ESSO Government of India Earth System Science Organisation Ministry of Earth Sciences India Meteorological Department No. ESSO/IMD/NW P- Extended Range Forecast (ERF) Report No. 01 (2018)/05 E valuation of Real-Time Extended Range Forecast (ERF) of southwest monsoon, heat wave, cold wave, cyclogenesis and northeast monsoon during 2017 D. R. Pattanaik and A. K. Sahai India Meteorological Department 1 New Delhi February 2018 2 Government of India Earth System Science Organisation Ministry of Earth Sciences India Meteorological Department Evaluation of Real-Time Extended Range Forecast (ERF) of southwest monsoon, heat wave, cold wave, cyclogenesis and northeast monsoon during 2017 India Meteorological Department New Delhi February 2018 3 CONTENTS Copyright © India Meteorological Department, 2018 The right of publication in print, electronic or any other for reserved by the India Meteorological Department Short extracts may be reproduced, however the source should be clearly indicated DISCLAIMER & LIMITATIONS The contents published in this report have been checked and authenticity assured within limitations of human errors India Meteorological Department is not responsible for any errors and omissions The geographical boundaries shown in this report do not necessarily correspond to the political boundaries For Correspondence Dr. D. R. Pattanaik Scientist-E Extended Range Forecast Group (Numerical Weather Prediction) Division Head, Publication & Human Resource Development India Meteorological Department New Delhi - 110003 Email : [email protected] [email protected]/[email protected] Phone - 91-11-43824481 (Work) 91-9868554029 (Mobile) 4 Contents Acknowledgements Preface Document Control Sheet Chapter Title Page No. Chapter - 1 Extended Range Forecast (ERF) During Southwest Monsoon 10-54 2017 Chapter - 2 Extended Range Forecast of Cold Wave and Extreme Low 55-73 Temperature During Winter Season. Chapter - 3 Extended Range Forecast of Heat Wave and Extreme High 73-102 Temperature During Summer Season. Chapter - 4 Extended Range and Seasonal Forecast of Cyclogenesis 103-122 Over North Indian Ocean During 2017 Chapter - 5 Extended Range Forecast (ERF) of Northeast Monsoon over 123-136 India During Post-monsoon Season 2017 Chapter - 5 Link for Real-Time Extended Range Forecast products, 137-142 Executive Summaries of the Main Results and Future Prospects 5 Acknowledgements The authors are thankful to Dr. K. J. Ramesh, Director General, India Meteorological Department, for providing all facilities to carry out this work. Thanks are due to Dr. M. Mohapatra, Sc- G (Services) for the encouragement to carry out this work. We also sincerely acknowledge the Indian Institute of Tropical Meteorology, Pune for providing technical support in customization of model used for the Extended Range Forecast. Special thanks to Extended Range Forecast Group scientists of IITM, Pune viz., R. Phani Muralikrishna, Raju Mandal, Avijit Dey, Susmitha Joseph and Rajib Chattopadhyay The authors are also thankful to National Centre for Medium Range Weather Forecasting (NCMRWF) and Indian National Centre for Ocean Information Services (INCOIS) under the Ministry of Earth Sciences for providing the initial conditions used for the model integrations. Thanks are due to the office of Climate Research & Services (CRS), IMD Pune for providing the gridded rainfall & temperature data; office of Hydrometeorology for providing meteorological sub-division level observed rainfall data and Regional Met Centre, Chennai for providing northeast monsoon rainfall data used in our analysis. 6 Preface Just like the inter-annual variability of monsoon rainfall the Indian summer monsoon precipitation shows clear intra-seasonal variation associated with northward propagation of large-scale convective anomalies from the equator. This northward propagation is known to be accompanied by eastward propagation of convective activity along the equator (Madden Julian Oscillation; MJO) through the Rossby wave propagation. The Indian daily rainfall and MJO phases are related in a complex way. The forecasting of this intra- seasonal fluctuation of Indian rainfall is very difficult but is very useful for the country. At present there are many national/global modelling centers like, IMD, IITM, ECMWF, NCEP, JMA etc. are running atmospheric General Circulation Model (GCM) and coupled atmosphere-ocean GCMs operationally. An accurate coupling of the fast atmosphere to the slow ocean (with long memory) is essential to simulate the MJO, which in turn can simulate the intra-seasonal variability of Indian monsoon. With the efforts from the Ministry of Earth Sciences (MoES) and supports from IITM, NCMWF and INCOIS; IMD has implemented the coupled model for the real time extended range forecast from last years. The year 2017 has been an eventful year exhibiting 5% less rainfall during the monsoon season from June to September associated with many dry spells. The monsoon season also witnessed extreme rainfall events like the heavy rainfall event over Rajasthan during end of July and heavy rainfall over Mumbai during end of August. There was a large scale cold wave during the second week of January, 2017 over most parts of central and northwest India. Similarly the winter season also witnessed sudden warming by about 5 to 6 degrees above normal during