If you were one of the cars that crossed the border at Lukeville, AZ. on July 12, 2011, you witnessed quite a flood! It all came down within 90 mins. and the 2" of rain made for some tough driving conditions, not to mention some of the buildings that were flooded with water. It's reported that storm debris trapped against new wire mesh fencing contributed to the deluge.
For more details check out this article.