1. Dr. K.K. Singh Head, Agromet
Monsoon
Dr. K.K. Singh
Head, Agromet

2. Long range forecast
The first stage operational forecasts for the southwest monsoon season (June – September) rainfall are issued on 22 April 2015
Quantitatively, the monsoon seasonal rainfall is likely to be 93% of the Long Period Average (LPA) with a model error of ± 5%. The LPA of the season rainfall over the country as a whole for the period is 89 cm.
Sl.
Predictor
Period 1.
The Sea Surface Temperature (SST) Gradient between North Atlantic and North Pacific
December + January 2.
Equatorial South Indian Ocean SST
February 3.
East Asia Mean Sea Level Pressure
February + March 4.
Northwest Europe Land Surface Air Temperature
January 5.
Equatorial Pacific Warm Water Volume

3. 5 category probability forecasts for the Seasonal (June to September) rainfall over the country as a whole
Category
Rainfall Range
(% of LPA)
Forecast
Probability (%)
Climatological
Deficient
< 90 33 16
Below Normal 35 17
Normal 28
Above Normal 3
Excess
> 110 1

4. Forecast of the Onset Date of Southwest Monsoon - 2015 over Kerala using statistical model
The southwest monsoon is likely to set over Kerala on 30th May
with a model error of ± 4 days. Forecast issued on 14 May 2015
6 predictors used are:
Minimum Temperature over North-west India
Pre-monsoon rainfall peak over south Peninsula
Outgoing Long wave Radiation (OLR) over south China Sea
Lower tropospheric zonal wind over southeast Indian ocean
Upper tropospheric zonal wind over the east equatorial Indian
Ocean
6. Outgoing Long wave Radiation (OLR) over south-west Pacific region

5. The operational forecasts for the event issued during all the last nine years (2005 to 2014)
Actual Onset Date
Forecast Onset Date
2005
7th June
10th June
2006
26th May
30th May
2007
28th May
24th May
2008
31st May
29th May
2009
23rd May
2010
2011
2012
5th June
1st June
2013
3rd June
2014
6th June

6. The Northern Limit of Monsoon (NLM) continue to pass through Lat 06
The Northern Limit of Monsoon (NLM) continue to pass through Lat 06.0°N/ Long. 60.0°E,  06.0°N/ Long. 70.0°E, Lat. 07.0°N/Long. 80.0°E, Lat. 10.0°N/ Long. 86.0°E, Lat. 13.0°N / Long. 89.0°E and Lat. 18.0°N / Long. 95.0°E.

7. Rainfall for previous week
Rainfall for the period 01 to 27 May

8. Current Forecast
During the past 24 hours, winds in the lower tropospheric
levels have become more westerlies/south westerlies 
leadinging to down stream convergence and increase in rainfall over Lakshadweep area and southern parts of
 peninsular India. 
Persistence of convection indicates that conditions are 
becoming favourable for the onset of southwest monsoon  over Kerala around 5th June.

9. ENSO Forecast

10. Model ENSO predictions

11. Extended Range Forecast (ERF) Outlook for June 2015
Issued by NWP Division, IMD, New Delhi
27 May, 2015
(Forecast for June 2015)

12. Current Multi-model ensemble extended range forecast
IITM’s CFSv2
Based on Initial Condition of Pentad close to Wednesday
(11 members), T382L64 (1)
(11 members), T126L64 (2)
IC=26 May
Regrid into 0.5x0.5
Calculate daily anomaly for all the three models based on corresponding model hindcast climatology
Prepare weekly mean and anomaly rainfall for 4 weeks
On Every Thursday valid from Friday
MME : Based on 6 Models Outputs
Anomaly for
Month 1
IITM’s GFSv2bc
Based on Initial Condition of Pentad close to Wednesday
(11 members), T126L64 (3),
(11 members), T126L64 (4),
IC=26 May
JMA’s Ensemble Prediction System (EPS) Based on Wednesday
(50 members), T159L60 (5)
IC=27 May
NCEP CFSv2 Based on Wednesday
(16 members), T126L64 (6)
IC=27 May

13. MME forecast mean & anomaly rainfall for June 2015 ,
IC = 27 May, 2015

14. MME forecast mean & anomaly rainfall for June 2015 ,
IC=27 May, 2015
AISMR =
NE India =
NW India =
CE India =
SP India = -7.24

15. Summary
The experimental forecast for June 2015 indicates close to deficient rainfall for June 2015 with an all India departure of -21%. (SD for June is about 23%).
Monsoon progress is likely to be slow.
We must also understand the limited forecast skill for the monthly forecast and it is only a broad outlook, which is being prepared as required by many users.

