The Generation of a Mesoscale Convective System from Mountain Convection

Abstract

A mesoscale convective system (MCS) that formed just to the east of Denver is investigated with a nonhydrostatic numerical model to determine which processes were important in its initiation. The MCS developed from outflow from previous convective activity in the Rocky Mountains to the west. Model results indicate that this outflow was necessary for the development of the MCS even though a convergence line was already present in the area where the MCS developed. A simulation with a 3-km grid spacing more fully resolves the convective activity in the mountains but the development of the MCS can be simulated with a 6.67-km grid. Cloud effects on solar radiation and ice sedimentation both influence the strength of the outflow from the mountain convection but only the ice sedimentation makes a significant impact on the development of the MCS after its initiation. The frequent convective activity in the Rocky Mountains during the warm season provides outflow that would make MCS generation favorable in this region. Thus, there is a close connection between mountain convective activity and MCS generation. The implications of such a connection are discussed and possible directions of future research are indicated.