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A ''derecho'' (, from es, derecho, link=no , 'straight') is a widespread, long-lived, straight-line
wind storm A storm is any disturbed state of the natural environment or the atmosphere of an astronomical body. It may be marked by significant disruptions to normal conditions such as strong wind, tornadoes, hail, thunder and lightning (a thunderstorm), ...
that is associated with a fast-moving group of
severe thunderstorm A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are somet ...
s known as a
mesoscale convective system A mesoscale convective system (MCS) is a complex of thunderstorms that becomes organized on a scale larger than the individual thunderstorms but smaller than extratropical cyclones, and normally persists for several hours or more. A mesoscale con ...
. Derechos can cause hurricanic and tornadic-force winds, heavy rains, and flash floods. In many cases, convection-induced winds take on a
bow echo A bow echo is the characteristic radar return from a mesoscale convective system that is shaped like an archer's bow. These systems can produce severe straight-line winds and occasionally tornadoes, causing major damage. They can also become de ...
(backward "C") form of
squall line A squall line, or more accurately a quasi-linear convective system (QLCS), is a line of thunderstorms, often forming along or ahead of a cold front. In the early 20th century, the term was used as a synonym for cold front (which often are accom ...
, often forming beneath an area of diverging upper tropospheric winds, and in a region of both rich low-level moisture and warm-air advection. Derechos move rapidly in the direction of movement of their associated storms, similar to an
outflow boundary An outflow boundary, also known as a gust front, is a storm-scale or mesoscale boundary separating thunderstorm-cooled air ( outflow) from the surrounding air; similar in effect to a cold front, with passage marked by a wind shift and usually ...
(gust front), except that the wind remains sustained for a greater period of time (often increasing in strength after onset), and may exceed
hurricane-force The Beaufort scale is an empirical measure that relates wind speed to observed conditions at sea or on land. Its full name is the Beaufort wind force scale. History The scale was devised in 1805 by the Irish hydrographer Francis Beaufo ...
. A derecho-producing convective system may remain active for many hours and, occasionally, over multiple days. A warm-weather phenomenon, derechos occur mostly in summer, especially during June, July, and August in the Northern Hemisphere (or March, April, and May in the Southern Hemisphere), within areas of moderately strong
instability In numerous fields of study, the component of instability within a system is generally characterized by some of the outputs or internal states growing without bounds. Not all systems that are not stable are unstable; systems can also be mar ...
and moderately strong vertical
wind shear Wind shear (or windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizont ...
. However, derechos may occur at any time of the year, and can occur as frequently at night as during the day. Various studies since the 1980s have shed light on the physical processes responsible for the production of widespread damaging winds by thunderstorms. In addition, it has become apparent that the most damaging derechos are associated with particular types of mesoscale convective systems that are self-perpetuating (meaning that the convective systems are not strongly dependent on the larger-scale meteorological processes such as those associated with blizzard-producing winter storms and strong cold fronts). In addition, the term "derecho" sometimes is misapplied to convectively generated wind events that are not particularly well-organized or long-lasting. For these reasons, a more precise, physically based definition of "derecho" has been introduced within the meteorological community.


Etymology

''Derecho'' comes from the Spanish adjective for "straight" (or "direct"), in contrast with a ''
tornado A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, altho ...
'' which is a "twisted" wind. The word was first used in the ''American Meteorological Journal'' in 1888 by
Gustavus Detlef Hinrichs Gustavus Detlef Hinrichs (2 December 1836 – 14 February 1923) was a chemist and natural philosopher most widely known for his findings on periodic laws within the chemical elements. Life Hinrichs was born in 1836 in Lunden in the Duchy of Hol ...
in a paper describing the phenomenon and based on a significant derecho event that crossed
Iowa Iowa () is a state in the Midwestern region of the United States, bordered by the Mississippi River to the east and the Missouri River and Big Sioux River to the west. It is bordered by six states: Wisconsin to the northeast, Illinois to th ...
on 31 July 1877.


