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El Nino Effect: Below Normal Rainfall Predicted by IMD
Jun 10, 2014

Ministry of State for Science & Technology and Earth Sciences released the 2nd stage Long range forecast for the 2014 Southwest Monsoon. Rainfall over the country as a whole for the 2014 southwest monsoon season (June to September) is likely to be below normal (90-96% of LPA). The forecast prepared by the Earth System Science Organisation (ESSO) under the India Meteorological Department (IMD):

  • Rainfall over the country as a whole for the 2014 southwest monsoon season (June to September) is likely to be below normal (90-96% of LPA). 

  • Quantitatively, monsoon season rainfall for the country as a whole is likely to be 93% of the long period average with a model error of ±4%. 

  • Region wise, the season rainfall is likely to be 85% of LPA over North-West India, 94% of LPA over Central India, 93% of LPA over South Peninsula and 99% of LPA over North-East India all with a model error of ± 8 %.

  • The monthly rainfall over the country as whole is likely to be 93% of its LPA during July and 96% of LPA during August both with a model error of ± 9 


ESSO-India Meteorological Department (IMD) issues the operational long range forecasts for the southwest monsoon season (June-September) rainfall over the country as a whole in two stages; in April and in June.  In June, in addition to the update for the forecast for the season rainfall over the country as a whole issued in April, forecasts for the monthly rainfall for July & August over the country as a whole, and forecast for the season rainfall for the 4 broad geographical regions of India (NW India, NE India, Central India and South Peninsula) are issued. 


The update forecast for the southwest monsoon season (June-September) rainfall over the country as a whole is issued using a 6-parameter Ensemble Forecasting System. The 6 predictors used are: NE Pacific to NW Atlantic SST Anomaly Gradient (December+January), Southeast equatorial Indian Ocean Sea Surface Temperature (February), East Asia Mean Sea Level Pressure (February+March), Central Pacific (Nino 3.4) Sea Surface Temperature Tendency (March to May-December to February), North Atlantic Mean Sea Level Pressure (May) and North central Pacific 850 zonal wind gradient (May). 


Sea Surface Temperature Conditions in the Pacific & Indian Oceans: The ESSO-IITM coupled dynamical model predicts moderate El-Nino conditions in the tropical Pacific for summer months. Almost all ensembles (51 members) except one ensemble predict warm SST conditions in the Nino 3 and Nino 3.4 region. This provides confidence that chances of El Nino occurring during monsoon are very high (more than 70%). On the other hand conditions in the tropical Indian Ocean are warmer than normal uniformly throughout the basin and therefore ruling out any possibility of positive Indian Ocean Dipole conditions in the tropical Indian Ocean during monsoon season. 


Monsoon Mission Experimental Coupled Dynamical Model Forecast: The experimental forecast based on the ESSO-IITM coupled dynamical model 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% ± 5% 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 29% (deficient), 13% (below normal), 35% (normal), 19% (above normal) and 4% (excess).


The list of states included in each of these four geographical regions is given below.

  • Northwest India: Jammu and Kashmir, Himachal Pradesh, Punjab, Rajasthan, Haryana, Chandigarh, Delhi, Uttarakhand and Uttar Pradesh. 

  • Northeast India: Arunachal Pradesh, Meghalaya, Assam, Nagaland, Manipur, Mizoram, Tripura, Sikkim, West Bengal, Bihar and Jharkhand.

  • Central India: Gujarat, Madhya Pradesh, Chhattisgarh, Maharashtra, Goa and Odisha.

  • South Peninsula: Andhra Pradesh, Karnataka, Tamil Nadu, Kerala, Lakshadweep and Andaman and Nicobar Islands. 

 

 

 


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