Isobel formed immediately south of the western end of Java, and to west of the active TC Hubert . Development was comparatively fast, 36 hours passing from the formation of the initial low to cyclonic strength by 0000 UTC 13 at 10.8°S and 100.4°E. After an initial south easterly track, Isobel moved onto a south westerly and deepened.
For more details see the TC Isobel Report (pdf)
Track and intensity
All times in WST - subtract 8 hours to convert to UTC.