Coromuel

Template:Wikify-date The Coromuel wind is a weather phenomenon unique to the La Paz area of the Baja California Peninsula and adjoining Sea of Cortez. Occurring primarily in the late spring and summer, it is a south to south-west wind that typically starts late in the afternoon or early evening and blows throughout the night into the mid-morning. It can be quite strong in Bay of La Paz near the city of La Paz, sometimes thirty knots or more, as attested to in sailing journals such as the Latitude 38 reports[1] and the author's personal experience, but as one travels north the wind becomes less strong and it pretty much dissipates after twenty or thirty miles.

The basic mechanism of the Coromuel winds is fairly clear: The winds are created when the cool marine air from the Pacific side of the peninsula are drawn over the desert to the relatively warmer side of the Sea of Cortez. It only occurs in the La Paz area because this is the only place on the peninsula that does not have a spine of mountains blocking such an air flow. The reason it only occurs at night must have something to do with the hot air over the land rising and blocking the air flow during the day, but the exact mechanism is not clear, at least to me, particularly given the fact that the wind can start very rapidly indeed. The wind canfrom the personal experience of the author, go from dead calm to thirty knots in a half hour or less, and a long time resident of La Paz who lives on a boat and probably does not maintain a Web site speaks of seeing a "wall of dust" corresponding to the onset of the winds approaching behind the city in the late afternoon. I have not seen any reasonable explanation of what the physics of this sudden onset might be.