Surges of moisture up the Gulf of California, through Rocky Point and into Arizona, help enhance Monsoon storm development.
Gulf Surges happen when clusters of thunderstorms or even dying tropical systems approach the mouth of the Gulf.
The temperature under the cloudy area is cooler than that over Arizona's deserts. So, relatively speaking, the air will be rising over the deserts (hot air rises) much faster than the air under the cool, cloudy area at the mouth of the Gulf. This causes air to begin flowing north through the Gulf of California.
Since the water in the Gulf during the Monsoon is so warm, it evaporates quickly, resulting in extremely humid air. That humid air will fill into the state, usually resulting in big-time rain totals for us in southern Arizona.