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The Asian-Australian Monsoon System: Recent Evolution, Current Status and Prediction. Update prepared by Climate Prediction Center / NCEP September 6, 2011. For more information, visit: http://www.cpc.ncep.noaa.gov/products/Global_Monsoons/Asian_Monsoons/Asian_Monsoons.shtml. Outline.
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The Asian-Australian Monsoon System: Recent Evolution, Current Status and Prediction Update prepared by Climate Prediction Center / NCEP September 6, 2011 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, rainfall is above normal over much of north India, along the Arabian Sea coast, over Nepal, Bangladesh and Burma. By comparison, it is somewhat below normal in over southern peninsular India, southern and southeast China. The dryness over eastern Australia has eased considerably but that over south central China continues to persist.
Precip Patterns: Last 30 Days Please see Note in Slide three. The overall 30-day precipitation pattern is similar to the 90-day pattern. The general weakness that prevailed earlier in the seasonal rainfall amounts over the peninsular southern India has eased and is approaching near normal levels. However, northwestern India particularly in the vicinity of Goa has experienced above normal rainfall in the past 30 days. Southern China continues to suffer from the lack of normal rainfall.
Precip Patterns: Last 7 Days During the last seven days, northwestern and coastal western India received excessive rainfall. Vietnam, Laos, Central and Southern China received below normal rainfall as well as parts of Indonesia and Papa New Guinea.
Rainfall Time Seriesover 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 relatively consistent with the spatial maps shown earlier.
Atmospheric Circulation The anomalously strong low level cyclonic circulation center over western India contributed to the rainfall in that region. Tropical storm Talas contributed to the rainfall activity and winds over Japan and vicinity.
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 near normal in 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 August. Green (brown) shading indicates increase (decrease) in rainfall associated with strong monsoon.
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. The NCEP Global Forecast System predicts that, in the next two weeks, the Southeast Asian and northwestern Pacific monsoon continue to hover around 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 August. 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 Southeast Asian and northwestern Pacific monsoon index will be at near or below normal levels in the next two 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 August Green (brown) shading indicates increase (decrease) in rainfall associated with strong monsoon.
Summary • During the past 90 days, rainfall is above normal over much of north India, along the Arabian Sea coast, over Nepal, Bangladesh and Burma. By comparison, it is somewhat below normal over southern peninsular India, southern and southeast China. The dryness over eastern Australia has eased considerably but that over south central China continues to persist. The overall 30-day precipitation pattern is similar to the 90-day pattern. The general weakness that prevailed earlier in the seasonal rainfall amounts over the peninsular southern India is beginning to ease and is approaching near normal levels. However, northwestern India particularly in the vicinity of Goa has experienced above normal rainfall in the past 30 days. Southern China continues to suffer from the lack of normal rainfall. • During the last seven days, northwestern and coastal western India received excessive rainfall. Vietnam, Laos, Central and Southern China received below normal rainfall as well as parts of Indonesia and Papa New Guinea. The anomalously strong low level cyclonic circulation center over western India contributed to the heavy rainfall in that region. Tropical storm Talas contributed to the rainfall activity and winds over Japan and vicinity. The NCEP GFS models are predicting near to above normal rainfall over the Indian subcontinent, as the southwest monsoon is beginning to wind down.
