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This report provides an update on the recent evolution and current conditions of the Asian-Australian Monsoon System, along with prediction information. It covers precipitation patterns over the last 90 days, 30 days, and 5 days, as well as atmospheric circulation and model forecasts. The report concludes with a summary of the Australian monsoon retreat climatology.
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The Asian-Australian Monsoon System: Recent Evolution, Current Status and Prediction Update prepared by Climate Prediction Center / NCEP March 22, 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, below-average precipitation was observed over the Philippine Sea, western Australia, tropical southeastern Indian Ocean, and Madagascar. On the other hand, above-average precipitation appeared over part of East Asia, much of the tropical central Indian Ocean, the Arafura Sea, eastern Australia, and equatorial western Pacific Ocean.
Precip Patterns: Last 30 Days During the past 30 days, below-average precipitation was observed over southern Asia (especially Southeast Asia), Middle East, the western Pacific, western Australia, part of subtropical Southern Indian Ocean, and Madagascar. Above-average precipitation was seen over East Asia, eastern Australia, and part of tropical-subtropical southern Indian Ocean.
Precip Patterns: Last 5 Days Below-average precipitation was observed over northern Australia, part of Southeast Asia, and the tropical western Pacific. Above-normal precipitation appeared over western Indonesia, tropical-eastern Southern Indian Ocean, Madagascar, and Japan.
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. While rainfall has been mostly below average over northern Australia and much of Southeast Asia, the accumulated precipitation was above average over East Asia.
Atmospheric Circulation The lower-tropospheric southwesterly flow was over southern China. Strong easterly anomaly over northeastern Australia was related to the tropical storm there.
NCEP/GFS Model Forecasts Bias-Corrected Precip. Anom. for Weak 1 & Week 2 Week-1 Week-2
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 monsoon circulation over Southeast Asia and northwestern Pacific will fluctuate around normal. 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.
Prediction of Australian Monsoon Upper panel: Australian monsoon index (Hung and Yanai 2004) defined as U850 averaged over 2.5ºS-15ºS, 110-150ºE. Positive (negative) values indicate strong (weak) than normal monsoon. The NCEP Global Forecast System predicts that, in the next two weeks, the Australian monsoon circulation will continue to be weaker than normal. Lower panel: Correlation between rainfall and Australian monsoon index (Hung and Yanai 2004; 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.
Summary • During the last 30 days, below-average precipitation was observed over northwestern Australia, part of Southeast Asia, and the tropical western Pacific, and above-normal precipitation appeared over western Indonesia, tropical-eastern Southern Indian Ocean, and Japan. • The NCEP Global Forecast System predicts that, in the next two weeks, the Australian monsoon circulation will change from weak to above normal.
