UPDATE LONG RANGE FORECAST              FOR2011 SOUTHWEST MONSOON RAINFALL         21st June, 2011
Long Range Forecasts Issued For                All India Season Rainfall  All India                            All India  ...
Forecast for the 2011 South-west monsoon      rainfall issued on 19th April, 2011      South-west monsoon season (June    ...
Monsoon So Far      Advancement of     IMD had forecasted that the                          monsoon will set over Kerala ...
Monsoon So Far:        Cumulative Rainfall till 20th June, 2011                                                 Cumulative...
Second Stage Forecasts to be issued….                 All India                                          Update for All In...
Second Stage Forecasts: Method….a)    Forecast update for the southwest monsoon      season (June-September) rainfall over...
Predictors Used for the Update Forecast for theSeason (Jun-Sept) Rainfall over the Country as a WholeS.No                 ...
Geographical Locations                    of the 6 Predictors                                           929th June, 2010
Ensemble Forecasting System for           Seasonal Rainfall over Country as a whole:                               Linear ...
RAINFALL (% DEP. FROM LPA)              -25                    -20                          -15                           ...
Probabilistic Forecast Based on            5- Parameter Ensemble Forecasting system:                   Predefined Rainfall...
IMD SFM Experimental Forecast: JJAS 2011                  Rainfall over country as a whole Close to Normal                ...
National Climate Research Centers             That Provide Experimental LRF  Indian Institute of Tropical Meteorology (II...
International Climate Research Centers           That Provide Experimental LRFWorld Meteorological Organization (WMO)’s L...
Experimental Forecasts from  Statistical and Dynamical ModelsThe experimental forecasts show large divergence (from defic...
Climatological Probabilities   Normal to Above Normal        Normal                        Below Normal
ENSO- Neutral Conditions over Pacific                 oAs of Now, ENSO-Neutral                 conditions prevails. 22-Jun...
Forecast of ENSO- Neutral Conditions                           oHigh probability of                           ENSO- Neutra...
Indian Ocean Dipole                      Latest forecasts do not                      suggest development of              ...
Years Subsequent to La Nina and Monsoon ?         La Nina +1 Year   ISMR                1955       110.1   Two (1964 & 19...
Natural Variability of Indian Summer Monsoon          Rainfall: Epochal Variation                                 31-YEAR ...
Summary of the Update Forecasts for              2011 Southwest Monsoon Rainfalli) Southwest Monsoon Season Rainfall Rain...
Summary of the Update Forecasts for 2011       Southwest Monsoon Rainfall iii)Rainfall over Broad Geographical     Regions...
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Long range forecast 2011 southwest monsoon rainfall
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Long range forecast 2011 southwest monsoon rainfall

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Long Range Forecast 2011 Southwest Monsoon Rainfall

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Long range forecast 2011 southwest monsoon rainfall

