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19 April 2013



Outlook issued for southwest monsoon rainfall

Large-scale summer monsoon rainfall for South Asia and the June-September season as a whole is most likely to be within the normal range, with a slight tendency to be – in the higher side of the normal range, according to the South Asian Climate Outlook Forum.

In terms of spatial distribution of rainfall, there is a likelihood for below normal rainfall over some areas of northwestern parts of South Asia, including much of Pakistan, and above normal rainfall over some areas along Himalayan region, including Nepal and Bhutan. Below-normal rainfall conditions are also expected in the southernmost parts of India and the adjoining island areas including much of Sri Lanka and northern parts of Maldives. Rainfall conditions close to the long-period average are more likely over the remaining parts, including most of India, according to the outlook (see Figure 1). 

The consensus statement on the 2013 southwest monsoon rainfall over South Asia was developed through an expert assessment at a meeting of the South Asian Climate Outlook Forum 18-19 April in Kathmandu, Nepal. It is based on forecasts from different climate models and takes into account prevailing global climate conditions such as sea-surface temperature conditions over the equatorial Pacific and the Indian Oceans, winter and spring snow cover and surface temperature anomalies over Northern Hemisphere. However, it must be stressed that there is uncertainty partly because of the spring time predictability limit and partly due to the likely absence of El Niño/La Niña conditions in the Pacific during the monsoon. El Niño/La Niña events significantly influence the Indian summer monsoon.

More detailed information on the summer monsoon outlook on a national scale will be provided by National Meteorological Services (NMHSs).

Fig.1. Consensus outlook for 2013 Southwest Monsoon Rainfall over South Asia

Regional Climate Outlook Forums

Climate predictions are of substantial benefit to many parts of the world in risk management and adaptation to cope with the impacts of climate variability and change. WMO therefore supports regional climate outlook forums to produce a regional assessment of the state of the regional climate for the upcoming season and to provide a network between climate service providers and user-sector representatives.

Asia is a large continent with large climatological differences on a sub-regional scale. Therefore WMO's Regional Association II (Asia) recommended sub-regional Climate Outlook Forums. Implementation of South Asian Climate Outlook Forum (SASCOF) in 2010 is a step in that direction with specific focus on the climate information needs of nations affected by the Asian summer monsoon climate. The long-term mean patterns of the summer monsoon rainfall over South Asia (Fig.2), characterized by remarkable spatial variability, provide the general reference points at the respective locations for the rainfall anomalies indicated in the outlook.

Fig. 2. RainfallClimatology over South Asia
(Source: APHRODITE's Water Resources home page)









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