# Presentation: 153677

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

**Update prepared by**
**Climate Prediction Center / NCEP**
**   ****July 10, 2006**

## Outline

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

## Overview 

- The latest observations indicate a continued weak MJO.
- Based on the latest observations and model forecasts, the MJO is expected to remain weak during the next 1-2 weeks.
- Potential hazards during week 1 include an increased chance for above normal rainfall over Southeast Asia, the east Pacific, southern Mexico, and Central America. Tropical Storm Bilis is forecast to strengthen and may impact Taiwan and southeast China. Meanwhile, over the east Pacific, an increased chance for tropical cyclogenesis exists for both weeks 1 and 2.
- During week 2, an increased chance of above average rainfall will extend from South Asia into Southeast Asia.
- Also, the west Pacific may benefit from a period of suppressed tropical cyclone activity especially entering 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**

- Westerly anomalies across the western Pacific.

- Easterly anomalies have weakened in the east Pacific.

## 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 anomalies have strengthened across the west Pacific.

- Easterly anomalies have developed over 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**

- Eastward propagation of OLR anomalies associated with the MJO was evident from late January through March.

- Enhanced convection has diminished over the west Pacific.

- Suppressed convection has spread across the Indian 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 (/red shading) **
**Wetter-than-average conditions (blue shading)**

**Longitude**

**Time**

- Suppressed (enhanced) convection has developed over South Asia (west Pacific).

## Anomalous OLR Wind: Last 30 days

**Anomalous OLR ****Wind: Last 30 days**

- During mid to late June, suppressed convection was evident in the east Pacific.

- Enhanced convection has been replaced by suppressed convection over the Indian Ocean and Maritime Continent.

## 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**

**Time**

- Weak to moderate MJO activity was observed during January and February.

- The MJO was incoherent during much of March and April.

- MJO activity strengthened during May and June but remains weak.

## 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.**

- Across the east Pacific, strong cyclonic circulation has weakened.

- Westerly anomalies have spread over Africa and the western Indian Ocean.

## Heat Content Evolution in the Eq. Pacific

- Above normal heat content expanded into the eastern Pacific beginning in April associated with Kelvin wave activity.

**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 remains weak.

## Statistical OLR MJO Forecast

- A statistical MJO forecast indicates weak MJO activity during the next 1-2 weeks.

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

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

- Convection is expected to develop across the equatorial Indian Ocean.

- Heavy rainfall expected in the eastern Pacific.

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

## Potential Benefits/Hazards – Week 1Valid July 11 – July 17, 2006

- 1. Tropical Storm Bilis will likely strengthen and impact Taiwan and southeast China
- 2. An increased chance for above normal rainfall for the equatorial Indian Ocean, Southeast Asia, southeast China and the Philippines
- 3. An increased chance for tropical cyclogenesis for the east Pacific
- 4. An increased chance for above normal rainfall over the east Pacific, southern Mexico, and Central America

## Potential Benefits/Hazards – Week 2Valid July 18 – July 24, 2006

- 1. An increased chance for above normal rainfall for South and Southeast Asia
- 2. An increased chance for tropical cyclogenesis in the east Pacific.

**SEE**
**TEXT**

## Summary

- The latest observations indicate a continued weak MJO.
- Based on the latest observations and model forecasts, the MJO is expected to remain weak during the next 1-2 weeks.
- Potential hazards during week 1 include an increased chance for above normal rainfall over Southeast Asia, the east Pacific, southern Mexico, and Central America. Tropical Storm Bilis is forecast to strengthen and may impact Taiwan and southeast China. Meanwhile, over the east Pacific, an increased chance for tropical cyclogenesis exists for both weeks 1 and 2.
- During week 2, an increased chance of above average rainfall will extend from South Asia into Southeast Asia.
- Also, the west Pacific may benefit from a period of suppressed tropical cyclone activity especially entering week 2.