16. Weekly rain forecast during June 2015

17. Weekly rain forecast during June 2015

18. Real-time forecast based on 31st May 2015 initial condition
This MME forecast has been prepared using the CFS (T126 & T382) and GFSbc (T126 & T382) (each 11 members) .
Real-time forecast based on 31st May initial condition

19. Daily evolution of rainfall and wind at 850hPa (by MME)

20. Key points from the present forecast
After onset the LPS is likely to intensify and move towards Oman coast. This system may dissipate around 11th June and till then the monsoon activity will be weaker than normal over India.
It is likely that by 17th June the offshore trough along the west coast will be established and thereafter monsoon trough will start establishing over the Gangetic plains.
The rainfall will be mainly confined to North-East and southern peninsula for the next days.
Large-scale MISO also indicates north-ward propagation of convection from southern ocean to peninsula in next 15 days and weakening thereafter.
Convection associated with MJO is expected to move eastward to the Indian ocean till 12th June, however further movement to the maritime continent is not favoured due to El Nino induced strong convection towards central Pacific.

21. Thanks…..

22. Daily evolution of minimum and maximum temperature (by MME)

23. Daily evolution of minimum and maximum temperature Anomaly (by MME)

24. Predicted pentad wise temperature anomaly (by MME)

25. Predicted pentad wise rainfall (by MME)

26. Experimental ERFS Forecast for June and JJAS - 2015 with May Start

27. General Circulation Models (GCMs) used for the experimental forecast:
CCM3v6 (24 members) 
ECHAM4p5_CA_SST (24 members)
ECHAM4p5_CFS_SST (24 members)
CFSV2 (24 members)
COLA-RSMAS-CCSM3(6 members)
GFDL_CM2p1_aer04(10 members)
GFDL-CM2p5-FLOR-A06 (12 members)
GFDL-CM2p5-FLOR-B01 (12 members)
IMD-SFM(10 members)
ECMWF(15 members)
IITM-ERPAS (43 members that is only used as one of the product in monthly deterministic forecast)  

28. Precipitation Forecast for June (lead 1) - 2015
In allusion of deterministic precipitation forecast, normal rains are recognized to have in all parts of the country except HP, Uttarakhand, Entire UP, Bihar, East MP, Chhattisgarh, Orissa, Vidarbha, Gangetic WB, Jharkhand, and Saurashtra & Kutch where deficit rainfall is expected. On the other hand, excess rainfall is expected over West Rajasthan, SI Karnataka, Rayalseema, Tamilnadu. For the country as a whole, the forecast of precipitation is expected about 94% of long period average (LPA).

29. Precipitation Climatology (mm/day) for June
Probabilistic Precipitation Forecast for June (lead 1) (IITM-ERPAS is not included)
In reference of probabilistic rainfall forecast, signals of below normal precipitation are prevailing over Uttarakhand, East UP, Bihar, SHWB, Gangetic WB, Jharkhand, Telangana, Marathwad, East MP, Chhattisgarh, Orissa, Vidarbha. Probability of excess rainfall is high over East Rajasthan, J&K, HP, Punjab, Assam& Meghalaya, NI & SI Karnataka, Rayalseema, Tamilnadu and Kerala, Konkan &Goa, Coastal Karnakata. There is absence of any clear signals for the remaining parts of the country. At all India level, probability for near normal rainfall is high.

30. Deterministic Precipitation Forecast (percentage departure) for JJAS (lead 1) -2015
In allusion of deterministic precipitation forecast, normal rains are recognized to have in all parts of the country except Punjab, Haryana, CHD & Delhi, Uttrakhand and Entire UP where deficit rainfall is expected.
Whereas, excess rainfall is expected over Kerala. For the country as a whole, the forecast of precipitation is expected about 96% of long period average (LPA).

31. Precipitation Climatology (mm/day) for JJAS
Probabilistic Precipitation Forecast for JJAS (lead 1)- 2015
In reference of probabilistic rainfall forecast, signals of below normal precipitation are prevailing over Punjab, Haryana, CHD & Delhi, Uttarakhand, Entire UP, Bihar, East MP, SHWB, Assam & Meghalaya. Probability of above normal rainfall is high over J&K, Arunachal Pradesh, NMMT, Jharkhand, Orissa, West MP, Madhya Maharashtra, Konkan & Goa, NI Karnataka, Kerala and Tamilnadu. At all India level, probability for near normal rainfall is high.

32. Performance of ERFS Forecast – Month wise 2009-2014
JULY
JUNE

33. Performance of ERFS Forecast – Month wise 2009-2014 cont..
AUGUST
SEPTEMBER

34. Performance of ERFS Forecast – Seasonal 2009-2014
JJAS

35. Confidence Map in ERFS for real time prediction of summer monsoon season from 2009-14
JUNE
JULY
AUGUST
SEPTEMBER

36. No of subdivisions matched in observed rainfall category
Confidence Map in ERFS for real time prediction of summer monsoon season from
JJAS
No of subdivisions matched in observed rainfall category
Experimental ERFS
JJAS 24
June 11
July 18
August 17
September 14