Development

Organized areas of
thunderstorm A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are some ...
activity reinforce pre-existing frontal zones, and can outrun
cold front A cold front is the leading edge of a cooler mass of air at ground level that replaces a warmer mass of air and lies within a pronounced surface trough of low pressure. It often forms behind an extratropical cyclone (to the west in the Northern ...
s. The resultant
mesoscale convective system A mesoscale convective system (MCS) is a complex of thunderstorms that becomes organized on a scale larger than the individual thunderstorms but smaller than extratropical cyclones, and normally persists for several hours or more. A mesoscale con ...
(MCS) often forms at the point of the strongest divergence of the upper-level flow, and new storm cells are developed in the area with the greatest low-level inflow. The convection tends to move east or toward the equator, roughly parallel to low-level thickness lines and usually somewhat to the right of the mean tropospheric flow. When the convection is strongly linear or slightly curved, the MCS is called a squall line, with the strongest winds typically occurring just behind the leading edge of the significant wind shift and pressure rise. Classic derechos occur with squall lines that contain bow- or spearhead-shaped features as seen by
weather radar Weather radar, also called weather surveillance radar (WSR) and Doppler weather radar, is a type of radar used to locate precipitation, calculate its motion, and estimate its type (rain, snow, hail etc.). Modern weather radars are mostly pulse- ...
that are known as ''
bow echo A bow echo is the characteristic radar return from a mesoscale convective system that is shaped like an archer's bow. These systems can produce severe straight-line winds and occasionally tornadoes, causing major damage. They can also become de ...
es'' or ''spearhead echoes''. Squall lines typically "bow out" due to the formation of a mesoscale
high-pressure system A high-pressure area, high, or anticyclone, is an area near the surface of a planet where the atmospheric pressure is greater than the pressure in the surrounding regions. Highs are middle-scale meteorological features that result from interpl ...
which forms within the stratiform rain area behind the initial convective line. This high-pressure area is formed due to strong descending air currents behind the squall line, and could come in the form of a
downburst In meteorology, a downburst is a strong downward and outward gushing wind system that emanates from a point source above and blows radially, that is, in straight lines in all directions from the area of impact at surface level. Capable of pro ...
.Parke, Peter S. and Norvan J. Larson (2005)
Boundary Waters Windstorm.
National Weather Service The National Weather Service (NWS) is an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the ...
Forecast Office, Duluth, MN. Retrieved on 2008-07-30.
The size of the bow may vary, and the storms associated with the bow may die and redevelop. During the cool season within the Northern Hemisphere, derechos generally develop within a pattern of mid-tropospheric southwesterly winds, in an environment of low to moderate atmospheric instability (caused by relative warmth and moisture near ground level, with cooler air aloft, as measured by
convective available potential energy In meteorology, convective available potential energy (commonly abbreviated as CAPE), is the integrated amount of work that the upward (positive) buoyancy force would perform on a given mass of air (called an air parcel) if it rose vertically thro ...
), and high values of vertical wind shear ( within the lowest of the atmosphere). Warm season derechos in the Northern Hemisphere most often form in west to northwesterly flow at mid-levels of the
troposphere The troposphere is the first and lowest layer of the atmosphere of the Earth, and contains 75% of the total mass of the planetary atmosphere, 99% of the total mass of water vapour and aerosols, and is where most weather phenomena occur. From ...
, with moderate to high levels of thermodynamic instability. As previously mentioned, derechos favor environments of low-level warm advection and significant low-level moisture.


