1. 1 The Asian-Australian Monsoon System: Recent Evolution, Current Status and Prediction Update prepared by Climate Prediction Center / NCEP August 9, 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, precipitation was above average (1979-95 climatology) over Kashmir region, northern Pakistan, Bangladesh, Assam/India, much of Burma, the Arabian Sea, the Bay of Bengal, Bangladesh, equatorial Southeast Asia, eastern Indian Ocean, southeastern China, Japan, maritime Indonesia, and the northwestern Pacific storm track region. On the other hand, slightly below-average precipitation occurred over much of India, much below normal rainfall over Indo-China peninsula, the Philippines, and the subtropical western Indian Ocean and western Pacific(consistent with La Nina). The % of normal 90-day accumulated precip map (right) shows the Middle East, northern Pakistan and Kashmir region at over 200-250% of normal, as well as northwestern Australia.

4. 4 Precip Patterns: Last 30 Days During the past 30 days, precipitation was above average over much of tropical south Asia except peninsular India, eastern Indo-China peninsula, the Philippines and southeastern China. Above-average precipitation was also observed over northern India, northern Pakistan, the eastern Arabian Sea, southern and central Bay of Bengal, tropical central eastern Indian Ocean, and the northwestern Pacific storm track region. However, below-average also occurred over portions of India particularly eastern central India, equatorial western Pacific, Indochina peninsula, and northeastern Asia. Excessive precipitation and flooding continued over northern India, Pakistan and near Gujarat, India.

5. 5 Precip Patterns: Last 5 Days This past week, unusually heavy monsoon associated rainfall fell over northern Pakistan, northern Kashmir part of India as well as Gujarat. Flooding situation continued in these regions with serious damages to property and many lost lives.

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 heavy rainfall over southern and southeastern China in the second half of June contributed to the clearly above-average values of the accumulated regional rainfall. Middle panel:. Rainfall deficits continue to deepen over eastern regions of Indo-China peninsula. Lower panel : Gujarat, India continued to experience heavy rains over the last couple of months, along with the middle east region in general particularly Pakistan(not shown). These above normal rains could be associated with the 1-2 deg.C above normal SST in northern Arabian sea.

7. 7 Atmospheric Circulation Consistent with GFS forecasts posted in previous weeks, the low level trough over western India and the cyclonic circulation slightly further north (more apparent at 500 mb according to some analyses) these regions (Gujarat, Kashmir and northern Pakistan) continued to receive torrential monsoon related rains and hence experience flooding with damaging consequences for lives and property.

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 Webster Yang Monsoon index continues to be at or below normal for 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 July. Green (brown) shading indicates increase (decrease) in rainfall associated with strong monsoon. The NCEP Global Forecast System predicts that the South Asian monsoon index 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 East Asian WNP Monsoon Index will continue its up and down swing, as it has done in the past several weeks.

12. 12 Summary In the last two to three weeks, rainfall that fell over most of India brought the total amount or rainfall since June 1 st, from serious deficits to within normal levels for India as a whole. Particularly the unusual and excessive rains in the Middle East particularly over northern Pakistan and northern Kashmir/India and near Gujarat at 200-250 % of normal (for 90-day and 30-day accumulated precip amounts) has led to serious flooding in these regions. NCEP GFS model continues to predict more rains in these regions in the upcoming weeks. Whether any of these extreme events is related to over 1-2 deg.C above normal SST in the northern Arabian sea region needs to be investigated. Also southeastern China and eastern Indo China peninsula continues to be dry.

13. 13 Onset of the Asian Monsoon

14. 14 Climatology