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Notable Derechos

Following are a few of the more historic derechos over the past 2 decades.

May 8, 2009 Super Derecho

This was one of the most intense and unusual derechos ever observed. The wind storm produced significant and often continuous damage over a broad swath from the high plains of western Kansas to the foothills of the Appalachians in eastern Kentucky.

Multiple wind gusts in excess of 70 mph (113 km/h) and a few gusts over 90 mph (145 km/h) were measured along its path. In addition, flash flooding was widespread on the northern edge of the system, especially in Missouri.

Car crushed by a fallen tree in Memphis, TN during the Mid-South Derecho of 2003. The Commercial Appeal staff photo by Alan Spearman, used with permission.

But what made the event most unique was the appearance of an unusually strong, long-lived, larger-scale circulation known as a mesoscale convective vortex.

This feature was accompanied by a band of intense surface winds and tornadoes that occurred independent of the severe weather directly associated with the large-scale bow. (May 8, 2009 Super derecho details)

The Mid-South Derecho of 2003

During the early morning of Tuesday, July 22, 2003, a derecho formed over north central Arkansas and moved rapidly east-southeast, reaching northern Alabama by mid-morning.

Although the storm weakened over northern Alabama, it re-developed over northwest Georgia and moved across northern and central Georgia into South Carolina before ending by late afternoon. Many thousands of trees were damaged or blown down. Two people were killed and 11 others were injured, mostly due to trees falling on homes or vehicles.

Between 6 and 7 AM CDT Tuesday, the derecho passed through the Memphis, Tennessee metropolitan area, producing some of the most intense winds during its existence. Numerous homes and buildings were damaged, and at least 20 were destroyed. (Mid-South derecho of 2003 details)

The "People Chaser" Derecho

On Sunday afternoon, May 27th, 2001, isolated supercell thunderstorms, some producing brief tornadoes, formed over western Kansas. As the outflow of cold air from the supercell storms increased, a gust front developed over southwest Kansas and began moving rapidly southeastward.

The thunderstorms associated with the gust front eventually evolved into a bow echo squall line. The southeast-moving bow echo storm system produced a derecho with significant wind damage over a large part of the southern Plains.

The maximum wind gust in Kansas reached 100 mph (161 km/h) near Garden City. In Oklahoma, a maximum wind gust of 94 mph (151 km/h) was measured at Quail Springs Mall in the northwest part of the Oklahoma City metropolitan area; a gust to 93 mph (150 km/h) was recorded in Ardmore, Oklahoma.

A homeowner in Memphis, TN working to extract a large, uprooted oak tree felled by the Mid-South Derecho of 2003. The Commercial Appeal staff photo by Alan Spearman, used with permission.

The maximum gust in Texas was 78 mph (126 km/h) in suburban Fort Worth. In many areas affected by the system, the severe gusts lasted 10 to 20 minutes before subsiding. ("People Chaser" derecho details)

The "Right Turn" Derecho

During the late afternoon of Wednesday, July 12, 1995, thunderstorms formed over southeast Montana and began producing winds that damaged homes and barns and blew over a mobile home. As the storm system moved east across North Dakota, vehicles were overturned and a grain bin was destroyed.

Measured winds reached 70 mph (113 km/h) at Bismarck, ND. As the system approached Fargo, ND during the early morning of July 13th, it became a well-defined bow echo storm with measured winds of 91 mph (146 km/h) at the Fargo airport. Damage was extreme across Minnesota, with over five million trees blown down and many buildings damaged and some destroyed.

Six campers were injured from the falling trees during the pre-dawn hours. Trucks with plows were needed to clear many of the roads, and some areas were without power for a week. Damage totaled well over $30 million in 1995 dollars. (Right Turn" derecho details)

The Ontario-Adirondacks Derecho

On the evening of Friday, July 14, 1995, thunderstorms producing severe weather were occurring over Upper Michigan and adjacent portions of Ontario, Canada near Sault Saint Marie.

By late evening the storms had evolved into a bowing line just northwest of the Mackinac Bridge in Michigan. At 10:17 PM EDT, the thunderstorm gust front hit the bridge and a gust to 90 mph (145 km/h) was measured.

View of the 'People Chaser' derecho storm system near Fort Supply, OK. Photo by Douglas Berry, used with permission.

Sustained winds above 80 mph (129 km/h) continued on the bridge for 10 more minutes.

Thus, began the intense "Ontario-Adirondacks Derecho" that would cause hundreds of millions of dollars' worth of damage, several deaths, and many injuries as it raced southeast from the northern Great Lakes to the Atlantic coast. (Ontario-Adirondacks derecho details.)

The "Storm of the Century" Derecho

On Friday, March 12, 1993, a strong low-pressure system formed in the Gulf of Mexico. This low-pressure system continued to strengthen dramatically and moved northeast to the mid-Atlantic coastal region by Saturday evening, March 13th.

Besides producing a record snowstorm over the eastern United States, this low-pressure system was accompanied by an intense squall line with embedded bow echoes ahead of the system's cold front.

The squall line produced a serial derecho as it swept across the Florida peninsula, Cuba, and adjacent waters. ("Storm of the Century" derecho details)

"The West Virginia Derecho of 1991"

On the morning of Tuesday, April 9, 1991, a bow echo formed over eastern Arkansas and began to produce wind damage. As the day progressed, a serial derecho developed as the original bow echo raced northeast and expanded in scale, while an additional bow echo formed farther north.

Most of these casualties resulted from falling trees, flying debris, and mobile homes being overturned or destroyed.

The most destructive damage extended from western Tennessee through Kentucky and West Virginia into western Maryland and southern Pennsylvania. Winds along this band exceeded 80 to 100 mph (129 to 161 km/h) at some points. Literally thousands of buildings and mobile homes were damaged or destroyed. ("The West Virginia Derecho of 1991" details)

More noteworthy derechos from the Storm Prediction Center.