last three weeks.

But in Marathwada, North Interior Karnataka and Rayalaseema, crops are still experiencing moisture stress due to deficient rainfall during the last few weeks even though there is some improvement of the situation in Marathawada due to rainfall during last week. On the other hand, there are reports of floods in Assam during end of July and in Gangetic West Bengal and Manipur during the first week of August due to heavy to very heavy rainfall.