last week of February (17-23 February, 2017). Though there was substantial decrease in death due to heat wave in the year 2017 compared to previous two years (2015 and 2016) the maximum temperature (Tmax) was unusually high during middle of April and also during 2nd half of May causing many deaths over India. Similarly, the cyclone ‘Ockhi over Arabian Sea during November end had very peculiar track and caused loss of life and property. In addition to the extended range forecast (ERF) of southwest monsoon the ERF of north-east monsoon rainfall over Tamil Nadu, the ERF of genesis of tropical cyclones over the north Indian Ocean and the ERF of maximum and minimum temperatures are also very crucial and useful for different sectors viz., Agriculture, Water Resources, Power and Health etc. This report highlighted the monitoring and forecasting aspects of ERF of intra-seasonal rainfall fluctuation during 2017 southwest monsoon season along with the performance of monsoon forecast on smaller spatial domains (Met-subdivision level), which is being used operationally for the Agromet advisory purpose. In addition to this, the performance of ERF of northeast monsoon over Tamil Nadu, ERF of cyclogenesis over north Indian Ocean and the ERF of heat wave in summer during 2017 using the coupled models outputs run operationally at IMD are also discussed in separate chapters. Finally, we sincerely acknowledge all the institutes of India under the Ministry of Earth Sciences viz., IITM, NCMRWF, INCOIS in contributing to strengthen ERF capability of IMD. . K. J. Ramesh Director General of Meteorology India Meteorological Department 7 8 DOCUMENT CONTROL SHEET Ministry of Earth Sciences (MoES) Earth System Science Organisation 1 ESSO Report No. ESSO/IMD/NWP- Extended Range Forecast (ERF) Report No. 01 (2018)/05 Number 2 Title of the Evaluation of Real-Time Extended Range Forecast (ERF) of southwest Report monsoon, heat wave, cold wave, cyclogenesis and northeast monsoon during 2017 3 Authors D. R. Pattanaik and A. K. Sahai 4 Originating NWP (Extended ,Range Forecast), O/o DGM, IMD New Delhi Unit . 5 Type of Technical Report Document 6 No. of pages 142/46 and Figures 7 No. of 53 References 8 Key Words Indian monsoon, Extended Range forecast, MME, Heat Wave, CFSv2, Multi-model ensemble, Heavy Rainfall, Coupled Model. 9 Security Open Classifications 10 Distribution Open 11 Date of February, 2018 Publication 12 Funding India Meteorological Department agency The monitoring and forecasting of weather on extended range time 13 Abstract scale is evaluated for the southwest monsoon rainfall, extreme high temperature in summer (heatwave), northeast monsoon rainfall and cyclogenesis over the north Indian Ocean during October to December during the year 2017 based on the outputs from the coupled models run at IMD. The suite of model used for ERF is CFSv2_T382, CFSv2_T126, GFSbc_T382 and GFSbc_T126 with a total of 16 ensemble members. The Multi-model ensemble (MME) based on these 16 ensemble members is also prepared in the real time. The MME ERF performed well in predicting the intra-seasonal rainfall activity including the onset of monsoon, dry spells of monsoon, transitions of monsoon etc. The real time ERF also clearly indicated the impending high maximum temperature over many parts of India during middle of April and also towards the second week of May, 2017. The timely warning based on skillful forecast of such extreme high temperature can be very useful to the planners and disaster managers to implement practices to prevent heat- related deaths and illnesses. The extended range forecast of northeast monsoon activity over Tamil Nadu, Cyclogenesis potential , cold wave and abnormal warming in winter also provided useful guidance in the real-time Thus, the MME ERF can be considered as one of the better tools for providing the forecast in the extended range time scales for southwest monsoon, northeast monsoon, tropical cyclogenesis and extreme temperatures. 9 Chapter – 1 EXTENDED RANGE FORECAST (ERF) DURING SOUTHWEST MONSOON 2017 Abstract The performance of Multi-model Ensemble (MME) based extended range forecasts for the 2017 southwest monsoon based coupled models (NCEP-CFS version 2; CFSv2) is discussed. The results are discussed during onset, advance, active-break and withdrawal phases of monsoon. The slight delay/weak onset of monsoon with its slow progress northward during first 10 days of June was well captured in the MME forecast with a lead time of about 15 days. Except based on the initial conditions of late May and first week of June the MME forecast performs very well in capturing the dry spell of monsoon during first half of July, revival during last week of July, dry spell of monsoon during most of August & early September and a brief active spell towards late September. Over the homogeneous regions of India the MME forecast provided useful guidance with central India indicating more promising results with the CC between observed and forecast rainfall departure is found to be significant till two weeks . The met subdivision wise forecasts for 36 met subdivisions for two weeks are being used experimentally for preparing agromet advisory to farmers. The real time extended range forecast capability of IMD will be strengthened through the collaborative work with IITM, NCMRWF and NCEP. 10