1. Long Range Forecast Update for the 2009 Southwest Monsoon Rainfall India Meteorological Department Presents

2. April June All India June – September Rainfall Update for All India June – September Rainfall All India Monthly (July & August) Rainfall June – September Rainfall for Four Homogeneous Regions Long range Forecast Schedule In addition, Forecast for Date of Monsoon Onset over Kerala in May 1 st Stage Forecast 2 nd Stage Forecast

3. Long Range Forecast of 2009 South-west Monsoon Season (June-September) Rainfall issued on 17 th April, 2009 IMD’s operational Long Range Forecast for the 2009 South-west Monsoon season (June-September) is that the rainfall for the country as a whole is likely to be Near Normal. Quantitatively, monsoon season rainfall is likely to be 96% of the Long Period average (LPA) with a model error of ± 5 %.

4. S.NoPredictorUsed for forecasts in F/N/U 1NW Europe Land Surface Air Temperatures (January) April Neutral 2Equatorial Pacific Warm Water Volume (February +March) April Neutral 3East Asia Mean Sea Level Pressure (February + March) April and June Unfavorable 4North Atlantic SST (December +January)April and June Favorable 5Equatorial SE Indian Ocean SST (February + March) April and June Neutral 6Central Pacific (Nino 3.4) SST Tendency (Mar+Apr+May) – (Dec+Jan+Feb) June Unfavorable 7North Atlantic Mean Sea Level Pressure (May) June Unfavorable 8North Central Pacific wind at 1.5 Km above sea level (May) June Unfavorable Predictors Used in the Ensemble Forecasting System for the Seasonal Rainfall over the Country as a Whole

5. Rajeevan et al. ( 2006), Climate Dynamics Geographical Locations of the 8 Predictors

6. Second Stage Forecasts: Method a)Forecast update for the southwest monsoon season (June-September) rainfall over the country as a whole using a 6-parameter ensemble statistical model with a model error of ± 4%. b)Forecast for the monthly rainfall over the country as a whole for the months of July & August using separate principle component regression models with a model error of ± 9%. c) Forecasts for the southwest monsoon season (June- September) rainfall for the following four broad geographical regions of India using separate multiple linear regression models with a model error of ± 8%.

7. PREDICTORS (5/6) MR MODEL PPR MODEL ENSEMBLE AVERAGE OF BEST MODELS MEAN FORECAST ALL POSSIBLE MODELS (31/63) ALL POSSIBLE MODELS (31/63) Ensemble Forecasting System for Seasonal Rainfall over Country as a whole: The average of the ensemble forecasts from best out all possible MR (multiple regression) models and that from PPR (projection pursuit regression) models gives the final forecast. Linear Models Non-Linear Models

8. Excess : Above 110% of LPA (16% Prob) Above Normal: 104-110% of LPA (17% Prob) Near Normal: 96-104% of LPA (33% Prob) Below Normal: 90-96% of LPA (16% Prob) Deficient: Below 90% of LPA (17% Prob) Definitions of Rainfall Categories based on 1901-2005 data

9. 2 nd Stage Forecasts

10. IMD’ s Experimental Dynamical Model Forecasts May SST Persisted 10 Initial Conditions 21 – 30 May 2009 Forecasts suggest positive rainfall anomalies over most parts of the country, except along some part of west coast where the anomalies are positive. For the country as a whole, the ensemble dynamical forecast suggests normal monsoon season rainfall (104% of LPA).

