1. 1 The Asian-Australian Monsoon System: Recent Evolution, Current Status and Prediction Update prepared by Climate Prediction Center / NCEP June 14, 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, rainfall is above normal over much of the latitude band 10S-10N extending all the way from the Indian Ocean to the western Pacific, over and near Bangladesh, maritime Indonesia, eastern China, and the western North Pacific storm track region. Outside of these regions, 90 day precipitation accumulations are below normal over India, southern Indian Ocean and much of Australian continent.

4. 4 Precip Patterns: Last 30 Days During the past 30 days, the precipitation anomalies pattern is much similar to the 90 days accumulated precipitation anomalies pattern, except that the anomalies are stronger in amplitude. Even after the declared onset of the southwest monsoon over India by the India Met. Dept, the precipitation deficiencies over much of India, Burma, Thailand and Indochina, and Philippines continue to persist. However, excessive positive precipitation anomalies are noted over northeast India, Bay of Bengal, southeastern Indian ocean and maritime Indonesia.

5. 5 Precip Patterns: Last 5 Days Below-average precipitation is prevalent over much of Indian peninsula, the tropical southwestern Indian Ocean, Indo-China Peninsula, northern South China Sea, Philippines, and subtropical-extratropical northwestern Pacific. Precipitation is also deficient over southern India, clearly reflecting the weakened state of the summer monsoon. Above normal precipitation is noted over central Bay of Bengal and the Indian Ocean to the south.

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 southeastern China and much of East Asia has been mostly above average in the past 90 days. Middle panel: In the past 90 days, rainfall has been mostly below average over much of the Indo-China Peninsula. Lower panel: Except in small and narrow regions of southeastern south India, north east India, and along the India-Pakistan border, monsoon related precipitation over much of India is well below normal (see right).

7. 7 Atmospheric Circulation The northern limit of the moisture laden southwesterly flow striking the west coast of India is further south than normal, and consequently anomalous low level easterlies prevail over central India associated with a cyclonic circulation in the central Bay of Bengal and above normal precipitation in that oceanic region, but deficient rainfall over much of India.

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 Right 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. Left 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 June. 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 about just normal in the following two weeks.

10. 10 Prediction of South Asian Monsoon Circulation Right 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. Left 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 June. Green (brown) shading indicates increase (decrease) in rainfall associated with strong monsoon. The NCEP Global Forecast System predicts that the monsoon circulation over South Asia will be near normal or slightly above normal in the next two weeks.

11. 11 Prediction of East Asia – NW Pacific Monsoon Right 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. Left 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 June. 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 be weaker than normal.

12. 12 Prediction of East Asian Monsoon Right panel: East Asian monsoon index (Li and Zeng 2002; GRL). Positive (negative) values indicate strong (weak) than normal monsoon. Left 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 June. 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 below normal.

13. 13 Summary During the past 90 days, rainfall is above normal over much of the latitude band 10S-10N extending all the way from the Indian Ocean to the western Pacific, over and near Bangladesh, eastern China, and the western North Pacific storm track region. Outside of these regions, 90 day precipitation accumulations are below normal over India, southern Indian Ocean and much of Australian continent. The past 30 days anomalies pattern is very similar to the 90 days pattern, except that the amplitude is stronger. In spite of the declared onset of the southwest monsoon over India, deficiencies in the accumulated precipitation over 5-day, 30-day, and 90-day periods continue to exist over much of India except over northeast part. The northern edge of the advancement of monsoon seems to be behind by about 5-7 days. Serious shortfalls in the monsoon related precipitation totals exist over Burma, Thailand, Indochina and New Zealand as well. NCEP’s GFS forecast do not indicate any major improvement in the next week.

14. 14 Onset of the Asian Monsoon

15. 15 Climatology