Late in the evening on April 29, 2012, a fierce hailstorm deposited nearly seven inches of hail on the level near the small town of Idalia, Colorado, a small town 11 miles west of the Colorado-Kansas border and 32 miles north of Interstate 70. Motorists on US-36 west of Idalia were stranded and had to await rescue by snowplows. Roads and fields were buried as if by an off-season blizzard. The ground remained white for several days, despite sunshine and afternoon temperatures from the 70s to low 80s.
THOMAS W. SCHLATTER is a retired meteorologist and volunteer at NOAA's Earth System Research Laboratory in Boulder, Colorado. He is a contributing editor of Weatherwise, and has written the Weather Queries column since 1980.
DAVID L. FLOYD is the Warning Coordination Meteorologist at the National Weather Service office in Goodland, Kansas.