The MJO is known as Madden-Juilian-ocsillation, it is simliar to that of the ENSO el nino or la nina. The MJO's are waves that form near the international datline and propogate eastward. These waves trigger very strong convectie thunderstorms, and because of this we can best identify them by looking at outgoing radiation maps (OLR). This whole cycle generally lasts from 30-60 days to 40-50 days it depends on many things. This effects hurricanes in-directly by changing wind patterns, SST's, amount of water vapor in certain areas and much much more. It appears to me from my study that are simliar to Kelvin waves which also forrm by the dateline but propogate poleward at faster speeds. It is very complicated in layman's terms. Here is a link on it!
http://www-das.uwyo.edu/~geerts/cwx/notes/chap12/mjo.html