1. 1 The Asian-Australian Monsoon System: Recent Evolution, Current Status and Prediction Update prepared by Climate Prediction Center / NCEP September 13, 2010 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 During the past 90 days, above-average rainfall was observed over much of southern Asia and tropical Indian Ocean. Above-average rainfall was also seen over East Asia, western North Pacific, northwestern Australia, and part of western Asia and the Middle East. On the other hand, below-average rainfall was observed over Saudi Arabia, southern Indo-China peninsula, western subtropical Southern Indian Ocean, and equatorial western Pacific Ocean. The rainfall over much of Indonesia, Iran, and Afghanistan was highly above normal.

4. 4 Precip Patterns: Last 30 Days During the past 30 days, above-average rainfall occurred over much of the Asian monsoon region (e.g. 10S-40N, 60E- 140E), with exceptions over eastern India, southern China, Japan, and southern Indo-China peninsula. The rainfall over much of Indonesia was highly above normal. Below-average rainfall was mainly observed over the western Pacific east of 140E.

5. 5 OLR Patterns: Last 5 Days Enhanced convection was observed over northern and southern India, southern China, central-western Indonesia, equatorial western Indian Ocean, and the tropical eastern Indian Ocean off Sumatra. Suppressed convection was seen over the equatorial central-eastern Indian Ocean, Japan, and western Pacific Ocean.

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 rainfall over northern India has been continuously above average in the past days. Middle panel: The accumulated rainfall over southern China has significantly increased recently. Lower panel : The accumulated rainfall over Malaysia has been always above average in the summer.

7. 7 Atmospheric Circulation The cross-equatorial flow over western Indian Ocean and the monsoon flow over the Arabian Sea were stronger than normal, contributing water vapor to India. The trade wind over tropical Pacific was stronger than normal, leading to convergence over part of Southeast Asia. Southwesterly flow appeared from the South China Sea to Japan; and an anomalous cyclonic pattern was observed off Sumatra, affecting part of Indonesia.

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 above or 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 (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 the South Asian monsoon circulation will continue to be stronger 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 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 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 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 monsoon circulation over Southeast Asia and northwestern Pacific will continue to be weaker than normal.

13. 13 Summary During the past several days, enhanced convection was observed over northern and southern India, southern China, central-western Indonesia, equatorial western Indian Ocean, and the tropical eastern Indian Ocean off Sumatra. Suppressed convection was seen over the equatorial central- eastern Indian Ocean, Japan, and western Pacific Ocean. The NCEP Global Forecast System predicts that the monsoon circulation will continue to be stronger than normal over South Asia but weaker than normal over East-Southeast Asia and the northwestern Pacific.

14. 14 Demise of the Asian Monsoon

15. 15 Climatology