MAY 4-5, 1989
DERECHO
"The Texas Derecho of 1989"
Figure 1. Evolution of radar echoes (reflectivity images from rain and hail) associated with the May 4-5, 1989 derecho event. Radar images are shown in approximately 2 hourly intervals in Central Daylight Time. (Modified from Smith, 1990)
During Thursday afternoon on May 4th, 1989 an isolated supercell developed over southeastern Colorado and moved southeastward into the Texas panhandle. As the supercell was moving through the Amarillo area (about 5-6 PM CDT) it began evolving into a bow echo (see Fig. 1). This bow echo continued southeastward and grew in scale reaching its maximum size in the area from Dallas/Ft. Worth southward into central Texas. The storm system moved into southwestern Louisiana about 3 AM CDT on May 5th and finally dissipated in southeastern Louisiana about 7 AM CDT.
As the storm system shown in Fig. 1 moved rapidly southeastward across the southern Plains it created a "high end" derecho event (Fig 2). At some locations in northwest Texas the severe derecho winds lasted for 20 to 30 minutes. Measured wind gusts reached 100 mph at the Pantex Plant just east of Amarillo, 75 mph at Brice, and 86 mph at the Childress airport (Fig 2). Over 100 mobile homes were damaged, overturned, or destroyed. Four tractor trailers were blown over and a commercial radio transmitter tower was blown down. Many power lines and poles were also blown down throughout the area. Many buildings were damaged and some barns destroyed. One person was seriously injured in a collapsed barn.
Figure 2. Area affected by the May 4-5, 1989 derecho event (outlined in blue). Curved purple lines represents locations of the "gust front" at three hourly intervals. Measured wind gusts are plotted in mph. "+" symbols indicate the locations of wind damage or estimated wind gusts above severe limits (58 mph or greater). Red dots and paths indicate tornado events.
Although the thunderstorms (radar echoes) associated with the derecho passed south of Oklahoma, wind damage occurred over portions of southwestern Oklahoma since the derecho gust front extended out well to the north of the storms themselves. The primary path of the storms and the derecho continued southeastward across north central and eastern Texas where measured wind gusts reached 78 mph at the Wichita Falls airport, 95 mph at a power plant just north of Graham, 100 mph at a TV station in Ft. Worth, and 83 mph at the Tyler airport (Fig. 2). In this portion of Texas literally thousands of businesses, homes, and mobile homes were damaged with over 100 structures (mostly mobile homes) destroyed. Two people were killed and several dozen were injured. Some of the worst damage occurred in Young, Palo Pinto, Hood, Tarrant, Johnson, and McLennon Counties. Over 250,000 customers lost electrical power in Tarrant County (Ft. Worth metropolitan area).
The derecho continued causing damage to trees and buildings as it crossed southern Louisiana during the early morning hours on May 5th. It finally ended near New Orleans around 7 AM CDT.
In summary, this derecho traveled 900 miles in 15 hours. However, most of its track and the most intense damage occurred across the broad state of Texas. It began in the semi-arid region of the northwestern Texas panhandle and surged southeastward at a speed greater than 60 mph for 700 miles reaching the lush forested region in southeastern Texas in 11 hours. Many thousands of Texans were affected by this intense derecho event and some probably still remember it as the great storm of 1989.
(References......Smith, 1990; Storm Data for May 1989)