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Seasonal Outlook for 2010 Southwest Monsoon Rainfall

South Asian Climate Outlook Forum (SASCOF -1) 13-15 April 2010, Pune. Seasonal Outlook for 2010 Southwest Monsoon Rainfall. D. S. Pai Director, Long Range Forecasting. Long range Forecast Schedule:2010. APRIL

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Seasonal Outlook for 2010 Southwest Monsoon Rainfall

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  1. South Asian Climate Outlook Forum (SASCOF -1) 13-15 April 2010, Pune Seasonal Outlook for 2010Southwest Monsoon Rainfall D. S. Pai Director, Long Range Forecasting

  2. Long range Forecast Schedule:2010 • APRIL • The first Long Range Forecast of South-west Monsoon season (June – Sept) rainfall over the country as a whole. • May • Forecast for monsoon onset over Kerala • June • Seasonal forecast Update • Forecast for July & August rainfall for the country as a whole • Forecasts for season (June-Sept) rainfall for 4 broad geographical regions of India, viz. • NW India, NE India, Central India, South Peninsula

  3. Predictors used for April Forecast for the seasonal rainfall over the country as a whole:2010

  4. Statistical Ensemble Forecasting System for Seasonal Rainfall over Country as a whole: MR MODEL ALL POSSIBLE MODELS (31) ENSEMBLE AVERAGE OF BEST MODELS PREDICTORS (5) MEAN FORECAST PPR MODEL ALL POSSIBLE MODELS (31) ENSEMBLE AVERAGE OF BEST MODELS MR Models PPR Models The average of the ensemble forecasts from best out of all possible MR (multiple regression) models and that from PPR (projection pursuit regression) models gives the final forecast.

  5. Geographical Regions of the Predictors

  6. Performance of the April Ensemble Forecasting System: 1981-2009 RMSE = 6 % of LPA

  7. Probabilistic Forecast There is 92% probability for 2010 All India Seasonal Rainfall to be below to near normal (90% to 104%)

  8. IMD’S DYNAMICAL FORECASTING SYSTEM FOR EXPERIMENTAL LRF • The Seasonal Forecast Model (SFM) of Experimental Climate Prediction Center (ECPC) is used for this purpose • The model showed some useful skill during hindcast mode (1985-2004). • The dynamical model needs more testing and refinement.

  9. IMD SFM Forecast: Persistent Method March SST Persisted – 10 Initial Conditions (21 – 30 March 2010) Forecasts suggest Below normal rainfall over most parts of the country. Country as a whole: 68% of LPA

  10. IMD SFM Forecast: Using CFS SST Forecast (April) Forced by CFS Forecasted SST 10 Initial Conditions (21 – 30 March 2010) Forecast suggest above normal rainfall over most parts of the country Country as a whole :158% of LPA

  11. 2010 Rainfall Predictions by Various Climate Prediction Centres Based on Multi- Model Ensemble Methods

  12. IRI, US: Multi-Model Probability Forecast: June to August, 2010 7 Models were used for prepareing the multi-model ensemble: ECHAMp5 CCM3v6 NCEP NSIPP-1 COLA ECPC GFDL JJA: Climatological probabilities for entire country. JAS: Over Peninsula, Highest Probability for above normal rainfall

  13. EUROSIP forecast 3 Models: ECMWF UKMO Meteo-France Over Peninsula the rainfall is most likely to be above normal

  14. APCC JJA 2010: Issued March 2010

  15. Status of Other Important Factors that Having Influence on Monsoon

  16. ENSO Conditions over Pacific and Prediction • El Nino conditions are prevailing . • El Niño is expected to continue at least through the Northern Hemisphere spring 2010. • ENSO Neutral Conditions likely to prevail during monsoon 2010.

  17. El Nino Vs Monsoon

  18. Indian Ocean Dipole FRCGC, Japan: March, 2010 IOD forecast: Basin-wide warming in the tropical Indian Ocean in following spring and summer. There is a tendency of a negative IOD to happen in Sep-Nov 2010 associated with the La Nina development.

  19. Monthly Snow Cover Area - 2010 Departure from normal January March February March Data source: RUTGERS UNIVERSITY

  20. Epochal Variation of ISMR

  21. Conclusions • IMD probability model forecast for 2010 SW Monsoon Season (June to September) Rainfall over the Country as a Whole indicate the highest probability for below normal to near normal categories. • IMD SFM model: • Below Normal: Persistent Method • Above Normal: CFS SST • MME Forecast From Various Centers indicate above normal rainfall over Peninsula • Analysis of various factors having influence on monsoon indicate normal rainfall • The Combined Outlook:Near Normal Rainfall

  22. Thank you

  23. METHODOLOGY OF GENETIC ALGORITHMS BASED MONSOON RAINFALL PREDICTION FROM SAC AHMEDABAD • In GA method, annual monsoon is treated as a time-series whose evolution • can be expressed as a combination of a number of periodic processes. • The predictors of the annual monsoon are time-series of monsoon rainfall • over different homogeneous zones of India during previous years. • Original GA model was developed during the year 2003, but is updated • each year with the availability of new observations of rainfall. • The “prediction” shown in the diagram indicates the “hindcast skill” of • the “latest” GA model, and may be different from the actual prediction • made by GA model during previous years. • The standard error of the current model is 4%.

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