India Meteorological Department (IMD) has said that the monsoon this year will be normal (96-104 per cent of the long-period average, LPA) with the quantum of rainfall likely to be 99 per cent of the LPA with a model error of five per cent.
The IMD outlook came out on Thursday as part of the first long-term forecast for the season, a day after leading private forecaster Skymet Weather declared its long-term outlook assessed the season to be at 98 per cent of the LPA.
IMD assesses the probability of normal rainfall at 40 per cent (33 per cent climatological) and above normal at 15 per cent (16 per cent). Below-normal was at a raised 26 per cent (17 per cent) and deficient rain at 14 per cent (16 per cent). According to Skymet Weather, the probability for normal rainfall is 65 per cent while that of above-normal rainfall is 10 per cent; below normal at 25 per cent; and that of drought, at zero per cent.
Low on ‘excess’ outlook
A defining feature in both was in terms of the poor or nil confidence in assessing the probability of excess rainfall. IMD assessed this probability at 5 per cent and Skymet at zero, compared to the climatological probability of 17 per cent. On the other hand, the probability for deficient rain is high though the Skymet forecast rules out a drought
Climatological probability is based solely on climatological statistics for a region rather than the dynamical implications of current conditions. This is used as a baseline for evaluating the performance of weather and climate forecasts.
The IMD suggests normal to above normal rainfall is likely over many areas of northern parts of Peninsular India and adjoining Central India, along the foothills of the Himalayas and some parts of North-West India. Below normal rainfall is likely over many areas of North-East India, some areas of North-West India and southern parts of the South Peninsula.
Currently, helpful La Nina conditions are prevailing over the Equatorial Pacific region. The latest climate model forecast indicates that La Niña conditions are likely to continue during the monsoon season. Closer home, ‘neutral’ IOD conditions prevail over the Indian Ocean and forecast indicates that these conditions may continue until the beginning of monsoon. Thereafter, enhanced probability for negative IOD condition is predicted.
April 14, 2022