Second wettest Sept in 27 years bridges monsoon deficit

PUNENEW DELHI: Above-normal rainfall this month, which turned out to be the second wettest September in the past 27 years, has almost bridged the deficit of the monsoon season with the cumulative rainfall showing the gap to be narrowed down from 9% on August 31 to merely 1% on Wednesday, indicating the four-month season may finally be logged as ‘near normal’ monsoon.
The India Meteorological Department (IMD) had on June 1 predicted that the southwest monsoon seasonal (June 1-September 30) rainfall over the country as a whole is most likely to be ‘normal’ at 101% of the long period average (LPA) with model error of /-4%. The LPA of the season rainfall over the country as a whole for the period 1961-2010 is 88 cm. The season has already recorded nearly 87 cm of cumulative rainfall even as the monsoon has not yet started retreating.
“The IMD had forecast ‘above normal’ rain in September. There were consecutive low pressure systems, and depressions over the Bay of Bengal this month. Thus, the monsoon was active during the month. Our latest prediction for the entire monsoon 2021 was that it may end up being on the lower side of normal, and thus far, the departure from the long period average for June-September 2021 is just -1%. The rain in September made a significant contribution to the season, and overall we had a near-normal monsoon this year,” IMD director general Mrutyunjay Mohapatra told TOI.
As far as rainfall in September is concerned, the month has recorded 34% excess rains at 223 mm (September 1-29) against a monthly normal of 166.6 mm. The rain recorded so far during September in the country is the second best figure for rains during the month since 1994.
“September turned out to be just the opposite of August… Several low pressure systems formed over the Bay of Bengal, some of which had re-emerged from the northwest Pacific, which too had not happened in August,” said D S Pai, scientist and head of climate research and services, IMD, Pune. Rainfall, linked to cyclonic circulation, in Gujarat, Maharashtra, Gangetic West Bengal, Bihar, Odisha and Jharkhand is likely to completely end the deficit in next 24 hours, which will see intense rainfall activities due to the remnants of the cyclonic storm ‘Gulab’ that had hit the eastern coast last Sunday.
The remnants moving towards the western coast, observed as a well-marked ‘low pressure area’ over south Gujarat region & adjoining Gulf of Khambhat on Wednesday morning, is very likely to emerge into northeast Arabian Sea & intensify into a ‘depression’ by Wednesday morning. The Met department on Wednesday said the cyclonic system is then very likely to move further west-north-westwards and intensify into a cyclonic storm, named ‘Shaheen’, during the subsequent 24 hours (by October 1). Thereafter, it is likely to continue to move west-north-westwards towards Pakistan’s Makran coasts, moving away from the Indian coasts.
IMD’s data on cumulative rainfall over the four homogenous regions shows the maximum deficit of rainfall as on Wednesday in east & north-east India (-12%) followed by north-west India (-4%). On the other hand, the south peninsula region shows a surplus of 11% whereas central India shows a surplus of 3%.