# Presentation: 208804

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

**Update prepared by**
**Climate Prediction Center / NCEP**
**   ****May 8, 2006**

## Outline

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

## Overview 

- The latest observations indicate that the MJO remains weak. There is an increasingly lessening impact from La Nina.
- Based on the latest observational evidence, the MJO is expected to remain weak during the next 1-2 weeks.
- Potential hazards/benefits across the global tropics during week 1 include increased chances of above normal rainfall in northeast South America, equatorial Africa, and the western Pacific Ocean stretching from the Philippines across New Guinea. An increased likelihood of below normal rainfall exists in the eastern Indian Ocean and sections of Indonesia. Also, tropical cyclone activity may impact the area east and near the Philippines.
- Increased chances of above normal rainfall are expected to develop in the equatorial Indian Ocean during week 2.

## 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**

**Westerlies (easterlies) remained over maritime continent (western Pacific).**

**Anti-cyclonic circulations associated with easterly anomalies on the equator**

## 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)**

**Westerly (easterly) anomalies remained over maritime continent (western Pacific).**

**Easterly anomalies developed in the western 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**

**Eastward propagation of OLR anomalies was evident from mid-January  through late February**

**Enhanced convection propagated from the eastern Indian Ocean to the western Pacific during the last few weeks.**

**Enhanced convection over South America during the last two weeks.**

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

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

**Suppressed convection near the date line in the equatorial Pacific  Ocean has weakened considerably during April.**

**Enhanced convection and associated wind anomalies propagated eastward during the last 20 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**

**During April and early May, the MJO has been weak.**

**Time**

**Weak to moderate MJO activity was observed during November and January-February time periods. **

## 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 western Pacific Ocean consistent with enhanced convection.**

**Cyclonic circulation in Arabian Sea. **

## Heat Content Evolution in the Eq. Pacific

**Above normal heat content expanded into the central Pacific during April 2006. **

**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 signal has been weak during late April and early May, however, the MJO signal has strengthened during the last few days.

## Statistical OLR MJO Forecast

**A statistical MJO forecast indicates dry conditions across the Indian Ocean during week 1.  **

## Global Forecast System (GFS) Week 1 Precipitation Forecast

_**Global Forecast System (GFS) Week 1 Precipitation Forecast**_

**Relatively sparse rainfall in central eastern equatorial Indian Ocean**

**Heavy rainfall in equatorial northern Brazil**

**Abundant rainfall in equatorial Africa and western Indian Ocean**

## Global Forecast System (GFS) Week 2 Precipitation Forecast

## Potential Benefits/Hazards – Week 1Valid May 9 - 15, 2006

- 1. Increased chances of above normal  rainfall in northeast South America
- 2. Increased chances of above normal rainfall in equatorial Africa and the western Indian Ocean associated with the continued evolution of intraseasonal variability and localized above normal SSTs
- 3. Increased chances of below normal rainfall in the eastern Indian Ocean and sections of Indonesia associated with the continued evolution of intraseasonal variability.
- 4. Increased chance of above normal rainfall from Philippines across New Guinea associated with evolution of existing weather systems and diminishing impact from La  Nina
- 5. Increased chance of tropical cyclone activity east of the Philippines.

## Potential Benefits/Hazards – Week 2Valid May 16 – May 22, 2006

- 1. Above normal rainfall in the tropical Indian Ocean associated with continued evolution of intraseasonal variability, localized above normal SSTs, and convection associated with the diminishing impact from La Nina.

## Summary

- The latest observations indicate that the MJO remains weak. There is an increasingly lessening impact from La Nina.
- Based on the latest observational evidence, the MJO is expected to remain weak during the next 1-2 weeks.
- Potential hazards/benefits across the global tropics during week 1 include increased chances of above normal rainfall in northeast South America, equatorial Africa, and the western Pacific Ocean stretching from the Philippines across New Guinea. An increased likelihood of below normal rainfall exists in the eastern Indian Ocean and sections of Indonesia. Also, tropical cyclone activity may impact the area east and near the Philippines.
- Increased chances of above normal rainfall are expected to develop in the equatorial Indian Ocean during week 2.