1. 1 The Asian-Australian Monsoon System: Recent Evolution, Current Status and Prediction Update prepared by Climate Prediction Center / NCEP 12 October 2009 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 Rainfall Patterns: Last 90 Days During the past 90 days, below-normal monsoon rainfall was observed over India, Indo- China peninsula, southern China, Northeast China, and the East China Sea. Below- normal rainfall was also observed over Indonesia, Malaysia, tropical southern Indian Ocean, and eastern Australia. Rainfall was above normal over the eastern Arabian Sea, Bangladesh, Myanmar, northern Bay of Bengal, the South China Sea, Philippines, the Philippine Sea, the western Pacific, and equatorial eastern Indian Ocean.

4. 4 Rainfall Patterns: Last 30 Days During the past 30 days, monsoon rainfall was below normal over East Asia and Indonesia. Below-normal rainfall was also found over part of India, Sri Lanka, and much of the tropical Indian Ocean. On the contrary, rainfall was above normal over the northern Bay of Bengal, the South China Sea, northern Philippines, the Philippine Sea, and the western Pacific east of 140E.

5. 5 Rainfall Patterns: Last 5 Days Rainfall was above normal over northern India, Bangladesh, northern Bay of Bengal, northern Philippines, and south of Japan. Below-normal rainfall was observed over southern India, central tropical Indian Ocean, Indo-China peninsula, southern China, and the Philippine Sea.

6. 6 Rainfall Time Series over 5x5 lat-lon boxes *This unified land-only daily precipitation dataset is different from the CMAP dataset used in the previous three spatial maps. Upper panel: Impact of typhoon has significantly enhanced the post monsoon rainfall over the Philippines. Middle panel: The accumulated rainfall over the Indo-China peninsula has been constantly below normal during the past season. Bottom panel: Southern India experienced heavy late monsoon rainfall.

7. 7 Atmospheric Circulation Large-scale tropical monsoon flow was stronger than normal, with an anomalous cyclonic pattern (centered over India and Philippines-Taiwan) over southern Asia and adjacent oceans.

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 October. Green (brown) shading indicates increase (decrease) in rainfall associated with strong monsoon. The NCEP Global Forecast System predicts that the large-scale monsoon circulation over tropical Asia will be weaker than normal in the next two weeks.

10. 10 Prediction of South Asian Monsoon Circulation Upper panel: South Asian monsoon index (Goswami et al. 1999) defined as V850-V200 over 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 October. Green (brown) shading indicates increase (decrease) in rainfall associated with strong monsoon. The NCEP Global Forecast System predicts that the monsoon-type circulation over South Asia will be weaker than normal in the next two weeks.

11. 11 Prediction of East Asian Monsoon Upper panel: East Asian monsoon index (Li and Zeng 2002; GRL). Positive (negative) values indicate strong (weak) than normal monsoon. Lower panel: Correlation between rainfall and East Asian monsoon index (Li and Zeng 2002; shading) and regression of 850-mb winds on the monsoon index (vectors) for October. 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 East Asian monsoon circulation will be near or weaker than normal.

12. 12 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 October. 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 EAWNP monsoon circulation will continue to be near or stronger than normal.

13. 13 Summary Rainfall was above normal over northern India, Bangladesh, northern Bay of Bengal, northern Philippines, and south of Japan. Below-normal rainfall was observed over southern India, central tropical Indian Ocean, Indo-China peninsula, southern China, and the Philippine Sea. The NCEP Global Forecast System predicts that, in the next two weeks, monsoon circulation will be mainly weaker than normal over southern Asia, with near normal condition over Southeast Asia.

14. 14 Retreat of the Asian Monsoon

15. 15 Climatology