Cumberland Plateau Tornado Outbreak
November 10, 2002
On November 10th, the ingredients for a major outbreak of tornadoes came together across the Cumberland Plateau region of east Tennessee (topography map). The number and severity of the tornadoes that evening made this outbreak the largest across east Tennessee since the super outbreak of April 3-4, 1974. Numerous supercells (thunderstorms with strong rotation) developed across the region with a total of seven tornadoes (tornado track map) reported across the northern Cumberland Plateau region, six of which occurred in the Morristown County Warning Area. These supercells developed because of the strong winds that increased and changed direction with height. South winds around 45 mph were observed around 5,000 feet, southwest winds around 70 mph were observed around 18,000 feet, and southwest winds around 95 mph were observed around 34,000 feet. This 'wind shear', along with a strong difference between the unseasonably warm temperatures at the surface and colder temperatures aloft, helped to produce a high potential for supercell thunderstorm development and the possibility of strong tornadoes. Because of this potential, the Hazardous Weather Outlook issued Saturday morning mentioned the possibility of tornadoes, while a strongly worded Special Weather Statement issued early Sunday morning described the unfolding dangerous scenario. As thunderstorms began to develop over the region later that afternoon, the Storm Prediction Center issued a 'particularly dangerous situation' tornado watch at 5:50 pm EST for all of east Tennessee.
At 6:18 p.m. EST, the National Weather Service (NWS) in Morristown issued a severe thunderstorm warning for Morgan and Scott Counties. Shortly thereafter at 6:20 p.m. EST, radar reflectivity images began to show some indications of a hook echo, which is a 'classic' tornado signature. Hook echoes on the back edge of storms can indicate that rain is being wrapped around a strong rotation. The storm relative velocity images at this time also indicated developing rotation. Storm relative velocity images show the velocity of the wind (in relation to the radar) with the motion of the storm subtracted out. The green areas on these images indicate wind moving toward the Morristown radar with the red areas indicating wind moving away from the radar. When these two areas are next to each other in a tight couplet, we can infer that there is rotation.
The severe thunderstorm warning for Morgan and Scott Counties was immediately upgraded at 6:26 p.m. EST to a tornado warning for both counties due to these radar indications. A weak tornado was found to have touched down in northern Morgan County just southwest of Rugby around 6:35 p.m. EST. This tornado was rated an F0 on the Fujita intensity scale and had a path length of 1.9 miles and a path width of 50 yards. A number of trees were found down, but no building damage was found.
This same supercell thunderstorm continued moving east-northeast and produced another tornado just north of Elgin in Scott County around 6:40 p.m. EST. This tornado was rated an F1 and was around 4.1 miles in length and 100 yards in width. Radar reflectivity images at 6:43 p.m. EST did not show the 'classic' hook echo signature, but good rotation was seen on the storm relative velocity images. Another tornado touched down from this storm across Highway 63 near Winona around 6:50 p.m. EST. This tornado was also rated an F1 with a path length around 4.2 miles and a path width of 100 yards. Radar reflectivity images at 6:49 p.m. EST showed some signs of the hook echo signature, while strong rotation continued on the storm relative velocity images.
Radar reflectivity loop and storm relative velocity loop of this northern Morgan/Scott County supercell thunderstorm from 6:00 p.m. through 7:15 p.m. EST.
Numerous supercells continued to develop across the northern Cumberland Plateau later in the evening, and another tornado warning was issued for Morgan County at 8:12 p.m. EST. Around 8:30 p.m. EST, a strong tornado touched down just west of Mossy Grove in Morgan County (about 5 miles southeast of Wartburg) and continued east-northeast for about 8.3 miles to the Joyner and Petros communities around 8:40 p.m. The tornado was rated a strong F3 with wind speeds estimated around 175 mph. The path width was estimated to be between 200 and 300 yards. Seven deaths and twenty-eight injuries were reported at Mossy Grove and Joyner with numerous homes receiving substantial damage. Damage photographs from Morgan County
Radar reflectivity images at 8:35 p.m. EST showed some signs of the 'classic' hook echo signature (in the center of the image), while the storm relative velocity images revealed strong rotation in a tight couplet.
This supercell thunderstorm continued moving rapidly to the east and a tornado warning was quickly issued for Anderson County at 8:31 p.m. EST and extended at 8:55 p.m. EST. Another tornado touched down near Briceville in Anderson County around 9:00 p.m. EST and also affected the Medford community a few miles further east. This tornado was rated an F2 and was around 5.5 miles in length and 200 yards in width. Numerous homes with substantial damage were reported with this tornado. The radar data at 9:06 p.m. EST showed the supercell near Medford with some signs of a hook echo and strong rotation.
Radar reflectivity loop and storm relative velocity loop of this southern Morgan/Anderson County supercell thunderstorm from 8:00 p.m. through 9:30 p.m. EST.
Another supercell thunderstorm developed further southwest across the Cumberland Plateau later in the evening. A tornado warning was issued for Bledsoe County at 8:13 p.m. CST (9:13 p.m. EST) based on radar indications of a hook echo and strong rotation. An F1 tornado (with winds estimated around 85 to 90 mph) touched down just west of the intersection of Highways 101 and 285 in northwest Bledsoe County between 8:25 and 8:30 p.m. CST (9:25 and 9:30 p.m. EST). This tornado passed just north of the Bellview community and was found to have traveled around 6.2 miles with a path width of 100 yards.
For information about the Cumberland County tornado, please visit the NWS Nashville office's November 10th storm summary.