MikeC is right - as a system Isaac bears little resemblance to Katrina other than it's general position in the SE GoM, forecast path and landfall, and time of year (last week in August)

After Katrina crossed FL and emerged in the GoM as a TS, it rather quickly regained strength to hurricane status. Throughout it's crossing it maintained a well defined eye, something we have seen only glimmers of from Isaac. Once in the GoM Katrina underwent concentric eye-wall regeneration and went through two periods of rapid intensification, the first of which occurred over the 24 hour period after entering the GoM and dropped the pressure to ~940 mb, bringing Katrina to a Cat 3 system. Already large and strong, Katrina went from there to then becoming the monster storm it was.

Issac has shown little similarity in system behavior to Katrina, and atmospheric conditions are radically different. However, the forecast track and LA coast projected landfall target surely bring back memories of the forecast track for Katrina that came out over the late August weekend preceding Katrina's landfall.