Met forecasts below-normal rains during 2014 southwest monsoon

The India Meteorological Department (IMD) has forecast a likely fall in the average rainfall during the 2014 monsoon season (June to September) over the country as a whole to 88 per cent (± 5 per cent) of the normal long period average (LPA).

The experimental long range forecast for rainfall in the 2014 southwest monsoon season was jointly forecast by IMD and the Earth System Science Organization (ESSO) under the ministry of earth sciences (MoES).

The experimental ensemble forecast is based on IMD SFM indicates that the quantity of monsoon seasonal rainfall is likely to be 95 per cent of the LPA with a model error of ± 5 per cent.  The LPA of the season rainfall over the country as a whole for the period 1951-2000 is 89 cm.

ESSO-IMD will issue the update forecasts in June 2014 as a part of the second stage forecast. Along with the update forecast, separate forecasts for the monthly (July and August) rainfall over the country as a whole and seasonal (June-September) rainfall over the four geographical regions of India will also be issued.

ESSO-India Meteorological Department (IMD) issues various monthly and seasonal operational forecasts for rainfall during the southwest monsoon season.  Operational models are critically reviewed regularly and further improved through in-house research activities.  Operational forecasts for the southwest monsoon season (June – September) rainfall are issued in two stages. The first stage forecast is issued in April and the second stage forecast is issued in June.

The experimental forecast based on the coupled dynamical model forecasting system suggest that the monsoon rainfall during the 2014 monsoon season (June to September) averaged over the country as a whole is likely to be 96 per cent ± 5 per cent of long period model average (LPMA). The experimental five category probability forecasts for the 2014 monsoon season rainfall over the country as a whole using the experimental dynamical prediction system are 33 per cent (deficient), 20 per cent (below normal), 24 per cent (normal), 6 per cent (above normal) and 17 per cent (excess).

Since 2004, IMD has been generating experimental dynamical ensemble forecast for the southwest monsoon rainfall using the seasonal forecast model (SFM) of the Experimental Climate Prediction Center (ECPC), USA.