September 29, 2014

Death in the Narrows

Radar over Zion National Park

Over the weekend I screen grabbed this image of intense precipitation over Zion National Park. The line of thunderstorms and accompanying downpours had remained almost stationary for 5+ hours. For Zion that meant intense, dangerous flooding.

If you're unfamiliar with Zion National Park, the main canyon is formed by the Virgin River whose headwaters begin high in the Dixie National Forest. The North Fork of the Virgin River carved a deep narrow gorge through Navajo Sandstone forming Zion Canyon. At the north end of Zion Canyon is The Narrows, a miles long stretch of river where the sandstone walls are, for significant stretches, over 1,500 feet deep and little more than 20 ft across.

So dangerous is the potential for flash flooding, the Park Service closes The Narrows anytime the river's flow exceeds 150 Cubic Feet per Second (CFS). The day I screen grabbed this image, the river hit a peak flow rate of 4,020 CFS. As the USGS image shows here:

USGS Virgin River Gage Height

the river rose to over 14 ft, nearly double it's normal height. Within the tight confines of The Narrows, the flow rate and height would've been exponentially greater. Also note in the image, a flash flood event earlier in September. That day, Zion received its 7th highest single-day rain event in 86 years.

The Narrows is a quintessential Zion National Park hike and, on my upcoming trip I plan to spend a good time exploring it photographically. Monitoring the weather and respecting posted closures, even when the weather may appear benign, is essential. The morning of my screen grab, a Los Angeles duo ignored warning signs and entered The Narrows. The flow rate at the time was only 46 CFS. Within a few hours the flow rate grew nearly 100X. Caught in a raging onslaught, the hikers were able to climb to higher ground but remained stranded for hours. One decided to go for help. Park Rangers were unable, due to the high flow rate, to enter the canyon until the next morning. They discovered the second hiker, dead, presumably drowned.

Hopefully, the story speaks for itself.

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There is nothing worse than a sharp image of a fuzzy concept.

Ansel Adams

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