1. 1 The Asian-Australian Monsoon System: Recent Evolution, Current Status and Prediction Update prepared by Climate Prediction Center / NCEP May 31, 2011 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, and even outside of this period, the interesting and persistent rainfall observation feature has been the existence of the clear and strong dipole structure with much below normal rainfall over the large southeast China region and the much above normal rainfall over northern Australia separated by more or less near normal rainfall over the in between southeast China region. The southwest summer monsoon is just about to get set over the Indian subcontinent.

4. 4 Precip Patterns: Last 30 Days The 30-day precipitation accumulation is still seriously deficient over interior and coastal eastern China around 30N, but much improved over southeastern coastal China. Precipitation over coastal and interior eastern Australia is also highly deficient. Strong 30 day deficiencies of rainfall are also appearing over southern India. Hopefully, the summer monsoon onset over peninsular India, which is on its way, will alleviate this shortfall. Please see Note in Slide three.

5. 5 Precip Patterns: Last 7 Days Even though, according to the official Indian Met. Dept.’s press release, the monsoon onset over the Kerala coast (southwest India) has already taken place on May 29 th, the seven day observed rainfall anomalies (from the above maps) are below normal all along the peninsular western coasts of India bordering the Arabian Sea. However the Bay of Bengal branch of the Indian monsoon has been more active than normal (see next slide for daily rainfall amounts over these regions).

6. 6 Rainfall Time Series over 5x5 lat-lon boxes Note: This unified land-only daily precipitation dataset is different from the CMAP dataset used in the previous three spatial maps. The time series of precipitation over the various regions is quite consistent with the spatial maps shown earlier, even though as noted above, the rainfall data sets are from different sources and are processed differently.

7. 7 Atmospheric Circulation The Arabian sea branch of the southwest Indian summer monsoon is split into two branches skipping the Arabian sea coastal portions of peninsular India, thus leading to below normal rainfall along the coast for the same approximate seven day period.

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 March. 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 slightly below normal in the upcoming two weeks.

10. 10 Prediction of South Asian Monsoon Index 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 March 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 Southeast Asian and northwestern Pacific monsoon index will be at or slightly below normal level 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 March 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 Southeast Asian and northwestern Pacific monsoon index will be at or below normal level in the next two weeks.

12. 12 Summary During the past 90 days, and even outside of this period, the interesting and persistent rainfall observation feature has been the existence of the clear and strong dipole structure with much below normal rainfall over the large southeast China region and the much above normal rainfall over northern Australia separated by more or less near normal rainfall over the in between southeast China region. The southwest summer monsoon is just about to get set over the Indian subcontinent. The 30-day precipitation accumulation is still seriously deficient over interior and coastal eastern China around 30N, but much improved over southeastern coastal China. Precipitation over coastal and interior eastern Australia is also highly deficient. Strong 30 day deficiencies of rainfall are also appearing over southern India. Hopefully, the summer monsoon onset over peninsular India, which is on its way, will alleviate this shortfall. Even though, according to the official Indian Met. Dept.’s press release, the monsoon onset over the Kerala coast (southwest India) has already taken place on May 29 th, the seven day observed rainfall anomalies for the period ending May 29 th are below normal all along the peninsular western coasts of India bordering the Arabian Sea. However the Bay of Bengal branch of the Indian monsoon has been more slightly more active than normal. Also, while the NCEP Global Forecast System’s model forecasts are indicating positive rainfall anomalies in the upcoming week for southwestern India, it is not suggesting any major upsurge in the overall strength of the large monsoon circulation in the upcoming two weeks.

13. 13 Demise of the Asian Monsoon

14. 14 Onset of the Australian Monsoon

15. 15 Climatology