Conditions in northwest Pacific affected monsoon
The rainfall deficiency of five per cent of the long-period average (LPA) of southwest monsoon season was largely due to below par rainfall in the second half of the season during August and September, the India Meteorological Department (IMD) said in its end of the season report. During the second half of monsoon, northwest India and Central India saw rainfall deficiency of 35 per cent of LPA and 21 per cent of LPA.
According to IMD’s analysis, there was above normal activity of low pressure systems over the northwest Pacific during the second half of monsoon, resulting in poor rains during the same period in India.
“The below normal rainfall over the central and northwest India during second half of the season was also caused by the above normal convective activity over southern hemispheric equatorial trough,” the IMD’s report said. It added, thus, the Bay of Bengal branch of southwest monsoon got deflected towards southeast Asia owing to strengthening of west Pacific systems.
The influence of these systems manifested in lesser low-pressure systems. This year, 11 low pressure areas formed in the first half of the season with three of them intensifying into depressions, the report said. It added, on the other hand, during the second half of the season, only three low-pressure systems formed in the Indian monsoon region with none of them intensifying into depression.
“The total number of lowpressure system days during the season had been only 39 as against the normal of 58,” the IMD’s report said.
Rajasthan and Gujarat witnessed extreme heavy rainfall—FILE