  We address a phenomenon of a confined circumstellar (CS) dense shell and
powerful presupernova emission of SN 2020tlf (type IIP). Modeling the \ha\ line
and the circumstellar interaction implies the CS shell radius of
$\sim$10$^{15}$ cm and the mass of $\sim0.2M_{\odot}$ lost during $\sim$6 yr
prior to the explosion. Spectra and photometry of the supernova after the
explosion do not show apparent signature of the material lost by the
presupernova during its powerful luminosity. This material presumably resided
in the inner zone of the CS shell. We present a hydrodynamic model of the
outcome of a flash with the energy of $5\times10^{48}$ erg in the convective
nuclear burning zone. The model predicts the ejection of outer layers of the
presupernova ($\sim0.1M_{\odot}$) and the luminosity of $10^{40}$ erg s$^{-1}$
during several hundreds days in accord with observations. We propose the
Lighthill mechanism of acoustic waves generation by the turbulence of the
convective nuclear burning zone to account for the phenomenon of a compact CS
shell of supernovae related to the core collapse.
