1. 1 The Asian-Australian Monsoon System: Recent Evolution, Current Status and Prediction Update prepared by Climate Prediction Center / NCEP 20 July 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, above-normal precipitation occurred over the eastern Arabian Sea, the Bay of Bengal, Bangladesh, Myanmar, the South China Sea, Philippines, the Philippine Sea, and most of the western Pacific. Below-normal precipitation was observed over eastern Africa, India, most of the India Ocean, East Asia, eastern Indo- China peninsular, Indonesia, Malaysia, and part of Australia.

4. 4 Rainfall Patterns: Last 30 Days During the past 30 days, above-normal precipitation was observed over the eastern Arabian Sea, the Bay of Bengal, Myanmar, the South China Sea, the East China Sea, Korea, and part of the western Pacific. Below-normal precipitation appeared over India, tropical southern Indian Ocean, much of Southeast Asia, eastern China, and eastern Australia.

5. 5 Rainfall Patterns: Last 5 Days Monsoon rainfall was above normal over central India, northern Bay of Bengal, the South China Sea, the Philippine Sea, and Korea. Rainfall was below normal over southern India, Sri Lanka, southern hills of the Tibetan Plateau, southern China, southern Japan, and part of Indonesia.

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: The East Asian Mei-yu has been above normal over eastern China and Korea (Changma) and near normal over southern Japan (Baiu). Middle panel: The effects of frequent tropical cyclones have overcome the dry conditions over southern China. Bottom panel: The heavy monsoon rainfall in July has offset the deficient monsoon rainfall in June over part of India including the south.

7. 7 Atmospheric Circulation Lower-tropospheric monsoon flow was stronger than normal over the eastern Arabian Sea, India, the Bay of Bengal, the South China Sea, and Southeast Asia. A cyclonic pattern (associated with Tropical Depression six and Typhoon Molave) was clearly seen over the South China Sea and adjacent regions. The cross equatorial flow over the Indian Ocean was stronger than normal.

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 July. 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 near 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 July. Green (brown) shading indicates increase (decrease) in rainfall associated with strong monsoon. The NCEP Global Forecast System predicts that the South Asian monsoon circulation will be near 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 July. 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 be changing from above normal to below normal.

12. 12 Summary In mid-July, monsoon rainfall was above normal over central India, northern Bay of Bengal, the South China Sea, the Philippine Sea, and Korea. Rainfall was below normal over southern India, Sri Lanka, southern hills of the Tibetan Plateau, southern China, southern Japan, and part of Indonesia. The NCEP Global Forecast System predicts that, in the next two weeks, the monsoon circulation over tropical Asia will be overall near normal with below normal rainfall over southern India.

13. 13 Onset of the Asian Monsoon

14. 14 Climatology