El Nino has knocked down the core monsoon month of August, beyond recovery. The hard-hitting impact will list the month as ‘driest’ since 1901. August 2023 is heading for an overall deficiency of about 35% rainfall. August 1899 continued to be an all-time driest, since the reliable records were held, with effect from 1871. August 1899 was sapless with biggest-ever shortfall of 40.4% rainfall.
Break monsoon conditions remained pervasive for nearly 24 days in the month. With the dismal performance of August, the danger of monsoon 2023 being listed as a ‘drought’ year looms large. The month of September holds the key for ‘make’ or ‘break’. This month has a modest normal of 167.9mm rainfall but is considered the most volatile to swing the fortunes.
Intra-seasonal variation of monsoon activity remains an inbuilt characteristic. Strong conditions followed by lull or mild activity is a common sequence for the southwest monsoon. However, a prolonged wet spell in July, trailed by sleepy August, remains an exception. The month of August started with above-normal seasonal rainfall of 105% of the long period average (LPA) and is slated to end with a large deficit of 90% of LPA. The month of August has a normal 254.9mm rainfall and is expected to have a mammoth shortfall of about 90mm rainfall.
The start of September comes with a silver lining after the upset of August. There is partial recovery likely during the first 10 days of the month. A cyclonic circulation has formed over the Northeast Bay of Bengal (BoB). It is likely to be established during the next 48 hours and get relocated at the top end of BoB. Under its influence, a low-pressure area may form over the same region in the subsequent 48 hours. This weather system largely holds the fate of the monsoon during September.
The month of September needs to excel to save the monsoon from the scare of drought. Seasonal rainfall deficiency, in excess of 10% of LPA gets rated as ‘drought’ or ‘deficient’. Pan India's seasonal rainfall will start with a shortfall of 10%. Courtesy low-pressure area, any further fall will get arrested, albeit temporarily. El Nino impact will continue without dilution and may tighten grip during the 2nd half of September. This last month of the season assumes critical importance and will decide the grade of the monsoon. If the month receives its normal rainfall or even a modest shortfall of about 10%, the season can avert the scare of ‘drought’. Any deficiency, in excess of 15% rainfall will push it closer to yet another El Nino-driven ‘drought’.