1. Seasonal Predictions for South Asia
(JJAS-2010)
Sarat C. Kar
National Centre for Medium Range Weather Forecasting
(NCMRWF)
Ministry of Earth Sciences
Government of India
Presented at South Asia Climate Outlook Forum (SASCOF),
April 13-15, 2010, Pune, India

2. Probabilistic Prediction: 2009 Monsoon issued in April 2009

3. Monsoon- 2010 Rainfall prediction
Model Used- The NCMRWF Seasonal Prediction Model (InGLM1)
at T80L18 resolution (1.5x1.5 degree lat-lon)
The model has been integrated using
the NCMRWF Initial Conditions (IC)
From April 02, 03, 04, 05, 06 and 07, 2010
(6 different initial conditions)
The model is forced with
predicted Sea Surface Temperatures.
Three different SST scenarios have been used for each IC.
Total 18 member ensemble runs have been carried out.
Seasonal mean rainfall anomalies have been computed
with respect to Model climatology of 23 seasons
( ) with 18 member ensemble.
Rainfall Anomalies for JJAS-2010 based on these runs were
prepared on April 10, 2010

4. SST Forecasts from March to December 2010 (from iri.ldeo.columbia.edu)
Models indicate a range of possibilities of ENSO for JJAS-2010.
Some predict present El Nino to continue but weaken; Some predict ENSO Neutral Conditions and some La Nina conditions
Predictions of SST with 6 months
lead time do not have good skill

6. This Uncertainty in SST predictions has to be included in Seasonal Predictions of Monsoon. Therefore, in our methodology, different SST scenarios are created by adding and subtracting these uncertainties at each grid point of SST predictions. The control run is without any uncertainty.

7. SST anomalies for (averaged over JJAS-2010) used in our runs.

8. Rainfall Anomalies (mm/day) obtained from each ensemble member

9. Rainfall Anomalies (mm/day) obtained from ensemble mean Rainfall
using
Top: SST Scenario-1 Middle- SST Scenario-2 Bottom: SST Scenario-3
Rainfall Anomalies (mm/day) obtained from ensemble mean Rainfall
using
Top: SST Scenario-1 Middle- SST Scenario-2 Bottom: SST Scenario-3

10. Ensemble Mean Rainfall Anomalies (mm/day) Predicted by NCMRWF INGLM1 Global Model using Predicted SST Anomalies

12. Probabilistic Prediction

14. SUMMARY of JJAS-2010 Predictions From NCMRWF
Overall: All India- Possibility of Normal Rainfall
Possibility of Below-Normal Rainfall over some parts of
North-West India
Possibility of Normal Rainfall over Rest of India
Please see the caution on next slide

15. The NCMRWF Seasonal Prediction System is Experimental.
Skill of Global Dynamic Models (world-wide) in predicting Seasonal
Rainfall Anomalies over the Indian region is not very high
For Predictions, It is assumed that Sea Surface Temperatures (SST)
used are Correct. However, Skill of SST predictions is limited
(especially from March)
Model Response to correct SST forcing may not be forrect also.
An Updated Forecast shall be prepared on May 20, 2010

16. Thank You