In the current study, we use idealized, 3D, high-resolution numerical simulations of supercell thunderstorms to evaluate entrainment and its effects during the developing and rotating stages of the storms. Entrainment is quantified using an algorithm that first estimates the sub-grid scale edge of the 3D cloud core, defined with specific condensate and vertical velocity thresholds, and then calculates the mass flux into that core. As entrainment proceeds in time, we track the resulting dilution of the core condensate, and precipitation development (and fallout). Multiple realizations in the same storm environment are created by altering the storm forcing type (heat flux versus warm “bubble”) and the horizontal area over which the forcing is applied.
In comparison to past calculations our group has performed with smaller cumulus clouds, initial results show that the amount of entrainment into the developing thunderstorms is often as much as five times greater, as expected from the stronger updrafts. When the storm forcing is applied over a smaller horizontal area, stronger updrafts result that increase the entrainment. The resulting dilution of the liquid and ice mass within the core is also quicker with the narrower forcing, as a result of the greater entrainment. Analysis of entrainment during the rotating stage of the thunderstorms will also be presented, as will the effects on overall precipitation production, for all cases.