  Stealth coronal mass ejection (CMEs) are eruptions from the Sun that are not
associated with appreciable low-coronal signatures. Because they often cannot
be linked to a well-defined source region on the Sun, analysis of their initial
magnetic configuration and eruption dynamics is particularly problematic. In
this manuscript, we address this issue by undertaking the first attempt at
predicting the magnetic fields of a stealth CME that erupted in 2020 June from
the Earth-facing Sun. We estimate its source region with the aid of off-limb
observations from a secondary viewpoint and photospheric magnetic field
extrapolations. We then employ the Open Solar Physics Rapid Ensemble
Information (OSPREI) modelling suite to evaluate its early evolution and
forward-model its magnetic fields up to Parker Solar Probe, which detected the
CME in situ at a heliocentric distance of 0.5 AU. We compare our hindcast
prediction with in-situ measurements and a set of flux rope reconstructions,
obtaining encouraging agreement on arrival time, spacecraft crossing location,
and magnetic field profiles. This work represents a first step towards reliable
understanding and forecasting of the magnetic configuration of stealth CMEs and
slow, streamer-blowout events.
