# Presentation: 019502

## Madden/Julian Oscillation: Recent Evolution, Current Status and Forecasts

**Update prepared by**
**Climate Prediction Center / NCEP**
**   ****September 26, 2005**

## Outline

** ****Overview**
** ****Recent Evolution and Current Conditions**
** ****Madden Julian Oscillation Forecast **
** ****Summary**

## Overview

- The MJO was weak during most of June, July, and August. During September, however, the MJO has strengthened.
- The MJO continues to be active at weak to moderate strength as upper-level divergence (convergence) regions have propagated eastward from the Indian Ocean into the western hemisphere (Eastern Pacific Ocean into the Indian Ocean). Currently suppressed (enhanced) convection is located in regions of the eastern Indian and western Pacific Ocean (across Central America and west central Africa). The recent behavior of the MJO is expected to continue during the next 1-2 weeks.
- Impacts associated with this continued evolution of the current MJO include the following. During week 1, potential benefits/hazards in the global tropics associated with the MJO signal include an increased chance of above average rainfall across Central America, Northern South America and central Africa due to a general region of upper-level divergence due to the enhanced phase of the MJO. On the other hand, an increased chance of below average rainfall exists across India due to the suppressed phase of northward propagating convection associated with the MJO in the eastern Hemisphere.
- Additional potential benefits/hazards not directly related to the MJO during week 1 include tropical cyclone activity in both the western and eastern Pacific associated with  the evolution of existing storms. Moreover, there is a heightened chance of tropical cyclone development in sections of both the western Pacific and Atlantic Oceans due to positive SST anomalies and anticipated weaker vertical wind shear. Also, an increased chance of above average rainfall exists in the tropical eastern Indian Ocean and the western Pacific mainly associated with the redevelopment of positive SST anomalies.
- During week 2, there is an increased chance of above average rainfall across the  eastern Indian Ocean and below average rainfall in the western Pacific north of the equator associated with the continued evolution of the MJO. There is also an increased chance of above average tropical cyclone activity in the  western Atlantic due to continued warm SST anomalies and anticipated weaker vertical wind shear.

## 850-hPa Vector Wind Anomalies  (m s-1)

**850-hPa Vector Wind Anomalies  (m s****-1****)**

**Note that shading denotes the magnitude of the anomalous wind vectors.**

**Flow anomalies in the  equatorial Indian Ocean and Indonesia are consistent with suppressed convection.**

**Westerly anomalies in the tropical eastern Pacific strengthened  associated with enhanced convection.**

**Anomalies in South Asia have weakened.**

## Low-level (850-hPa) Zonal (east-west) Wind Anomalies (m s-1)

**Low-level (850-hPa) Zonal (east-west) Wind Anomalies (m s****-1****)**

**Longitude**

**Time**

**Weaker-than-average easterlies (orange/red shading). **
**Stronger-than-average easterlies (blue shading).**

**In late July and early August, a period of westerly anomalies were evident in the western Pacific.**

**Anomalies associated with the MJO in the eastern Indian Ocean, Indonesia, and Pacific Ocean propagated eastward during the last three weeks. **

**Westerly anomalies have redeveloped in the eastern Pacific during the second half of September. **

**Easterly anomalies developed in the Indian Ocean during the last several days. **

## Outgoing Longwave Radiation (OLR) Anomalies (7.5°S-7.5°N)

**Outgoing Longwave Radiation (OLR) Anomalies (7.5°S-7.5°N****)**

**Drier-than-average conditions (orange/red shading) **
**Wetter-than-average conditions (blue shading)**

**Longitude**

**Time**

**The MJO was strong from late March through mid-May but has been very weak during June, July and August.**

**Convection that developed near the beginning of September in the Indian Ocean  propagated eastward during early September. **

**Convection in the Indian Ocean and Maritime Continent is in the suppressed phase during the last two weeks. **

## Outgoing Longwave Radiation (OLR) Anomalies (2.5°N-17.5°N)

**Outgoing Longwave Radiation (OLR) Anomalies (2.5°N-17.5°N****)**

**Drier-than-average conditions (orange/red shading) **
**Wetter-than-average conditions (blue shading)**

**Longitude**

**Time**

**A period of enhanced convection  north of the equator in the far western Pacific was evident during late July and early August. **

**During late August and early September, enhanced convection north of the equator  in the western Pacific.**** **

**Enhanced convection in the Eastern Pacific.**** **

**Suppressed convection has shifted north from the equatorial Indian Ocean into the Bay of Bengal. **

## Anomalous OLR and 850-hPa Wind: Last 30 days

**Anomalous OLR and 850-hPa Wind: Last 30 days**

**Convection across the east-central Pacific increased during the last 10 days.**

**Westerly anomalies in the eastern Pacific and Indonesia.**

**Enhanced convection developed in the Bay of Bengal, South China Sea, and the western Pacific north of the equator during the last 10 days. **

**Westerly anomalies associated with enhanced convection in the eastern Pacific.**

**Suppressed convection across the eastern Pacific and Indonesia increased during the last 10 days.**

## 200-hPa Velocity Potential Anomalies (5°S-5°N)

**200-hPa Velocity Potential Anomalies (5°S-5°N****)**

**Negative anomalies (green shading) indicate favorable conditions for precipitation.**

**Positive anomalies (brown shading) indicate unfavorable conditions for precipitation.**

**Longitude**

**The MJO was weak in June.  Regions of upper level divergence and convergence were generally stationary. **
**Weak eastward propagation of upper level convergence and divergence is evident from July through August. **
**Moderately strong upper level divergence developed in the Indian Ocean at the beginning of September and propagated eastward during the last three weeks.**
**Upper-level convergence is now evident in the Indian Ocean during the last week.**

