# Presentation: 506952

## The Asian-Australian Monsoon System: Recent Evolution, Current Status and Prediction

**Update prepared by**
**Climate Prediction Center / NCEP**
**   ****16**** June 2008**

**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)_

- Contact _[Qin.Zhang@noaa.gov](mailto:Qin.Zhang@noaa.gov)__ or __[Song.Yang@noaa.gov](mailto:Song.Yang@noaa.gov)__ for questions and comments._

## Outline

** **
** ****Recent Evolution and Current Conditions**
** ****Monsoon Prediction**
** ****Summary**
** ****Climatology**

## Rainfall Patterns: Last 90 Days

**During the past 90 days, heavy precipitation occurred over much of the maritime continent, tropical eastern Indian Ocean, tropical western and southwestern Pacific, and the North Pacific storm-track region. Precipitation was above normal over most of the tropics except the western Indian Ocean, Papua New Guinea, and the equatorial Pacific east of 145E. Above-normal precipitation also appeared over ****Indian, southern China and southern Japan****. Below-normal precipitation was found over the subtropical Southern Hemisphere including Madagascar, the Indian Ocean, and Australia. Precipitation was also below normal over the Middle East, east coast of Indo-China peninsula, and the subtropical North Pacific high area.**

## Rainfall Patterns: Last 30 Days

**Heavy precipitation occurred over the ****Northern Hemisphere ****tropic ****region ****and the North Pacific storm-track region. Precipitation was above normal over  the Arabian Sea, Bay of Bengal, eastern maritime continent, tropical western Pacific, and the storm-track region. Above-normal precipitation also occurred over northern India, Nepal, southern China****, and southern Japan****. Below-normal precipitation was found over much of the Southern Hemisphere especially over the tropical Indian Ocean. Precipitation was also below**** ****normal over Sri Lanka, ****Vietnam****, and Papua New Guinea.**

## Rainfall Patterns: Last 5 Days

**Precipitation has increased significantly over southern China, southern Japan, and the Bay of Bengal during the last 5 days. Wet condition also appeared over India. Below-normal rainfall was observed over the southern Arabian Sea, ****eastern equatorial Indian ocean****, central South China Sea, Philippines, and the Philippine Sea. **

## Recent Evolution: Rainfall

**Upper right: The rainfall over southern China has been above normal associated with a northward shift of the Southeast Asian monsoon rain-band.**
**Central right: The rainfall over the central South China Sea and Philippines continued to be below normal after the monsoon rain-band shifted northward.  **
**Bottom right: The rainfall over ****northern**** India has been mainly ****above**** normal.**

**For other boxes, see: http://www.cpc.ncep.noaa.gov/products/**
**Global_Monsoons/Asian_Monsoons/90d-precip_click_map.shtml**

## The evolution of OLR indicates that monsoon has intensified over the west portion and weaken over the east portion (except over southern China) of the Asian monsoon region during the past weeks.

**The evolution of OLR indicates that monsoon has intensified over the west portion and weaken over the east portion (except over southern China) of the Asian monsoon region during the past weeks.**

## Atmospheric Circulation

**  **
** ****Cross-equatorial flow intensified over the western Indian Ocean and the stronger-than-normal Somalia Jet brought more water vapor to the eastern Arabian Sea and western India.**
** ****Anomalous lower-level anti-cyclonic patterns were observed over the coast of China and the northwestern Pacific related to the heavy rainfall over the southern China and southern Japan.**** **

## NCEP/GFS Model Forecasts  Bias-Corrected Precipitation for Week 1 & Week 2

## W-Y Monsoon Prediction

_**Upper panel:**_** Webster-Yang monsoon index (Webster and Yang 1992) defined as the mean U850-U200 over 0-20N, 40-110E. The NCEP GFS predicts that, in the next two weeks, the large-scale Asian monsoon circulation will fluctuate moderately around normal.  **

_** **__**Lower panel:**_** Correlation between precipitation and the Webster-Yang monsoon index (Webster and Yang 1992; shading) and regression of 850-mb winds against the monsoon index (vectors) for June.**

## SA Monsoon Prediction

_**Upper panel:**_** South Asian monsoon index (Goswami et al. 1999) defined as the mean V850-V200 over 10-30N, 70-110E. The NCEP GFS predicts that the South Asian monsoon circulation will weaken from a strong phase to a relatively normal phase in the next two weeks.  **

_** **__**Lower panel:**_** Correlation between precipitation and the South Asian monsoon index (Goswami et al. 1999; shading) and regression of 850-mb winds against the monsoon index (vectors) for June.**

## EA-WNP Monsoon Prediction

_**Upper panel:**_** East Asian – Western North Pacific monsoon index (Wang et al. 2008) defined as the mean difference of U850(5-15N/90-130E) – U850(20-30N/110-140E). The NCEP GFS predicts that, in the next two weeks, the monsoon circulation over East Asia and the western North Pacific will shift from normal to below-normal conditions.  **

_** **__**Lower panel:**_** Correlation between precipitation and the East Asian – Western North Pacific monsoon index (Wang et al. 2008; shading) and regression of 850-mb winds against the monsoon index (vectors) for June.**

## Summary

**Above-normal precipitation occurred over most of the tropical Asian-Australian region during the past months. Above-normal precipitation was also found over the subtropical western Pacific storm-track region last months and over the Arabian Sea last month. **
**Below-normal precipitation appeared over the subtropical southern Indian Ocean, Madagascar, Australia, and the subtropical northwestern Pacific high region. The Middle East was also drier than normal during the past months****.**** ****Wet**** condition was seen over ****the**** Bay of Bengal, ****Arabian Sea****, and ****far west North pacific**** last month as well.**
**While major rain belt further shifted to the northern tropics, the precipitation over the South China Sea continued to be below normal. **
**The rainfall over India was overall above normal, and**** the rainfall over the Bay of Bengal and southern China was significantly above normal last week.**
**The NCEP GFS predicts that the Indian monsoon circulation will weaken from a strong phase to a relatively normal phase in the next two weeks.**

## Onset Dates of ASM 

**Onset Dates of ASM**_ _

## Climatology