This study presents the implementation of prognostic aerosols within the Predicted Particle Properties (P3) microphysics scheme to improve the physical consistency of aerosol–cloud–precipitation interactions. Two new prognostic number mixing ratios representing "water-friendly" (CCN) and "ice-friendly" (INP) aerosols are added. Aerosols then evolve dynamically and interact with hydrometeors via nucleation, scavenging, evaporation, and sublimation. The impacts of the modified scheme are investigated using convection-permitting (1-km horizontal grid spacing) simulations of an Arctic mixed-phase cloud case observed on 19–20 January 2026 near Inuvik, Canada. Simulations are compared against "in situ" observations, ground-based radar measurements, and retrievals from the EarthCARE satellite. Results show that the inclusion of prognostic aerosols significantly affects cloud microphysical properties and phase partitioning. The prognostic aerosol simulation produces systematically fewer but larger ice particles, leading to increased reflectivity and enhanced riming. It also results in higher liquid water content and lower ice water content compared to the simulation without prognostic aerosols, thereby favoring the persistence of supercooled liquid layers and improving agreement with retrievals. Sensitivity experiments demonstrate that the choice of ice nucleation parameterization plays a dominant role in controlling the cloud phase. Aerosol-dependent formulations produce lower ice crystal concentrations and more persistent liquid water than the original temperature-dependent scheme, thereby enhancing mixed-phase cloud occurrence. The new prognostic aerosol framework improves the representation of aerosol-cloud indirect effects in P3 and provides a pathway toward more accurate simulations of clouds and precipitation, which are critical for radiative balance and weather prediction in polar regions and elsewhere.