The relationship between tropical easterly waves and surges over the Gulf of California during the North American monsoon

Coastally trapped disturbances, which occur over the Gulf of California and are commonly referred to as gulf surges, are an important mechanism in the transport of low-level moisture into the southwestern United States. To determine whether or not gulf surges develop in association with the passage of tropical easterly waves, as hypothesized in previous studies, standard surface observations and European Centre for Medium-Range Weather Forecasts reanalysis data during the months of July and August over a 14-yr period are examined. Results indicate that tropical easterly wave troughs often cross western Mexico 1-3 days prior to surge onset at Yuma, Arizona, indicating a strong correlation between these two events. This analysis documents yet another mechanism by which the Tropics influences convection in the midlatitudes.