Major Atmospheric River to Hit Mexico This Week.

Starting December 26, an atmospheric river will enter northwestern Mexico, bringing significant weather changes primarily to Baja California, Sonora, and Chihuahua. This phenomenon, which transports massive amounts of tropical water vapor, is expected to interact with cold fronts to produce a sharp drop in temperatures, heavy rainfall, and potential snow or sleet in mountainous areas. While the most severe effects will be concentrated in the northwest, the combination of this system with polar jet streams and additional cold fronts will bring wind and rain to other parts of the country through the end of December.