Modern diesel injection systems operate in high injection pressures reaching 210 MPa. The combination of high injection velocities and elevated cylinder pressure results in droplet atomization under high Weber numbers, typically We>100, which correspond to the shear and catastrophic breakup regimes. The primary atomization of the liquid jet is modeled using the approach of Huh et al.. The modeling of the secondary atomization is based on a Boundary Layer stripping analysis for the shear atomization regime (80<We<800) and on a combination of Boundary Layer stripping and drop fragmentation analysis for the catastrophic atomization regime (800<We). The drop fragmentation process is predicted from instability considerations on the surface of the liquid drop. A preliminary model evaluation has been performed by comparing the computational results with experimental measurements from isolated drops in shock tube experiments as well as with observations from fully developed diesel sprays.