The mountains of West Virginia have endured floods for eons, but the devastating deluge that occurred a year ago was a truly rare event.

As much as 10 inches of rain fell in a 24-hour period. Water cascaded down hillsides and funneled into populated, narrow river valleys. The “1,000-year flood” killed 23 people, destroyed 1,500 homes and damaged another 2,500. At least $50 million in roads and bridges were washed out. Dozens of schools were damaged, some of which needed to be completely rebuilt.

“The flooding we experienced Thursday and into [Friday] is among the worst in a century for some parts of the state,” said Gov. Earl Ray Tomblin (D), who declared a state of emergency in 44 of West Virginia’s 55 counties, the Capital Weather Gang reported last year.

The rain started on June 23 when thunderstorms bubbled up to the northwest. Hot, high pressure was parked over the central United States, setting up a “ring of fire” thunderstorm pattern that we’ve noted before. What ensued was a prolonged period of “training,” or thunderstorm cells forming one after another over the exact same area.

“Rainfall totals were staggering,” Tom DiLiberto wrote in a National Oceanic and Atmospheric Administration blog about the event. “In Greenbrier County, West Virginia, Maxwelton received 9.67 inches of rain in the 36 hours leading up to June 24. White Sulphur Springs observed 8.29 inches in 24 hours, doubling the previous record for wettest day (4 inches, set in 1890).”

Historic flooding in West Virginia has killed at least 26 people with hundreds more who had to be rescued in the state's worst flooding in more than a century. (Reuters)

Had this occurred in the flat lands it might not have been as catastrophic, but with the rugged topography of West Virginia the water had nowhere else to go but into the hollows, submerging entire towns.

The Elk River rose to 33.4 feet that day, breaking a record set in 1888.

Clendenin, with a population of just over 1,200, was one of the hardest-hit communities. Almost the entire downtown was decimated. Practically every home and business on the town’s main thoroughfare was damaged, including the public library and the post office. The destruction was so widespread the state used inmates from a prison to help clear debris.

Greenbrier County, which was swamped by an astonishing 7 inches of rain in a mere three hours, saw the largest loss of life; 15 people there perished.

The flooding also did severe damage to the famous Greenbrier Resort’s “Old White” golf course, which was scheduled to hold a PGA event the next week. Instead, the resort turned into a makeshift shelter and, according to the Associated Press, nearly 300 people who lost their homes took up residence in Greenbrier rooms.

Contrary to popular belief, a 1,000-year flood does not mean it occurs once every 1,000 years. It actually means that the probability of that much rain falling in a 24-hour time period has a 0.1 percent chance of happening in any given year. In other words, this area does not have to wait another 1,000 years for something like this to occur again. It could happen tomorrow; it’s just that the odds of it occurring are 1 in 1,000.