SALT LAKE CITY -- Monday's flash flooding was the most deadly weather disaster to ever occur in Utah. Twelve people are confirmed dead and a child is still missing after flash flooding in Hildale, and another six are confirmed dead with another individual missing after flooding in Zion National Park.
Prior to Monday, that dubious distinction would have fallen to a pair of avalanches in Alta in 1881 and 1885. In each case, 15 people were killed.
The most deadly flooding in Utah happened in 1923 in Farmington and in 1965 in Sheep Creek Canyon near Flaming Gorge.
Utah has also experienced days where more people died in a sudden, violent events. The worst single day's disaster happened in the town of Scofield.
They lost at least 200 people to a mine explosion on May 1, 1900. That's one of many terrible days for Utah miners. In fact, when the devastating avalanches hit Alta, it was a Silver Mining boom town, not a ski resort.
Flash flooding is less understood by the general public than other weather disasters like hurricanes, tornadoes and lightning, because it happens in remote places with sudden force and then disappears into the tributary system of the area.
The US Geological Survey measures the power of stream flows through much of the United States, showing the largest river near the flash flooding experienced a massive spike in volume at the time of these floods.
The East Fork of the Virgin river, flowing at 39 cubic feet per second through the day on Monday, rose to 2,630 cubic feet per second in the span of a half and hour.