An Analysis of the Development of Persistent Landfalling Atmospheric Rivers along the Western Coastline of North America

Landfalling atmospheric rivers (ARs) are linked to heavy precipitation and extreme flooding, most notably along the western coast of North America. The duration and magnitude of landfalling ARs are correlated to their hydrological impacts on land. Previous work comparing a subset of persistent wintertime (October - March) landfalling ARs to all other landfalling events shows they have distinct moisture and circulation features. Here, we use the Weather Research and Forecasting (WRF) model to simulate the development of a three, well observed, persistent landfalling events at high resolution (4 km) in order to investigate the role of moisture in AR persistence along the coastline. The control simulation compares well against observations, in both the vertical structure and narrow geometry of the AR as it propagates eastward over the basin. We present a comparison of the control simulation to a series of perturbation experiments in which the timing of latent heat release is modified.