# Presentation: 245942

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

**Update prepared by**
**Climate Prediction Center / NCEP**
**   ****October 4, 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, strengthened during early September, and once again weakened during the middle of September.
- The MJO remains at weak strength and upper-level divergence (convergence) is currently located in the eastern Atlantic/central Africa (central America) regions.  Based on the latest observational evidence, the MJO is expected to strengthen as a result of the above normal SST anomalies in the Indian Ocean and eastward propagation of the current weak upper-level divergence from central Africa.
- Impacts associated with this expected strengthening of the 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 in the Indian Ocean and western Indonesia areas. During week 2, there is an increased chance of above average rainfall in the eastern Indian Ocean, southeast Asia and western Pacific regions associated with the continued evolution of the MJO.
- Additional potential benefits/hazards not directly related to the MJO include the following.  During week 1, tropical depression Otis and tropical storm Stan will impact Baja California and southern Mexico respectively with above normal rainfall and strong winds. An increased chance of above average rainfall exists across southern Mexico, areas of Central America, southern Florida, the Gulf of Mexico, and the Caribbean Sea associated with the evolution of weather systems in both the mid-latitudes and tropics along with above average local SSTs. In these same general regions there also exists an increased chance of tropical cyclone activity due to continued warm SSTs and expected weak vertical wind shear. In addition, there exists an increased chance of above average rainfall in west Central Africa due to favorable interaction with the extratropics.
- During week 2, there is an increased chance of above average tropical cyclone activity in the Gulf of Mexico, Caribbean Sea, Bay of Bengal, and the western Pacific due to warm SSTs and expected weak vertical wind shear while there remains an increased chance of above average rainfall in southern Florida, the Gulf of Mexico, and the Caribbean Sea.

## 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.**

**Westerly anomalies in the equatorial western Pacific associated with enhanced convection.**

**Westerly anomalies in the equatorial eastern Atlantic associated with enhanced convection.**

## 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 was evident in the western Pacific.**

**Anomalies associated with the MJO in the eastern Indian Ocean, Indonesia, and Pacific Ocean propagated eastward during the first half of September. **

**Westerly anomalies developed in the western Pacific 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 was 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 was in the suppressed phase during the middle of September. **

**Convection in the western Pacific developed during the last several days. **

## 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**

**Enhanced convection in the Eastern Pacific during the middle of September.**** **

**Enhanced convection in the western Pacific associated with above average SSTs during the last few days. **

**Suppressed convection north of equator in the Indian Ocean during the middle of September. **

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

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

**Westerly anomalies in the western Pacific and Indonesia during the last 10 days.**

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

**Suppressed convection across the eastern Indian Ocean and Indonesia during the last 10 days.**

**Convection across the western Pacific enhanced 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**

**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**

- _Disclaimer_:  Current data transfer issues do not allow a more recent figure at this 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.**

**Easterly anomalies in the tropical Atlantic.**

## 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 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 middle of September the MJO continued  propagating eastward but weakened.
- The MJO further weakened during the last several days and now is located in the Western Hemisphere.

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

**The MJO is forecast to be weak for the next two weeks by this statistical method. **

## Potential Benefits/Hazards – Week 1

**Tropical depression Otis will impact Baja California with above normal rainfall and strong winds.**
**Increased chance of above average rainfall in regions of southern Mexico, southern Florida, the Gulf of Mexico, and Caribbean Sea.  Also, increased chance of above average tropical cyclone activity in the Gulf of Mexico, and Caribbean Sea.  Tropical storm Stan will impact southern Mexico with above normal rainfall and high winds.**
**Increased chance of above average rainfall in west Central Africa**
**Increased chance of above average rainfall in the Indian Ocean and western Indonesia areas**
**Increased chance of tropical cyclone development in the Bay of Bengal**
**Increased chance of tropical cyclone development in the western Pacific.**

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

**5**

**6**

**1**

**3**

**4**

**5**

**2**

## Potential Benefits/Hazards –Week 2

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

**Increased chance of above average rainfall in regions of southern Florida, the Gulf of Mexico, and Caribbean Sea.  Also, increased chance of above average tropical cyclone activity in the Gulf of Mexico, and Caribbean Sea.**
**Increased chance of above average rainfall in the eastern Indian Ocean, southeast Asia and western Pacific.**
**Increased chance of tropical cyclone development in the Bay of Bengal**
**Increased chance of tropical cyclone development in the western Pacific.**

**2**

**4**

**3**

**1**

## Summary

- The MJO was weak during most of June, July, and August, strengthened during early September, and once again weakened during the middle of September.
- The MJO remains at weak strength and upper-level divergence (convergence) is currently located in the eastern Atlantic/central Africa (central America) regions.  Based on the latest observational evidence, the MJO is expected to strengthen as a result of the above normal SST anomalies in the Indian Ocean and eastward propagation of the current weak upper-level divergence from central Africa.
- Impacts associated with this expected strengthening of the 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 in the Indian Ocean and western Indonesia areas. During week 2, there is an increased chance of above average rainfall in the eastern Indian Ocean, southeast Asia and western Pacific regions associated with the continued evolution of the MJO.
- Additional potential benefits/hazards not directly related to the MJO include the following.  During week 1, tropical depression Otis and tropical storm Stan will impact Baja California and southern Mexico respectively with above normal rainfall and strong winds. An increased chance of above average rainfall exists across southern Mexico, areas of Central America, southern Florida, the Gulf of Mexico, and the Caribbean Sea associated with the evolution of weather systems in both the mid-latitudes and tropics along with above average local SSTs. In these same general regions there also exists an increased chance of tropical cyclone activity due to continued warm SSTs and expected weak vertical wind shear. In addition, there exists an increased chance of above average rainfall in west Central Africa due to favorable interaction with the extratropics.
- During week 2, there is an increased chance of above average tropical cyclone activity in the Gulf of Mexico, Caribbean Sea, Bay of Bengal, and the western Pacific due to warm SSTs and expected weak vertical wind shear while there remains an increased chance of above average rainfall in southern Florida, the Gulf of Mexico, and the Caribbean Sea.