# Presentation: 168392

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

**Update prepared by**
**Climate Prediction Center / NCEP**
**   ****December 19, 2005**

## Outline

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

## Overview

- The MJO continues to remain weak.
- During the past week, convection in the central eastern Hemisphere remained very active with enhanced convection continuing from the eastern Indian Ocean and the Bay of Bengal across Indonesia and into the western Pacific Ocean. Suppressed convection remains near the date line. Strong westerly (easterly) low-level wind anomalies associated with the area of enhanced convection are located across the Indian Ocean / Indonesia (western Pacific Ocean) regions respectively. In many ways, conditions across the global tropics resemble those of La Nina conditions.
- Based on the latest observational evidence and statistical and dynamical forecasts, the MJO is expected to remain weak during the upcoming period.
- Although the MJO remains weak, there are potential global benefits/hazards during the forecast period. For both weeks 1 and 2, there is an increased chance of above average rainfall from the eastern Indian Ocean across Indonesia into the far western Pacific Ocean and an increased chance of below average rainfall along the equator in the central Pacific Ocean due to a pattern suggestive of La Nina conditions. During week 1, the Pacific northwest coast of the US and British Columbia, Canada have an increased chance of above average precipitation, strong winds, and high seas as multiple strong storm systems are expected to impact these regions. Also, as a result of continuing anomalous offshore flow, mainly in response to enhanced convection in the Indian Ocean, sections of southeast Africa are expected to remain drier than average during week 1.
- Tropical cyclones 7B and 25W will impact sections of southeast Asia, Malaysia, and the Bay of Bengal early during week 1 while there is an increased chance of tropical cyclogenesis in the southern Indian Ocean northwest of the coast of Australia for both weeks 1 and 2 as convection remains active and low-level westerlies become more prevalent in this region.

## 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.**

**Easterly wind anomalies have strengthened across the western Pacific Ocean**

**Westerly wind anomalies cover the equatorial Indian Ocean and stretch into Indonesia**

## 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 or westerlies (orange/red shading). **
**Stronger-than-average easterlies (blue shading).**

**Equatorial easterly anomalies remain near the date line**

**Strong westerly anomalies are evident in the Indian Ocean**

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

**Longitude**

**Time**

**Enhanced convection has become quasi-stationary across sections of the eastern Indian Ocean, Indonesia and the western Pacific Ocean**

**Weak MJO activity was evident during July and again in September as OLR anomalies propagated eastward from the Indian Ocean to the western Pacific Ocean.  **

## 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**

**During the past few weeks, the intensity and coverage of enhanced convection north of the equator has increased and is evident from the Bay and Bengal to the western Pacific Ocean **

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

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

**Easterly anomalies have been evident in the western Pacific Ocean during the past month and have strengthened during the last 10 days**

**During the past 30 days, a quasi-persistent pattern of enhanced (suppressed) convection has been evident across Indonesia (western Pacific Ocean)**

## 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**

**Most recently, along the equator, anomalous upper-level divergence (green) is strong over the Indian Ocean, Indonesia and the far western Pacific Ocean**

**Time**

**Weak to moderate MJO activity was observed from July into November. **

## 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.**

**Anomalous anti-cyclonic gyre north of the equator in southeast Asia associated in part with enhanced convection in the eastern Indian Ocean / Indonesia region. **

## 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 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 been above average in the western Pacific since June while cooler water has been observed across the eastern Pacific with a westward extension evident during November. **

**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 has been weak during the months of October and November indicated by periods of low amplitude eastward propagation

- Currently, the MJO remains weak as the projection from the most recent data continues to be  located within the unit circle

## Statistical OLR MJO Forecast

_**Statistical OLR MJO Forecast**_

**The MJO is forecast to remain weak during the next 6-10 days **

## Global Forecast System Precipitation Forecast

_**Global Forecast System Precipitation Forecast**_

**The GFS expects copious amounts of rainfall to continue across Indonesia and the western Pacific Ocean during the upcoming week**

## Potential Benefits/Hazards – Week 1

**1. An increased chance of above average rainfall extending from the eastern Indian Ocean across Indonesia into the western Pacific Ocean**
**2. An increased chance of below average rainfall in the central Pacific Ocean**
**3. An increased chance of below average rainfall across sections of Kenya and Tanzania **
**4. An increased chance of above average precipitation, strong winds, and high seas across the Pacific northwest and British Columbia**
**5. Tropical cyclones 7B and 25W will impact sections of southeast Asia, Malaysia, and the Bay of Bengal**
**6. An increased chance of tropical cyclogenesis in the southern Indian Ocean off the northwest coast of Australia**

## Potential Benefits/Hazards –Week 2

**1. An increased chance of above average rainfall extending from the eastern Indian Ocean across Indonesia into the western Pacific Ocean**
**2. An increased chance of below average rainfall in the central Pacific Ocean**
**3. An increased chance of tropical cyclogenesis in the southern Indian Ocean off the northwest coast of Australia**

## Summary

- The MJO continues to remain weak.
- During the past week, convection in the central eastern Hemisphere remained very active with enhanced convection continuing from the eastern Indian Ocean and the Bay of Bengal across Indonesia and into the western Pacific Ocean. Suppressed convection remains near the date line. Strong westerly (easterly) low-level wind anomalies associated with the area of enhanced convection are located across the Indian Ocean / Indonesia (western Pacific Ocean) regions respectively. In many ways, conditions across the global tropics resemble those of La Nina conditions.
- Based on the latest observational evidence and statistical and dynamical forecasts, the MJO is expected to remain weak during the upcoming period.
- Although the MJO remains weak, there are potential global benefits/hazards during the forecast period. For both weeks 1 and 2, there is an increased chance of above average rainfall from the eastern Indian Ocean across Indonesia into the far western Pacific Ocean and an increased chance of below average rainfall along the equator in the central Pacific Ocean due to a pattern suggestive of La Nina conditions. During week 1, the Pacific northwest coast of the US and British Columbia, Canada have an increased chance of above average precipitation, strong winds, and high seas as multiple strong storm systems are expected to impact these regions. Also, as a result of continuing anomalous offshore flow, mainly in response to enhanced convection in the Indian Ocean, sections of southeast Africa are expected to remain drier than average during week 1.
- Tropical cyclones 7B and 25W will impact sections of southeast Asia, Malaysia, and the Bay of Bengal early during week 1 while there is an increased chance of tropical cyclogenesis in the southern Indian Ocean northwest of the coast of Australia for both weeks 1 and 2 as convection remains active and low-level westerlies become more prevalent in this region.