Various disk quantities for certain times t_onset, 1 − t_onset, 4 describing an outburst onset phase. Panels a–c: radial surface density structure Σ and the pressure scale-height H_p during the onset of an outburst, respectively. Panel b: midplane gas temperature T₀ (solid) and the surface temperature T_surf (dashed). The dotted line marks the activation temperature T_active. Panel d: radial mass transport rate Ṁ, where the dotted line corresponds to Ṁ = 0. The deviation from a Keplerian accretion disk is shown in panel e, whereas panel f: gas pressure at the midplane P_gas, 0. Finally, panel g maps the various snapshots in time to the stages during the onset of an outburst. The dashed black line in panels a–f denote the stationary initial model as described in Sect. 3.5.