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Andover, KS Tornado Outbreak April 26, 1991

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Andover, KS Tornado Outbreak April 26, 1991 How Did This Occur? A day that will never be forgotten by was mature, very strong, and had Kansas residents, April 26, 1991. A day changing winds with height. Ample moisture, impressive lift, when an F5 tornado ravaged through the incredible instability, and winds town of Andover, KS producing millions The 850 hPa (5,000 ft) map, represen- changing speed and direction with of dollars in damage while killing many tative of conditions just above the height (i.e., vertical wind shear) all and leaving hundreds injured. surface, showed a strong low level jet came together to produce violent that was pumping in moisture ahead tornadoes throughout the Plains, of the cold front and a dry line that including the F5 Andover tornado. were barreling through the region. Near the top of the troposphere at 300 The evening sounding from NWS hPa (30,000 ft), the core of the Norman was a good representation of strongest winds in the jet stream atmospheric conditions near Andover pushed into Kansas, providing around the time of the deadly tornado. exceptionally strong winds and lift. The red and green lines show temperature and humidity. The The 500 hPa (18,000 ft) map showed sounding reported a temperature of 80 the set up in the middle of the with dewpoint of 69 that evening, troposphere. It is clear the axis of the showing that much of the region was in a warm, moist environment system was tilted toward the Monstrous F5 Andover tornado about to rip through a small southeast, which is a sign this system neighborhood. Courtesy of Andover resident Earl Evans. conducive for severe weather. 300hPa 500hPa 850hPa Sounding F-Scale With estimated winds of over 260 mph, the Andover tornado was rated an F5 on the Fujita Scale. Data from weather maps and an atmospheric sounding at 7 pm on April 26. Courtesy of NWS Tulsa, OK Severe Weather Parameters Storm Reports “It seemed like there • Convective Available Potential Energy (CAPE) was no way out that values exceeded 4000 J/kg, which signified that thunderstorms had incredible amounts of energy night, that death was to work with and could easily grow high up towards the tropopause. going to take me” • The wind barbs on the right side of the sounding (Joe Parsley). showed good vertical wind shear in the atmosphere. Winds increasing and changing direction with height were crucial for the Survivor’s Story formation of strong rotating updrafts. • Surface dewpoints well into the 60s with much For Andover resident Joe Parsley, drier air aloft, as seen in the sounding, helped April 26, 1991 will be a day he never create optimal conditions for severe storms with forgets. Parsley was one of the few large hail and tornadoes. lucky mobile home residents who Storm reports from 7 am April 26 to 7 am made it out alive that evening. Not the next day. Courtesy of NWS Tulsa, OK having enough time to seek proper Aftermath and Impacts shelter, he rode out the storm hiding under his truck. As the tornado • 24 deaths total barreled through his neighborhood, • 17 deaths just from the Andover tornado Parsley witnessed what he said to be • Over 300 people injured total “whole roofs coming up and bursting • Over 8,000 people from disaster relief apart in the air, and also cars, services came to help appliances, and other things flying in • More than 250 million dollars in damage air.” After the tornado picked him up throughout the Midwest and pinned him under his truck, he • 102 housing units in Andover destroyed laid there waiting for 45 minutes • 9 facilities destroyed on McConnell Air before he was rescued. Parsley Force Base, including the hospital, library, survived, but spent three months in and enlisted club Andover resident looking through the rubble. Courtesy of NWS Tulsa, OK the hospital with a shattered pelvis. Cody Moore Atmospheric Science University of Louisville .
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