Characteristics of cool-season intermittent precipitation cells in the Pacific Northwest

Orographic enhancement of precipitation occurs over the U.S. West Coast as moisture and low-level flow impinge upon mountainous coastal terrain. While previous work has focused on orographic precipitation from a steady-state process perspective, the intermittency of precipitation cells is less understood. Convective cells embedded within stratiform precipitation are hypothesized to contribute to precipitation intermittency in the region and play an important role in high impact precipitation events in the Pacific Northwest. Building upon previous work whereby a cell tracking algorithm was developed to track individual convective cells, this study seeks to deepen the objective characterization of intermittent precipitation cells in the region. Cell characterization focuses on both the physical structure and dynamics controlling the convective environment. While complementary work takes a Eulerian approach to characterizing the intermittent cells, this study focuses on the cells from a more Lagrangian perspective. Feature-based comparisons of cell characteristics are presented using operational WSR-88D radar data from Portland, Oregon during the cool-season.