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Welcome to the Boreal Summer Intraseasonal Oscillation (BSISO) forecast website. The BSISO forecast activity has been initiated in 2013 with the goal of improving our ability to understand and forecast the BSISO based on numerical models in cooperation with the CAS/WCRP Working Group on Numerical Experimentation (WGNE) Madden Julian Oscillation (MJO) Task Force, and hosted at the APEC Climate Center (APCC).


This website will be updated as additional models become available and verification statistics and various ways of displaying forecast information generated. The information is available from May to October.

Historical forecast index download (2015 ~ )

Phase Diagram

The BSISO phase diagram illustrates the consecutive development and progression of BSISO for the past 15 days of observation and the upcoming 20 days of forecast, which provides information on the location and strength of BSISO. The eight divided phases represent the location of BSISO convective center. When the index shown is within the center circle, it is indicating a weak BSISO, and when it is outside of the circle, the index is considered to be a strong BSISO.


Spatial OLR Anomalies

The spatial OLR anomalies display how far the OLR field is expected to deviate from the normal state (climate), which is the pentad mean OLR.


Heavy Rainfall Probability

The heavy rainfall probability shows the probability of occurrence for heavy rainfall events in the upcoming 1 and 2 weeks, estimated using the BSISO forecast index.



The real-time verification shows the relationship between the observed and predicted BSISO index for the recent forecasts issued in the past 20 days.
The cumulated forecast skill indicates the cumulative mean of skills for all available BSISO forecasts for all available days.

Verification scores information (PDF)

Real-time verification for BSISO indices


Cumulated forecast skills of BSISO indices for all available days