High resolution modeling of convective outflow in complex terrain

Up to 80% of the annual precipitation in parts of Sinaloa, Mexico falls during the North American Monsoon (NAM) season. Nearly all precipitation in NW Mexico during the NAM falls in association with convective elements or more organized mesoscale convective systems. Shallow convection typically forms around noon over the high peaks of the Sierra Madre Occidental (SMO). A gradual transition to deep convective towers occurs throughout the afternoon and these elements can organize into MCSs and move off the SMO during the evening, extending over the Gulf of California in some situations. The Sinaloa region is characterized by a narrow coastal plain quickly transitioning into the SMO with peaks over 3000 m, with many steep and complex valleys. Recent research has shown areas of preferential convective initiation and to some extent investigated the role of shear/cold pool interactions on convective organization and propagation.

This presentation will extend past research by examining cold pool interaction with the complex topography and its subsequent role in convective initiation. High resolution simulations with an initial cold bubble over the high terrain shows cold outflow channeled down the steep valleys quickly away from the initial location. Comparisons to cold pool outflow with simpler topographic configurations and different resolutions will be performed. Furthermore, the implications of cold pool channeling on convective longevity and organization will be discussed.