Most of South Asia to record normal or above normal monsoon this year
There is likely to be normal to above normal rainfall over most parts of the South Asian region during the June to September southwest monsoon season, according to a consensus statement released by South Asian Seasonal Climate Outlook Forum (SASCOF) and the Climate Services Users Forum on Wednesday.
Above-normal rainfall is likely over some areas of the northwest, along the foothills of Himalayas and northeast parts of the region, including Nepal and parts of Pakistan, and many areas of the central part of the region in India. However, monsoon rain is most likely to be below normal over many areas over extreme northwest, northeast and some areas over north-eastern parts of the region.
The statement has been developed by all nine National Meteorological and Hydrological Services (NMHSs) of South Asia led by India with Afghanistan, Pakistan, Nepal, Myanmar, Bhutan, Bangladesh, Maldives and Sri Lanka and the process involved expert assessment of the prevailing global climate conditions and forecasts from different climate models from around the world.
“The moderate La Niña conditions that prevailed over the Pacific since July 2020 have weakened to borderline La Niña to ENSO neutral conditions in the month of April 2021. Based on the global climate model forecasts, there is strong consensus among experts that the ENSO neutral conditions are likely to prevail during the southwest monsoon season,” the statement said.
The India Meteorological Department (IMD) had said in its forecast that the monsoon for this year is likely to bring the normal amount of rainfall at 98% of the long period average (LPA) with an error margin of +/- 5%. IMD considers rainfall between 96% to 104% of LPA to be in the “normal” range. In 2020 and 2019 also, the monsoon was above normal at 110% and 109% of LPA.
The SASCOF statement added that during the monsoon season, minimum temperatures are likely to be above normal over most areas of west, northwest, north and north eastern parts of South Asia. The maximum temperatures are likely to be below normal over most of the central parts of South Asia while the maximum temperatures are likely to be above normal over northwest and northern areas of northeast of the region.
ENSO neutral conditions are generally associated with normal southwest monsoon over the region. In a few cases, other regional factors such as Indian Ocean conditions may play a more dominant role in influencing monsoon performance. At present, neutral Indian Ocean Dipole (IOD) conditions are prevailing over the Indian Ocean. The recent forecasts from coupled global models suggest that these neutral IOD conditions are likely to continue during the monsoon season. A few climate models also indicate development of weak negative IOD conditions during the monsoon season which is often associated with a weak monsoon.
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“We issue this consensus statement every year for the region. Like we said before, the region is likely to record normal to above normal rain this year with normal varying based on grid points. Maps have been shared with all countries,” said DS Pai, senior climate scientist at IMD, Pune.
The summer rains which set in from June 1 over India are critical because nearly 60% of India’s net arable land lacks irrigation and nearly half the population depends on a farm-based livelihood. The rains also replenish 89 “nationally important reservoirs” critical for drinking and power generation.
Many parts of the country have started recording pre-monsoon rains. IMD on Wednesday said under the influence of a fresh Western Disturbance, isolated rainfall/thunderstorm is likely over Jammu, Kashmir, Ladakh, Gilgit, Baltistan, Muzaffarabad, Himachal Pradesh and Uttarakhand during the next five days. Thunderstorm activity is likely to increase subsequently and is likely to be accompanied by gusty winds over the plains of northwest India during April 30 and May 2. Isolated thunderstorm/dust storm (speed reaching 40-50 kmph) is also likely over west and north Rajasthan during April 29 and May 2.