1. 1 The Asian-Australian Monsoon System: Recent Evolution, Current Status and Prediction Update prepared by Climate Prediction Center / NCEP September 26, 2011 For more information, visit: http://www.cpc.ncep.noaa.gov/products/Global_Monsoons/Asian_Monsoons/Asian_Monsoons.shtml http://www.cpc.ncep.noaa.gov/products/Global_Monsoons/Asian_Monsoons/Asian_Monsoons.shtml

2. 2 Outline Recent Evolution and Current Conditions Monsoon Prediction Summary Climatology

3. 3 Precip Patterns: Last 90 Days With the Asian summer monsoon season almost over in the next week or so, during the past 90 days, rainfall has been above normal across much of north and central India, along the Arabian Sea coast, over Nepal, Bangladesh, Burma and Thailand. By comparison, it is somewhat below normal in over southern peninsular India, and well below normal over southern and southeast China.

4. 4 Precip Patterns: Last 30 Days The overall 30-day precipitation pattern is somewhat similar to the 90-day pattern, even though the recent 30 day positive anomalies over India are much stronger. Southern India and southern China continue to suffer from the lack of normal rainfall.

5. 5 Precip Patterns: Last 7 Days During the last seven days, a large positive rainfall anomaly center over eastern India is noted as it was forecast by the NCEP GFS last week.

6. 6 Rainfall Time Series over 5x5 lat-lon boxes Note: This unified land-only daily precipitation dataset is different from the CMAP dataset used in the previous three spatial maps. The time series of precipitation over the various regions is relatively consistent with the spatial maps shown earlier.

7. 7 Atmospheric Circulation The low level cyclonic center over eastern India along the Bangladesh border produced heavy rainfall in the region this past week.

8. 8 NCEP/GFS Model Forecasts Bias-Corrected Precip. Anom. for Weak 1 & Week 2 Week-1 Week-2

9. 9 Prediction of Large-Scale Monsoon Circulation Upper panel: Webster-Yang monsoon index (Webster and Yang 1992) defined as U850 (0- 20ºN, 40-110ºE) – U200 (0-20ºN, 40-110ºE). Positive (negative) values indicate strong (weak) than normal monsoon. Lower panel: Correlation between rainfall and Webster-Yang monsoon index (Webster and Yang 1992; shading) and regression of 850-mb winds on the monsoon index (vectors) for September. Green (brown) shading indicates increase (decrease) in rainfall associated with strong monsoon. The NCEP Global Forecast System predicts that the Webster-Yang monsoon index will be trending down in the next two weeks.

10. 10 Prediction of South Asian Monsoon Index Upper panel: South Asian monsoon index (Goswami et al. 1999) ) defined as v850 (10- 30ºN, 70-110ºE) – v200 (10-30ºN, 70-110ºE). Positive (negative) values indicate strong (weak) than normal monsoon. Lower panel: Correlation between rainfall and South Asian monsoon index (Goswami et al., 1999; shading) and regression of 850-mb winds on the monsoon index (vectors) for September. Green (brown) shading indicates increase (decrease) in rainfall associated with strong monsoon. The NCEP Global Forecast System predicts that, in the next two weeks, the Southeast Asian and northwestern Pacific monsoon will stay below normal in the next two weeks.

11. 11 Prediction of East Asia – NW Pacific Monsoon Upper panel: East Asia – Western North Pacific (EAWNP) monsoon index (Wang et al. 2008) defined as U850 (5-15ºN, 40-80ºE) – U850 (20-30ºN, 70-90ºE). Positive (negative) values indicate strong (weak) than normal monsoon. Lower panel: Correlation between rainfall and East Asia – Western North Pacific monsoon index (Wang et al. 2008; shading) and regression of 850-mb winds on the monsoon index (vectors) for August Green (brown) shading indicates increase (decrease) in rainfall associated with strong monsoon. The NCEP Global Forecast System predicts that, in the next two weeks, the Southeast Asian and northwestern Pacific monsoon index will be much above normal levels in the next two weeks.

12. 12 Summary With the Asian summer monsoon season almost over in the next week or so, during the past 90 days, rainfall has been above normal across much of north and central India, along the Arabian Sea coast, over Nepal, Bangladesh, Burma and Thailand. By comparison, it is somewhat below normal in over southern peninsular India, and well below normal over southern and southeast China. The overall 30-day precipitation pattern is somewhat similar to the 90- day pattern, even though the recent 30 day positive anomalies over India are much stronger. Southern India and southern China continue to suffer from the lack of normal rainfall. During the last seven days, a large positive rainfall anomaly center over eastern India is noted as it was forecast by the NCEP GFS last week. The low level cyclonic center over eastern India along the Bangladesh border produced heavy rainfall in the region this past week. The summer monsoon is well on its withdrawal phase as forecast by the NCEP GFS model precipitation in the next two weeks with much below normal amounts over much of the summer monsoon region (particularly India) except for above normal precipitation over southern China where it is needed.

13. 13 Demise of the Asian Monsoon

14. 14 Onset of the Australian Monsoon

15. 15 Climatology