Wind Damage >> Biggest Tornado Disasters

A downburst cluster itself is made up of several downbursts. A downburst is an area of strong, often damaging wind produced by a convective downdraft with the overall size of the downburst varying from 4 to 6 miles (8 to 10 kilometers). Within the downbursts are microbursts; Biggest Tornado Disasters smaller pockets of more intense wind. 

While not shown in the illustration at right, within the microbursts are even smaller pockets of extreme Biggest Tornado Disasters wind called burst swaths. Burst swaths can range from 50 to 150 yards (45 to 140 meters) long. The damage pattern from burst swaths can often resemble a path of a tornado. 

Due to this nature of the derecho, damage produced by these wind storms is highly variable along its path. Damage surveys following derecho events Biggest Tornado Disasters have shown that within large areas of overall damage are much smaller pockets of intense damage. It is not uncommon for one house to be nearly destroyed while adjacent houses have relatively minor damage. 

Derechos are produced by long-lived thunderstorm complexes that produce bow echoes. NOTEWORTHY EVENTS Many significant derechos (i.e., those that have caused severe damage and/or casualties), Biggest Tornado Disasters have occurred over North America during the last few decades. Most of these affected central and eastern parts of the United States and Canada. 

Linked below are brief summaries of some of these events. The list is not all-inclusive, and additional cases will be added as time permits. Information includes a map of the area affected, Biggest Tornado Disasters a description of the storm's impact and meteorology, and, where available, links to additional information. Holiday weekend events 

The human impact of the following events was enhanced by their occurrence on summer holiday weekends, Biggest Tornado Disasters causing many to be caught out-of-doors during the sudden onset of high winds... July 4, 1969................"The Ohio Fireworks Derecho"....MI, OH, PA, WV July 4, 1977................

"The Independence Day Derecho of 1977"....ND, MN, WI, MI, OH July 4-5, 1980............"The 'More Trees Down' Derecho"....NE, IA, MO, IL, WI, IN, MI, OH, PA, WV, VA, MD Sept. 7, 1998............."The Syracuse Derecho of Labor Day 1998"....NY, PA, VT, MA, NH Biggest Tornado Disasters Sept. 7, 1998.............

"The New York City Derecho of Labor Day 1998"....MI, OH, WV, PA, NJ, NY, CT July 4-5, 1999............"The Boundary Waters-Canadian Derecho"....ND, MN, ON, QB, NH, VT, ME Biggest Tornado Disasters The derechos of mid-July 1995 The mid-July 1995 derechos were noteworthy for both their intensity and range... Series Overview..........

Montana to New England July 12-13, 1995........"The Right Turn Derecho"....MT, ND, MN, WI, MI, ON, OH, PA, WV Biggest Tornado Disasters July 14-15, 1995........"The Ontario / Adirondacks Derecho"....MI, ON, NY, VT, NH, MA, CT, RI Low dewpoint derechos In contrast to most derechos, these events occur in environments of very limited moisture... 

Nov. 20, 1989............."The Mid-Atlantic Low Dewpoint Derecho of November 1989"....PA, NJ, NY, MD, DE Biggest Tornado Disasters May 31, 1994............."The Utah / Wyoming Derecho of May 1994"....UT, WY, ID, CO Serial derechos Three well-documented events that affected parts of the central and eastern United States... April 9, 1991...............

"The West Virginia Derecho of 1991"....AR,TN, MS, AL, KY, IN, OH, WV, VA, MD, PA Biggest Tornado Disasters March 12-13, 1993...."The Storm of the Century Derecho"....FL, Cuba April 19-20, 2011......."The Ozarks / Ohio Valley Derecho of April 2011"....OK, TX, AR, MO, IL, IN, OH, KY, TN, MS, AL 

"Southward bursts" "Southward burst" is a term coined by Porter et al. in a 1955 paper (see reference here) to describe a progressive-type squall line that surges rapidly southward rather than east... Biggest Tornado Disasters May 4-5, 1989............"The Texas Derecho of 1989"....TX, OK, LA May 27-28, 2001......."The People Chaser Derecho"....KS, OK, TX 

Other noteworthy events June 7, 1982.............."The Kansas City Derecho of 1982"....KS, MO, IL July 19, 1983.............."The I-94 Derecho"....ND, MN, IA, WI, MI, IL, IN May 17, 1986............."The Texas Boaters' Derecho".....TX July 28-29, 1986........"The Supercell Transition Derecho"....IA, MO, IL Biggest Tornado Disasters July 7-8, 1991............

"The Southern Great Lakes Derecho of 1991"....SD, IA, MN, WI, MI, IN, OH, ON, NY, PA May 30-31, 1998......."The Southern Great Lakes Derecho of 1998"....MN, IA, WI, MI, ON, NY Biggest Tornado Disasters June 29, 1998............"The Corn Belt Derecho of 1998"....NE, IA, IL, IN, KY July 22, 2003..............

"The Mid-South Derecho of 2003"....AR, TN, MS, AL, GA, SC May 8, 2009..............."The 'Super Derecho' of May 2009"....KS, MO, AR, IL, IN, KY, TN, VA, WV, NC July 10-11, 2011........"The Cross Country Derecho of July 2011"....CO, KS, NE, IA, IL, WI, IN, MI, OH, KY, WV, PA, MD, VA Biggest Tornado Disasters June 29, 2012............

"The Ohio Valley / Mid-Atlantic Derecho of June 2012"....IL, IN, KY, OH, WV, PA, VA, MD, DE, NJ, NC Biggest Tornado Disasters The maps link to a display of all severe weather reports and locations in the Storm Prediction Center data base for the day of the event. 

The records are preliminary and do not include official National Weather Service final storm report information listed in Storm Data; the data also do not include reports from Alaska and Hawaii. The maps do, Biggest Tornado Disasters nevertheless, provide a general idea as to the typical geographical and seasonal distribution of severe wind-producing events in the United States. 

Information on significant derechos that have occurred since 2005 will be added, on a time-permitting basis, to Noteworthy Events. PICTURES AND VIDEOS A video has been prepared by Biggest Tornado Disasters the Atmospheric Environment Service of Canada on the progressive derecho that crossed the Pakwash forest of northwest Ontario on July 18, 1991. 

This video includes camcorder footage of the storm affecting a forested area, post storm aerial views of the forest "blowdown", and Biggest Tornado Disasters interviews with people that experienced the storm. On May 27-28, 2001, a "Southward burst" derecho affected parts of the southern Great Plains from southwest Kansas into central Texas. 

Numerous photographs of the menacing gust front cloud structure associated with the derecho, and videos showing the damaging winds in progress, Biggest Tornado Disasters were taken on that day. A few images from the event may be seen by clicking the hyperlink at the beginning of this paragraph. 

REFERENCES Here is a list of selected of research papers on derechos and the convective systems responsible for their development. In addition to presenting analyses of some well-documented events, Biggest Tornado Disasters these papers describe what is known about the formation and mechanics of derecho-producing convective systems.

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