The Madden-Julian Oscillation tracks anomalies of precipitation over the Equator. When these anomalies, dry or wet, are in certain parts of the MJO monitoring region, they are in different phases. When the MJO is in Phase 8, we typically see above normal precipitation anomalies over the Atlantic portion of the Equatorial region.
This above normal precipitation signals more convection than usual in the region, which can enhance tropical cyclone development. That is why, typically, when the MJO moves into Phases 8-2, you will see many forecasters become more optimistic on tropical cyclone development over the next few days.
This forecast of the MJO, from the ECMWF's Seasonal Ensembles, shows a very aggressive Phase 1 and Phase 2 in the forecast period, which is a very good sign for tropical development. Where this development occurs remains to be seen, but as of now, with Tropical Depression SEVEN dissipating and Invest 93 weakening, the Atlantic appears to not be prepared for significant development just yet, as the MJO is not favorable at the moment.