India’s southwest monsoon has ended on an optimistic note, with 8% more rain than anticipated. Reassuringly, the rainfall forecast by the India Meteorological Department (IMD), particularly since July, was accurate. Monsoon clouds continue to prevail over the country but given the centrality of rainfall to the Indian economy, focus has already shifted to the ‘other monsoon’, the northeast monsoon. It is named so because of the direction in which the winds exit from the land mass into the sea. Following the withdrawal of the southwest monsoon in mid-October, the northeast monsoon is characterised by a reversal of winds that brings rain to parts of coastal Andhra Pradesh, Tamil Nadu, Kerala, and parts of southern Karnataka. For Tamil Nadu, the northeast monsoon is the main source of rainfall. The northeast monsoon brings in only about 11% of India’s annual rainfall.
The IMD has forecast that this year’s post-monsoon rainfall is likely to be ‘above normal’ or about 12% over the historical average. Because of its limited spread and quantity, the northeast monsoon does not get as much attention as the southwest monsoon. However, it significantly affects the productivity of rice and maize in Tamil Nadu and Andhra Pradesh. Records show that in years of deficiency, there was a considerable decrease in agricultural production in the region. The northeast monsoon rainfall, averaged over the five subdivisions where it is predominant, has a variation of almost 25%, exceeding that of the southwest monsoon rainfall (10%). This translates into years of massive deluge followed by dry spells. In 2015, Chennai experienced a deluge during the northeast monsoon, resulting in significant loss of life and property. In 2019, the city faced severe water shortage. If this year’s forecast holds, it will be the second consecutive year of a normal northeast monsoon. Expectations are high that a La Nina, or cooling of the equatorial central Pacific, will support this. However, most global models have struggled to forecast the timing of La Nina this year. Thanks to improved forecast systems, the northeast monsoon is less neglected than before. Nevertheless, more focus is needed on modelling its impact regarding urban flooding. Climate change uncertainty makes such prognosis essential, and disaster management agencies in States must develop credible strategies to incorporate these buffers into budgets.
Published – October 05, 2024 12:08 am IST
The other monsoon: On the northeast monsoon