  1. 1. UPDATE LONG RANGE FORECAST FOR2011 SOUTHWEST MONSOON RAINFALL 21st June, 2011
  2. 2. Long Range Forecasts Issued For All India Season Rainfall All India All India June – September Rainfall April Update for All India June – September Rainfall June 222-Jun-11
  3. 3. Forecast for the 2011 South-west monsoon rainfall issued on 19th April, 2011 South-west monsoon season (June to September) rainfall for the country as a whole most likely to be Normal (96-104% of Long Period Average (LPA)). Quantitatively, it is likely to be 98% of the LPA with a model error of ± 5%. 22-Jun-11
  4. 4. Monsoon So Far Advancement of  IMD had forecasted that the monsoon will set over Kerala on Monsoon 2011 31st May with a model error of ±4 days.  Southwest monsoon over Andaman Sea was delayed by about 10 days.  Set over Kerala on 29th May 2011. 3 days before its normal date of 1st June.  As on 20th June 2011, the northern limit of monsoon (NLM) passes through 22.0°N/60.0°E, Porbandar, Veraval, Dahanu, Nasik, Adilabad, Nagpur, Jabalpur, Khajuraho, Kanpur, Shahjahanpur, Mukteshwar and Lat 31.0°N/ Long. 80.0°E. 429th June, 2010
  5. 5. Monsoon So Far: Cumulative Rainfall till 20th June, 2011 Cumulative (1-20 June) Regions Rainfall (% of LPA) Country as a 111 whole Northwest India 126 Central India 124 South Peninsula 123 North East India 91 529th June, 2010
  6. 6. Second Stage Forecasts to be issued…. All India Update for All India June – September Rainfall All India Monthly (July & August) Rainfall 4 Geographical Regions June – September Rainfall for Four Geographical Regions 622-Jun-11
  7. 7. 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%. 729th June, 2010
  8. 8. Predictors Used for the Update Forecast for theSeason (Jun-Sept) Rainfall over the Country as a WholeS.No Predictor Period F/N/U 1 North Atlantic SST December + January Favorable 2 Equatorial SE Indian Ocean SST February + March Neutral 3 East Asia Mean Sea Level February + March Neutral Pressure 4 North Atlantic Mean Sea Level May Unfavorable Pressure 5 Nino 3.4 SST Tendency (March to May) – Unfavorable (December to February) 6 North Central Pacific wind at 1.5 May Neutral Km above sea level 829th June, 2010
  9. 9. Geographical Locations of the 6 Predictors 929th June, 2010
  10. 10. Ensemble Forecasting System for Seasonal Rainfall over Country as a whole: Linear Models ALL POSSIBLE ENSEMBLE MR MODEL MODELS AVERAGE OF (63) BEST MODELSPREDICTORS MEAN (6) FORECAST PPR ALL POSSIBLE ENSEMBLE MODEL MODELS AVERAGE OF (63) BEST MODELS Non-Linear 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. 10 29th June, 2010
  11. 11. RAINFALL (% DEP. FROM LPA) -25 -20 -15 -10 -5 0 5 10 15 20 1981 25 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996YEAR 1997 1998 1999 (1981-2010): JUNE 2000 ACTUAL 2001 2002 2003 2004 2005 2006 2007 AVE_EMR+EPPR 2008 2009 2010 ERFORMANCE OF ENSEMBLE FORECAST SYSTEM
  12. 12. Probabilistic Forecast Based on 5- Parameter Ensemble Forecasting system: Predefined Rainfall Categories Category Category Deficient Less than 90% Below Normal 90%-96% Normal 96%-104% Above Normal 104%-110% Excess more than 110%22-Jun-11
  13. 13. IMD SFM Experimental Forecast: JJAS 2011 Rainfall over country as a whole Close to Normal 1329th June, 2010
  14. 14. National Climate Research Centers That Provide Experimental LRF 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 Center for Development of Advanced Computing (C-DAC), Pune.22-Jun-11
  15. 15. International Climate Research Centers That Provide Experimental LRFWorld Meteorological Organization (WMO)’s LeadCentre for Long Range Forecasting - Multi-ModelEnsemble (LRFMME), KoreaNational Centers for Environmental Prediction (NCEP),USA International Research Institute for Climate andSociety (IRI), USAMeteorological Office, UK, the European Center forMedium Range Weather Forecasts (ECMWF), UKMeteo FranceThe Experimental Climate Prediction Center (ECPC),USA, and Asian-Pacific Economic Cooperation (APEC) ClimateCentre, Korea22-Jun-11
  16. 16. Experimental Forecasts from Statistical and Dynamical ModelsThe experimental forecasts show large divergence (from deficient to excess rainfall) with dynamical models particularly coupled models indicating normal to excess rainfall.
  17. 17. Climatological Probabilities Normal to Above Normal Normal Below Normal
  18. 18. ENSO- Neutral Conditions over Pacific oAs of Now, ENSO-Neutral conditions prevails. 22-Jun-11
  19. 19. Forecast of ENSO- Neutral Conditions oHigh probability of ENSO- Neutral Conditions likely to prevail during the monsoon season and rest of the this year.
  20. 20. Indian Ocean Dipole Latest forecasts do not suggest development of either a positive or a negative Indian Ocean Dipole event during the 2011 monsoon season. In the absence of strong monsoon forcings from both Pacific and Indian Oceans, intraseasonal variation may become more crucial during this southwest monsoon season and lead to increased uncertainty in the monsoon forecasts.22-Jun-11
  21. 21. Years Subsequent to La Nina and Monsoon ? La Nina +1 Year ISMR 1955 110.1 Two (1964 & 1971) of the 11 La Nina 1956 113.6 years prior to 2010 was immediately 1957 97.6 followed by El Nino years and the 1965 81.8 nation-wide season rainfall during both of these years was deficient 1971 104.0 (below 90%). 1972 76.1 1974 88.0 1976 102.5 The remaining 9 La Nina years were followed by ENSO-neutral conditions. 1989 100.9 1999 95.6 2008 98.3 During 8 of these ENSO-neutral 2011 ? years, nation-wide monsoon season EXC(>+10) 2 rainfall was normal (6 years) or excess (2 years) and during the remaining one NOR (±10) 6 ENSO-neutral year (1974) it was DEF (<-10) 3 deficient. Total Years 11 22-Jun-11
  22. 22. Natural Variability of Indian Summer Monsoon Rainfall: Epochal Variation 31-YEAR MOVING AVERAGE OF SEASONAL 4 MONSOON RAINFALL 3RAINFALL ANOMALY (% DEP. FROM LPA) 2 1 0 -1 -2 -3 y = 2E-08x 5 - 5E-06x 4 + 0.0004x 3 - 0.0085x 2 + 0.0044x 2 R = 0.7663 -4 1905 1910 1915 1920 1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 YEAR ENDING 31-YEAR SLIDING WINDOW Presently Rainfall in the Below Normal Epoch of its Natural Variability
  23. 23. Summary of the Update Forecasts for 2011 Southwest Monsoon Rainfalli) Southwest Monsoon Season Rainfall Rainfall over the country as a whole for the 2011 southwest monsoon season (June to September) is most likely to be below normal (90-96% of LPA). Quantitatively, monsoon season rainfall for the country as a whole is likely to be 95% of the long period average with a model error of ±4%.ii) Monthly (July & August) Rainfall Rainfall over the country as a whole in the month of July 2011 is likely to be 93% of its LPA and that in the month of August is likely to be 94% of LPA both with a model error of ± 9 %. 24 25th June, 2010
  24. 24. Summary of the Update Forecasts for 2011 Southwest Monsoon Rainfall iii)Rainfall over Broad Geographical Regions Over the four broad geographical regions of the country, rainfall for the 2011 Southwest Monsoon Season is likely to be 97% of its LPA over North-West India, 95% of its LPA over North-East India, 95% of its LPA over Central India and 94% of its LPA over South Peninsula, all with a model error of ± 8 %. 2529th June, 2010
  25. 25. Thank you
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