Flash flooding not expected this weekend across southern Utah canyon country

The weekend looked workable for canyon country road trips, with the National Weather Service’s Salt Lake City office saying flash flooding was not expected across southern Utah’s major recreation areas for the rest of Friday, Saturday and Sunday. That put a long list of traveler favorites in the clear for the time being: Arches, Bryce Canyon, Canyonlands, Capitol Reef, Glen Canyon National Recreation Area, Grand Staircase-Escalante East and West, Natural Bridges National Monument, Grand Gulch, the San Rafael Swell, Snow Canyon, Red Cliffs and Zion National Park.

The outlook was last issued at 1:08 p.m. MDT on Friday, June 19, and the weather service’s own definition of “Not Expected” means flash flooding was not expected. For anyone trying to decide whether to keep a permit, drive out to a trailhead or commit to a slot-canyon day, that was the kind of short-term green light that mattered. It did not make the region risk-free, but it did suggest the immediate flood threat was low enough to keep a lot of plans intact.

That caveat still mattered most in narrow canyons, washes and low-water routes, where a storm miles away can send water into a drainages system long after the sky overhead looks calm. Zion National Park says summer daytime temperatures regularly exceed 100 degrees Fahrenheit, and that mid-to-late summer monsoons increase the chance of flash floods. The park also warns that all narrow canyons are potentially hazardous, that water can rise within minutes or seconds, and that a flood can come down a canyon in a wall of water 12 feet high or more.

The practical move before entering The Narrows, a wash or any slot canyon was to check the latest forecast again. The National Weather Service says Flash Flood Warnings are issued when flooding is in progress, imminent or highly likely, and are usually posted minutes to hours before onset. In Zion, The Narrows closes when the Virgin River goes above 150 cubic feet per second and when a Flash Flood Warning is in effect.

The reason that caution stays part of every canyon-country weekend is Zion’s own history. On September 14, 2015, the park recorded 0.63 inches of rain during the Keyhole Canyon flood, and the North Fork of the Virgin River jumped from 55 cubic feet per second to 2,630 cubic feet per second in 15 minutes. Seven canyoneers died there. So even with a favorable forecast, the smartest read on southern Utah was simple: keep the trip on, but keep checking the sky, the gauges and the next weather update before dropping into any canyon that can trap you.