6. May 25, 1955, 9:26 p.m., F5, Noble and Kay counties, Sumner County in Kansas; eight miles west of Marland, east of Tonkawa, Blackwell, southeast of South Haven, Kan.
7. May 25, 1955, 10 p.m., F5, Kay County in Oklahoma, Sumner and Cowley counties in Kansas; south of Ashton, Kan., Udall Kan., Atlanta, Kan.
8. May 5, 1960, 5 p.m., F5, Pottawatomie, Lincoln, Okfuskee, Creek counties; south of Shawnee, between Paden and Prague, Iron Post, Sapulpa, northeast of Sapulpa.
9. March 26, 1976, 3:28 p.m., F5, Le Flore County; 4 miles east of Bokoshe, Spiro.
10. April 2, 1982, 3:50 p.m., F5, Choctaw and McCurtain counties; south of Speer, near Messer, Hugo Lake, south edge of Broken Bow, four miles southeast of Eagleton.
11. May 3, 1999, 5:26 p.m., F5, Grady, McClain, Cleveland, Oklahoma counties; two miles south, southwest of Amber, far north Newcastle, southwest Oklahoma City, north Moore, south Del City, west Midwest City.
12. May 24, 2011, 3:50 p.m., EF5, (First EF5 in Oklahoma after scale change) Canadian, Kingfisher, Logan counties; four miles west, southwest of Hinton, near Calumet, near El Reno, near Piedmont, near Cashion, four miles northeast of Guthrie.
SOURCE: National Weather Service,
Norman Forecast Office