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This report by the Climate Prediction Center provides an update on the recent evolution, current status, and prediction of the Asian-Australian monsoon system. It includes information on precipitation patterns, atmospheric circulation, and model forecasts. For more information, visit the provided link.
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The Asian-Australian Monsoon System: Recent Evolution, Current Status and Prediction Update prepared by Climate Prediction Center / NCEP August 2, 2010 For more information, visit:http://www.cpc.ncep.noaa.gov/products/Global_Monsoons/Asian_Monsoons/Asian_Monsoons.shtml
Outline • Recent Evolution and Current Conditions • Monsoon Prediction • Summary • Climatology
Precip Patterns: Last 90 Days During the past 90 days, precipitation was above average (1979-95 climatology) over much of the Arabian Sea particularly the eastern part, 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. Another noteworthy feature this summer season is the unusually excessive rainfall over the middle east region extending into northern Pakistan (right).
Precip Patterns: Last 30 Days During the past 30 days, precipitation was above average over much of tropical Asia except India, Indo-China peninsula, and the Philippines. 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.
Precip Patterns: Last 5 Days This past week, unusually heavy monsoon associated rainfall fell over northern Pakistan, leading to serious flooding and loss of lives. Widespread rains also fell over much of India, thus slowly lifting the season’s total rainfall from very large deficits to near normal level in just one week.
Rainfall Time Seriesover 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 Indo-China peninsula. Lower panel: In general , so far this monsoon season, rainfall over much of middle east is well above normal. Particularly, in northern Pakistan, excessive monsoon rainfall led to serious flooding and loss of lives.
Atmospheric Circulation The low level summer monsoon circulation picked up its vigor this past week and the circumstances leading to above monsoon rainfall over northern Pakistan is still not very clear.
NCEP/GFS Model Forecasts Bias-Corrected Precip. Anom. for Weak 1 & Week 2 Week-1 Week-2
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. The NCEP Global Forecast System predicts that the Webster Yang Monsoon index will be at or below normal for the next two weeks. 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.
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. The NCEP Global Forecast System predicts that the South Asian monsoon index will be near normal in the next two weeks. 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.
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. 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. 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.
Summary • This past week the monsoon rains that fell all over the Indian subcontinent, lifted up the season’s total from large deficits to near normal levels. Rainfall totals over eastern central India and eastern Indo China peninsula continue to be in a deficit hole. However, the excessively large amounts of monsoon rainfall over northern Pakistan resulted in dangerous flooding and lots of lost lives.
