Normal rainfall is most likely during the 2017 Southwest monsoon season (June – September) over much of South Asia, according to the South Asian Climate Outlook Forum held in Bhutan 24-26 April. The outlook was developed through an expert assessment of various observed and emerging climatic features that influence the monsoon, including the El Niño-Southern Oscillation (ENSO).
The Southwest monsoon accounts for 70-80 percent of annual rainfall in most countries of South Asia. It is a key driver of socio-economic development and well-being in the world’s most densely-populated region which is regularly hit by devastating flooding and damaging droughts.
The South Asian Climate Outlook is a consensus product based on expert assessment of the prevailing global climate conditions and forecasts from different climate models from the participating National Meteorological Services and from around the world.
Specifically, it said:
· Below-normal rainfall is most likely over broad areas of north-western, central and south-eastern parts of South Asia.
· Above-normal rainfall is most likely over broad areas of eastern and the south-western parts of the region.
· Normal rainfall is most likely over the remaining areas.
The weak La Nina conditions that prevailed over the Pacific during the latter part of 2016 weakened and turned to neutral ENSO conditions in January 2017. Currently, warm neutral ENSO conditions are prevailing. There is strong consensus among experts that neutral ENSO conditions are likely to continue through the spring season and weak El Nino conditions are likely to develop in the second half of this year. However, it is recognized that there is uncertainty about the development and timing of El Nino conditions. There is also uncertainty about the impact of development of weak El Niño conditions on the southwest monsoon season rainfall over the region.
Other regional and global factors that may affect the region were also considered, including Indian Ocean Dipole (IOD) conditions over the Indian Ocean, as well as winter and spring Northern Hemisphere snow cover. The outlook will be downscaled by national meteorological services for national forecasts.
Advance information about the likely performance of the monsoon makes it possible for decision-makers to plan agricultural, public health and other risk-management strategies. A great deal of progress has been made in understanding monsoons, but should be noted that prediction, particularly of rainfall amounts, remains a challenge.
WMO supports regional climate outlook forum all over the world as part of its drive to provide user-friendly climate services for the good of society. WMO co-sponsored the SASCOF-10 session in Bhutan under a project funded by the Department of the Environment, Government of Canada, for the implementation of the Global Framework for Climate Services (GFCS).
A copy of the full outlook is available here consensus_statement_sascof10_26APR17.pdf