These are the rainiest hour and minute in American history
A series of thunderstorms moved into the region, but one in particular unleashed a cloudburst that must have felt like it dumped the entire atmosphere's water content onto one town.
Those who were around Holt, Missouri, on June 22, 1947, experienced a weather event unlike any in the recorded weather history -- of the entire planet!
A series of thunderstorms moved into the region, but one, in particular, unleashed a cloudburst that must have felt like it dumped the entire atmosphere's water content onto one town.
Once the storm had passed, it held a world record for the greatest measured one-hour rainfall -- an incredible 12 inches of rain!
That's a FOOT of rain in one hour, and they had 18 minutes to spare.
Luckily, the deluge was localized. About 28 miles away, Kansas City only received 2.23 inches for the entire day -- still a very wet day, but pales in comparison to Holt's experience.
Many areas in the region received "only" 10-12 inches over the entire month, according to the National Weather Service.
Research meteorologists who studied the storm found quite the unusual setup to produce such an extreme rain event.
A tropical air mass supplied ample moisture — dew points were in the mid-70s as a potent front approached with showers and thunderstorms.
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"An upper level storm system moving across the central plains helped to sustain the thunderstorms as they moved into western Missouri," wrote National Weather Service meteorologists in a recap of the storm set up, "with the interaction of features in the upper atmosphere syncing with thunderstorms in the low and middle levels of the atmosphere to produce a thunderstorm capable of extreme rainfall."
The result: 42 minutes of sheer deluge that left its mark on Holt, Missouri, and the world record books.
How about more than an inch of rain in just a minute?
Typically, Independence Day celebrations are front of mind on July 4, but in 1956 in the town of Unionville, Maryland, perhaps they were a bit distracted by the fireworks going on in the raging thunderstorms overhead.
An intense thunderstorm came by and dropped 2.84 inches of rain in 50 minutes -- a torrential rain in its own right that eventually reached 3.60 inches for the day. Good luck setting off fireworks in that downpour!
But the rain gauge there managed to measure a third of all that rain in one minute!
Rainfall then was tracked on a paper rain gauge chart, and meteorologists were shocked to find the station recorded 1.23 inches between the start and end of the 3:23 p.m. measurement! That’s more than 0.02 inches of rain nearly every second.
The recording rain gauge chart indicates that at chart time 3:23+ the pen was at 2.47 inches on the chart scale and at chart time 3:32- it was 3.70 inches.
(Data from Engelbrecht, H.H. and G.N. Brancato, 1959: "World Record One-Minute Rainfall at Unionville, Maryland." Monthly Weather Review 87(8):303-306. Journal of the American Meteorological Society.)
Researchers, rightly skeptical of such a report, went back and considered more than 13 reasons the measurement could have been an error, ranging from "did a bug get stuck in the clock gears, freezing it in time?" to "could a leaf have closed the opening in the receiver until a buildup of water forced it through the opening?" to "could the pen have become jammed?"
But the thorough investigation found no reason for errors, and the measurement stands as the wettest minute recorded in American history.