11. 2009 Rainfall Predictions from Various Institutes  IMD has also taken into account the experimental forecasts prepared by the national institutes like Indian Institute of Tropical Meteorology (IITM), Pune, Indian Institute of Science (IISc), Bangalore, Space Applications Centre (SAC), Ahmedabad, National Aerospace Laboratories (NAL), Bangalore, Centre for Mathematical Modelling and Computer Simulation (CMMACS), Bangalore, National Centre for Medium Range Weather Forecasting (NCMRWF), Noida and Centre for Development of Advanced Computing (C-DAC), Pune and  Operational/experimental forecasts prepared by international institutes like World Meteorological Organization (WMO)’s Lead Centre for Long Range Forecasting - Multi-Model Ensemble (LRFMME), the National Centers for Environmental Prediction (NCEP), USA, International Research Institute for Climate and Society (IRI), USA, Meteorological Office, UK, the European Center for Medium Range Weather Forecasts (ECMWF), UK, the Experimental Climate Prediction Center (ECPC), USA, and Asian-Pacific Economic Cooperation (APEC) Climate Centre, Korea.

12. 7 Models were used for prepareing the multi- model ensemble: ECHAMp5 CCM3v6 NCEP NSIPP-1 COLA ECPC GFDL IRI, US: Multi-Model Probability Forecast: July to August, 2009 Below normal rainfall over most parts of the country.

13. 3 Models: ECMWF UKMO Meteo-France Below normal rainfall over the north and northwestern parts of the coutnry. Normal to above normal rainfall over all other areas.

14. WMO Lead Center for LRF-MME: JAS Models: From 10 GPCs, Beijing ECMWF Exeter Melbourne Montreal Moscow Seoul Tokyo Toulouse Washington Below normal rainfall over North and northwestern parts of the country. Normal rainfall over south Peninsula and northeast.

15. In general, the experimental forecasts based on statistical models suggest below normal monsoon season rainfall over the country as whole and that based on the dynamical models suggest normal to above normal rainfall. 2009 Rainfall Predictions from Various Institutes

16. La Nina Conditions over Pacific and Prediction 1 st stage forecast oCurrently Atmospheric and oceanic conditions reflect neutral ENSO conditions.

17. Latest ENSO Forecast oForecasts from both dynamical and statistical models suggest high probability (about 60%) for El Nino conditions to prevail during the monsoon season oAbout 40% probability for ENSO neutral conditions. oLa Niña is ruled out.

18. Indian Ocean Dipole IOD forecast: weak positive IOD during the monsoon season FRCGC, Japan: June, 2009

19. Second Stage Long Range Forecast for 2009 South-west Monsoon Season (June –September ) Rainfall 25 th June, 2009

20. Summary of the Update Forecasts for 2009 Southwest Monsoon Rainfall i)South-West Monsoon Season Rainfall IMD’s long range forecast update for the 2009 south- west monsoon season (June to September) is that the rainfall is likely to be below normal. 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%. The Long period average rainfall over the country as a whole for the period 1941-1990 is 89 cm. ii)Monthly (July & August) Rainfall Rainfall over the country as a whole in the month of July 2009 is likely to be 93% of its LPA and that in the month of August is likely to be 101% of LPA both with a model error of ± 9 %.

21. Summary of the Update Forecasts for 2009 Southwest Monsoon Rainfall iiI)Rainfall over Broad Geographical Regions Over the four broad geographical regions of the country, rainfall for the 2009 South-West Monsoon Season is likely to be 81% of its LPA over North-West India, 92% of its LPA over North-East India, 99% of its LPA over Central India and 93% of its LPA over South Peninsula, all with a model error of ± 8 %.

22. Thank you

23. Epochal Variation of ISMR

25. RegionPeriod Issued on ForecastActual All India June to September 16 April, 2008 99% of LPA ± 5% 98% of LPA 30 June, 2008 100% of LPA ± 4% All IndiaJuly 30 June, 2008 98% of LPA ± 9%83% of LPA NW India June to September 30 June, 2008 96% of LPA ± 8%105% of LPA NE India101% of LPA ± 8%97% of LPA Central India101% of LPA ± 8%96% of LPA S. Peninsula98% of LPA ± 8%96% of LPA The forecast for onset over Kerala was 29 th May. The actual monsoon onset over Kerala was 31 st May. Verification of 2008 Operational Forecasts