Galloway Flash Flood
November 17, 2003
The above image pair, showing flooding of the Galloway Wash, was captured on October 10, 2003. Odd as it may seem, flash floods are a major threat to those who live in the Arizona desert -- they're the primary cause of loss of life. Winter rains tend to be long and steady, but summer monsoon storms come quickly and tend to be localized. With relatively little vegetation, most of the storm runoff occurs in a short period of time.
On this morning, there was 3 cm of rain (1.2") in about an hour, which led to the closing of the road pictured above (it was closed about two hours). The average annual rainfall in this area (near Cave Creek, Arizona) is about 30 cm (12"). The last vehicle to traverse the wash was a large pick-up truck that lost traction in the back wheels and was nearly washed downstream. Prudent drivers never cross washes under these conditions.