1. 1 The Asian-Australian Monsoon System: Recent Evolution, Current Status and Prediction Update prepared by Climate Prediction Center / NCEP 31 August 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 most of southern Asia, especially over India, Indo-China peninsula, Malaysia, and Indonesia. Below-normal rainfall was also observed over tropical southern Indian Ocean (along 10S), eastern Australia, and subtropical northwestern Pacific. However, over Bangladesh, Myanmar, northern Bay of Bengal, the South China Sea, the Philippine Sea, and the Bismarck Sea, rainfall was clearly above normal.

4. 4 Rainfall Patterns: Last 30 Days During the past 30 days, monsoon rainfall was below normal over most of southern Asia, especially over India, southern China, Indo-China peninsula, the South China Sea, Indonesia, the Philippines, Korea, and southern Japan. The rainfall over eastern Australia and off Sumatra was also below normal. Above-normal rainfall was observed over Bangladesh, Myanmar, eastern China, eastern Philippine Sea, and equatorial central-eastern Indian Ocean.

5. 5 Rainfall Patterns: Last 5 Days Monsoon rainfall to the west of 100E including that over India was mainly near normal. Near-normal rainfall was also found over much of Southeast Asia. However, the rainfall over the northern parts of the South China Sea, Philippines, and the Philippine Sea and over eastern Indo-China peninsula, southern China, and Japan was clearly below normal.

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: In this monsoon season, the accumulated rainfall over East Asia including eastern China, Japan, and Korea was above normal. Middle panel: The accumulated rainfall over much of the Indo- China peninsula was clearly below normal this season. Bottom panel: In spite of the above-normal rainfall over part of South Asia such as Bangladesh and Myanmar, the accumulated rainfall over India was clearly below normal.

7. 7 Atmospheric Circulation Monsoon flows were weaker than normal over the Arabian Sea, the Bay of Bengal, and the South China Sea. Anomalous anti-cyclonic patterns were observed over East Asia and southern Bay of Bengal.

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 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 September. 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 or above 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 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 EAWNP monsoon circulation will be above normal.

12. 12 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 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 East Asian monsoon circulation will be mainly below normal.

13. 13 Summary In the past week, monsoon rainfall to the west of 100E including that over India was mainly near normal. Near- normal rainfall was also found over much of Southeast Asia. However, the rainfall over the northern parts of the South China Sea, Philippines, and the Philippine Sea and over eastern Indo-China peninsula, southern China, and Japan was clearly below normal. The NCEP Global Forecast System predicts that, in the next two weeks, the monsoon circulation over large-scale tropical Asia will be near normal, with weaker (stronger) than normal monsoon circulation over East (South and Southeast) Asia.

14. 14 Onset of the Asian Monsoon

15. 15 Climatology