Damage Survey of the Mayfield, KY Tornado: 10 December 2021 Timothy P. Marshall 1 , Zachary B. Wienhoff 1 , Brian E. Smith 2 , and Christine L. Wielgos 2 1 Haag Engineering Company 2 NOAA/NWS 1. INTRODUCTION On December 10, 2021, a tornado outbreak occurred in the southern U.S. with more than 70 tornadoes reported. The worst hit areas were northeast Arkansas, western Tennessee, western Kentucky, and southern Illinois. This paper will concentrate on the damage in western Kentucky, particularly the towns of Mayfield and Dawson Springs where the most severe damage occurred. A detailed damage survey was conducted in the days following this event and the National Weather Service rated this tornado EF 4 on the Enhanced Fujita (EF) Scale. Various degrees of damage (DoD) were assigned to different damage indicators (DIs) in accordance with the 2006 EF- scale (WERC, 2006). The EF-scale was adopted by the NWS in 2007 and is utilized to rate the severity of tornado damage. The NWS utilizes the damage assessment toolkit (DAT) to record and plot specific locations of the damage. Their mission includes determining the path length, path width, and most intense damage for each tornado. Currently, the EF-scale is being updated and developed into a standard as a joint project by the American Society of Civil Engineers (ASCE), Structural Engineers Institute (SEI) and the American Meteorological Society (AMS). Additions to the EF-scale will include explanations of typical, stronger than typical, and weaker than typical resistance levels for each DI. The number of DoDs will be expanded, and the estimated failure wind speeds will be adjusted accordingly. There also will be a commentary and additional DoD photographs for each DI. The standard is expected to be published in the next few years. The tornado which struck Mayfield and Dawson Springs, Kentucky occurred at night and was a large wedge-type. Refer to Figure 1. _________ *Corresponding author address: Timothy P. Marshall, Haag Engineering Co., 4949 W. Royal Lane, Irving, TX 75063. Email: timpmarshall@cs.com Fig. 1. Nighttime wedge tornado illuminated by lightning between Bremen and Sacramento, KY. Image by Eddie Knight. 2. TRACK OVERVIEW The tornado that traveled through Mayfield and Dawson Springs, Kentucky initially developed in extreme northwest Tennessee, in Obion County, around 2049 UTC (8:49 pm CST), about 3.4 km (2.12 mi) south of the Kentucky state line. The tornado then continued through eleven counties in western Kentucky ending around 2345 UTC (11:45 pm CST) at Rough River Dam State Park in Grayson County, Kentucky. The total path length of this tornado was 267 km (165.7 mi) with a maximum path width of 1.8 km (1.13 mi). Unfortunately, 57 people lost their lives from this tornado and more than 500 people were injured. This long-track tornado was part of a family of tornadoes produced by a supercell that developed near Jonesboro, AR and ended near the Kentucky- Ohio state line. The supercell which produced this family of tornadoes has been dubbed “The Quad State Tornadic Supercell” as it traveled through portions of four states. The storm lasted more than 11 hours and traveled about 966 km (600 mi). The storm had an average forward speed of 27 m/s (60 mph). Refer to Figure 2.