  A tidal disruption event (TDE) occurs when a star is destroyed by a
supermassive black hole. Broadband radio spectral observations of TDEs trace
the emission from any outflows or jets that are ejected from the vicinity of
the supermassive black hole. However, radio detections of TDEs are rare, with
less than 20 published to date, and only 11 with multi-epoch broadband
coverage. Here we present the radio detection of the TDE AT2020vwl and our
subsequent radio monitoring campaign of the outflow that was produced, spanning
1.5 years post-optical flare. We tracked the outflow evolution as it expanded
between $10^{16}$ cm to $10^{17}$ cm from the supermassive black hole, deducing
it was non-relativistic and launched quasi-simultaneously with the initial
optical detection through modelling the evolving synchrotron spectra of the
event. We deduce that the outflow is likely to have been launched by material
ejected from stream-stream collisions (more likely), the unbound debris stream,
or an accretion-induced wind or jet from the supermassive black hole (less
likely). AT2020vwl joins a growing number of TDEs with well-characterised
prompt radio emission, with future timely radio observations of TDEs required
to fully understand the mechanism that produces this type of radio emission in
TDEs.
