India Meteorological Department New Delhi February 2018 DR Pattanaik and AK Sahai

143 Pages·2017·34.96 MB·English

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)

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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

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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.

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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

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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.

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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.

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