**Time**

## 200-hPa Vector Winds and Anomalies  (m s-1)

**200-hPa Vector Winds and Anomalies  (m s****-1****)**

**Note that shading denotes the magnitude of the anomalous wind vectors.**

**Anomalies in the equatorial Indian Ocean associated with suppressed convection**

**Easterly anomalies in the equatorial eastern Pacific**

## Heat Content Evolution in the Eq. Pacific

**Through 2004 and 2005 there were several cases of eastward-propagating oceanic Kelvin waves (indicated by dashed black lines in the figure).**
**Each Kelvin wave was initiated when the easterlies weakened over the equatorial Pacific in association with Madden-Julian Oscillation (MJO) activity.**
**During February 2005, a strong Kelvin wave (initiated by persistent westerly anomalies near the date line unrelated to the MJO) developed and continued to strengthen during March and reached the  South American coast during early April.  Heat content has become above average in the western Pacific during July, August, and early September. **

**Heat Content Evolution**** ****in the Eq. Pacific**

**Longitude**

**Time**

## MJO Index (Magnitude and Phase)

**MJO Index (Magnitude and Phase)**

- The current state of the MJO as determined by an index based on Empirical Orthogonal Function (EOF) analysis using combined fields of near-equatorially-averaged 850 hPa zonal wind, 200 hPa zonal wind, and satellite-observed outgoing longwave radiation (OLR) (Wheeler and Hendon, 2004).
- The axes represent the time series of the two leading modes of variability and are used to measure the amplitude while the triangular areas indicate the phase or location of the enhanced phase of the MJO. The farther away from the center of the circle the stronger the MJO. Different color lines indicate different months.

- The MJO was weak during the months of June, July, and August.
- The MJO strengthened in early September.
- During the last two weeks the MJO has continued  propagating eastward but has weakened. Now the MJO is located in Western Hemisphere.

## Empirical Forecast Based on the Real-time Multivariate MJO index

**The amplitude of the MJO is forecast to remain small. **
**During week 1, the convection associated with the MJO is forecast to be in the suppressed phase in the western Pacific and the enhanced phase in the eastern Pacific.**
**During week 2 the convection is forecast to redevelop in the Indian Ocean.  **

## Potential Benefits/Hazards – Week 1

**Tropical cyclone activity associated with the evolution of the existing storms in the western Pacific**
**Increased chance of above average rainfall over Central America**
**Tropical cyclone activity associated with the evolution of the existing storms in the eastern Pacific **
**Increased chance of above average tropical cyclone activity in the  western Atlantic**
**Increased chance of above average rainfall in west central Africa**
**Increased chance of above average rainfall in the equatorial eastern Indian Ocean**
**Increased chance of above average rainfall in the equatorial western Pacific**
**Increased chance of below average rainfall in India**

_**Potential Benefits/Hazards – Week 1**_

**2**

**6**

**4**

**3**

**8**

**5**

**7**

**1**

## Potential Benefits/Hazards –Week 2

_**Potential Benefits/Hazards –Week 2**_

**Increased chance of above average rainfall in the eastern Indian Ocean**
**Increased chance of below average rainfall in the western Pacific north of the equator**
**Increased chance of above average tropical cyclone activity in the western Atlantic and Caribbean Sea region**

**1**

**2**

**3**

## Summary

- The MJO was weak during most of June, July, and August. During September, however, the MJO has strengthened.
- The MJO continues to be active at weak to moderate strength as upper-level divergence (convergence) regions have propagated eastward from the Indian Ocean into the western hemisphere (Eastern Pacific Ocean into the Indian Ocean). Currently suppressed (enhanced) convection is located in regions of the eastern Indian and western Pacific Ocean (across Central America and west central Africa). The recent behavior of the MJO is expected to continue during the next 1-2 weeks.
- Impacts associated with this continued evolution of the current MJO include the following. During week 1, potential benefits/hazards in the global tropics associated with the MJO signal include an increased chance of above average rainfall across Central America, Northern South America and central Africa due to a general region of upper-level divergence due to the enhanced phase of the MJO. On the other hand, an increased chance of below average rainfall exists across India due to the suppressed phase of northward propagating convection associated with the MJO in the eastern Hemisphere.
- Additional potential benefits/hazards not directly related to the MJO during week 1 include tropical cyclone activity in both the western and eastern Pacific associated with  the evolution of existing storms. Moreover, there is a heightened chance of tropical cyclone development in sections of both the western Pacific and Atlantic Oceans due to positive SST anomalies and anticipated weaker vertical wind shear. Also, an increased chance of above average rainfall exists in the tropical eastern Indian Ocean and the western Pacific mainly associated with the redevelopment of positive SST anomalies.
- During week 2, there is an increased chance of above average rainfall across the  eastern Indian Ocean and below average rainfall in the western Pacific north of the equator associated with the continued evolution of the MJO. There is also an increased chance of above average tropical cyclone activity in the  western Atlantic due to continued warm SST anomalies and anticipated weaker vertical wind shear.