We find significant fluctuations of angular momentum within the convective helium shell of a pre-collapse massive star – a core-collapse supernova progenitor – which may facilitate the formation of accretion disks and jets that can explode the star .
The convective flow in our model of an evolved M _ { \mathrm { ZAMS } } = 15 M _ { \odot } star , computed with the sub-sonic hydrodynamic solver MAESTRO , contains entire shells with net angular momentum in different directions .
This phenomenon may have important implications for the late evolutionary stages of massive stars , and for the dynamics of core-collapse .

Key words : stars : massive — supernovae : general