Madden-Julian Oscillation (MJO)

NOAA CLIMATE PREDICTION CENTER • SUBSEASONAL

Madden-Julian Oscillation

Track the eastward-moving tropical convective signal, its atmospheric circulation response, and the model forecast of where the MJO may propagate next.

Primary index RMM Phase & Amplitude 8 phases • Indian Ocean → Pacific → Western Hemisphere

CPC Expert Analysis Weekly MJO Update Recent evolution, status and predictions ↗ Weeks 2–3 Global Tropics Hazards Outlook Tropical cyclone and precipitation outlook ↗ Phase Impacts CPC MJO Composites SLP, OLR, precipitation and circulation ↗

MJO PHASE & FORECAST

Where is the signal going?

Outside the center circle indicates a stronger RMM signal. Counter-clockwise motion represents eastward propagation.

**Observed MJO Phase** Observed MJO phase and amplitude using the Wheeler-Hendon RMM index.

**GEFS Phase Forecast** GEFS ensemble forecast of the RMM MJO index and its forecast spread.

1 West. Hem. / Africa

2–3 Indian Ocean

4–5 Maritime Continent

6–7 Western Pacific

8 West. Hem. / Africa

ATMOSPHERIC DIAGNOSTICS

Current Tropical Signal

These fields help determine whether the RMM signal is supported by coherent tropical convection and circulation.

**OLR Anomalies** Current tropical convection pattern; negative OLR anomalies generally indicate enhanced convection.

**850-hPa Winds** Low-level tropical wind anomalies used to identify changes in trade-wind and convective circulation.

**200-hPa Winds** Upper-level tropical wind anomalies associated with divergence, convergence and wave propagation.

**200-hPa Velocity Potential** Time-longitude evolution of upper-level velocity-potential anomalies in the tropics.

**850-hPa Velocity Potential** Time-longitude evolution of lower-level velocity-potential anomalies.

**500-hPa Heights** Five-day global mid-level height pattern used to monitor broader circulation changes.

**200-hPa Height/Wind** Five-day upper-level circulation and wind pattern.

MODEL GUIDANCE

MJO Forecast Evolution

Forecast products isolate MJO-related anomalies and should be considered alongside ENSO and other background climate signals.

**GEFS OLR Forecast** Forecast MJO-related tropical convection anomalies reconstructed from RMM1 and RMM2.

**Velocity Potential Forecast** Empirical Wave Propagation forecast of 200-hPa velocity potential.

U.S. PHASE COMPOSITES • OND

Temperature & Precipitation

Historical composites for October–December. They show tendencies, not a deterministic local forecast.

**Phase & Temperature** Historical U.S. temperature composites and significance by RMM phase for the current three-month season.

**Phase & Precipitation** Historical U.S. precipitation composites and significance by RMM phase for the current three-month season.

WHY WATCH THE MJO?

A bridge between weather and climate

The MJO is an intraseasonal tropical disturbance that can influence convection, jet-stream patterns, U.S. temperature and precipitation tendencies, and tropical-cyclone activity. Its impacts depend on season, phase, amplitude and the background climate state.

RMM Phase & Amplitude

The phase diagram tracks the location and strength of the large-scale tropical signal.

OLR Convection

OLR anomalies help identify enhanced and suppressed tropical thunderstorm activity.

850 Low-Level Winds

Low-level wind anomalies show changes in the tropical easterlies and westerlies.

200 Upper-Level Signal

Upper-level winds and velocity potential highlight divergence and the broader atmospheric response.