Initial latitudes and field strengths of flux tubes (red diamonds) chosen for flux-tube rise computations, plotted over linear stability diagrams for flux tubes at the middle of the overshoot region, for (panel a), (panel b), (panel c), and (panel d), with differential rotation ΔΩ_⋆ = ΔΩ_⊙. The contour lines denote the growth time in days. The linearly stable regime is shown in white, and the unstable regime is shaded with light grey where the fastest-growing mode is m = 1, and with dark-grey for m = 2. The red diamonds show the initial tube parameters chosen for the numerical simulations, at a growth time of 50 days.