Classification and criteria

A common definition is a thunderstorm complex that produces a damaging wind swath of at least , featuring a concentrated area of convectively-induced wind gusts exceeding . According to the
National Weather Service The National Weather Service (NWS) is an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the ...
(NWS) criterion, a derecho is classified as a band of storms that have winds of at least along the entire span of the storm front, maintained over a time span of at least six hours. Some studies add a requirement that no more than two or three hours separate any two successive wind reports. A more recent, more physically based definition of "derecho" proposes that the term be reserved for use with convective systems that not only contain unique radar-observed features such as bow echoes and
mesovortices A mesovortex is a small-scale rotational feature found in a convective storm, such as a quasi-linear convective system (QLCS, i.e. squall line), a supercell, or the eyewall of a tropical cyclone. Mesovortices range in diameter from tens of miles to ...
, but also for events that produce damage swaths at least 100 km (60 miles) wide and 650 km (400 miles) long. A great visual example of a derecho was made available b
time-lapse imagery from satellites
operated by the National Oceanic and Atmospheric Association, which clearly recorded the outer boundary layer of a derecho and the intensity of associated lightning strikes quickly moving eastward in Midwestern states on 10 August 2020. In order to be classified as a derecho, a wind storm must meet the following criteria * Wind damage swath extending for more than * Wind gusts of at least along most of its length * Several, well-separated or greater gusts Four types of derechos are generally recognized: * Serial derecho – This type of derecho is usually associated with a very deep low. ** Single-bow – A very large
bow echo A bow echo is the characteristic radar return from a mesoscale convective system that is shaped like an archer's bow. These systems can produce severe straight-line winds and occasionally tornadoes, causing major damage. They can also become de ...
around or upwards of long. This type of serial derecho is less common than the multi-bow kind. An example of a single-bow serial derecho is the derecho that occurred in association with the
October 2010 North American storm complex The October 2010 North American storm complex is the name given to a historic extratropical cyclone that impacted North America. The massive storm complex caused a wide range of weather events including a major serial derecho stretching from the ...
. ** Multi-bow – Multiple bow derechos are embedded in a large squall line typically around long. One example of a multi-bow serial derecho is a derecho that occurred during the
1993 Storm of the Century The 1993 Storm of the Century (also known as the 93 Superstorm, The No Name Storm, or the Great Blizzard of '93/1993) was a cyclonic storm that formed over the Gulf of Mexico on March 12, 1993. The cold weather, heavy snowfall, high winds and s ...
in
Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...
. Because of embedded
supercell A supercell is a thunderstorm characterized by the presence of a mesocyclone: a deep, persistently rotating updraft. Due to this, these storms are sometimes referred to as rotating thunderstorms. Of the four classifications of thunderstorms ( ...
s,
tornado A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, altho ...
es can spin out of these types of derechos. This is a much more common type of serial derecho than the single-bow kind. Multi-bow serial derechos can be associated with line echo wave patterns (LEWPs) on weather radar. * Progressive derecho – A line of thunderstorms take the bow-shape and may travel for hundreds of miles along stationary fronts. Examples of this include " Hurricane Elvis" in 2003 and the
Boundary Waters-Canadian Derecho Boundary or Boundaries may refer to: * Border, in political geography Entertainment * ''Boundaries'' (2016 film), a 2016 Canadian film * ''Boundaries'' (2018 film), a 2018 American-Canadian road trip film *Boundary (cricket), the edge of the pla ...
of 4–5 July 1999. Tornado formation is less common in a progressive than serial type. * Hybrid derecho – A derecho with characteristics of both a serial and progressive derecho. Similar to serial derechos and progressive derechos, these types of derechos are associated with a deep low, but are relatively small in size. An example is the
Late-May 1998 tornado outbreak and derecho The Late-May 1998 tornado outbreak and derecho was a historic tornado outbreak and derecho that began on the afternoon of May 30 and extended throughout May 31, 1998, across a large portion of the northern half of the United States and southern On ...
that moved through the central Northern Plains and the Southern Great Lakes on 30–31 May 1998. * Low dewpoint derecho – A derecho that occurs in an environment of comparatively limited low-level moisture, with appreciable moisture confined to the mid-levels of the atmosphere. Such derechos most often occur between late fall and early spring in association with strong low-pressure systems. Low
dew point The dew point is the temperature to which air must be cooled to become saturated with water vapor, assuming constant air pressure and water content. When cooled below the dew point, moisture capacity is reduced and airborne water vapor will cond ...
derechos are essentially organized bands of successive, dry downbursts. The Utah-Wyoming derecho of 31 May 1994 was an event of this type. It produced a wind gust at Provo, Utah, where sixteen people were injured, and removed part of the roof of the Saltair Pavilion on the Great Salt Lake. Surface dew points along the path of the derecho were about .


Characteristics

Winds in a derecho can be enhanced by downburst clusters embedded inside the storm. These straight-line winds may exceed , reaching in past events. Tornadoes sometimes form within derecho events, although such events are often difficult to confirm due to the additional damage caused by straight-line winds in the immediate area. With the average tornado in the United States and Canada rating in the low end of the F/ EF1 classification at peak winds and most or all of the rest of the world even lower, derechos tend to deliver the vast majority of extreme wind conditions over much of the territory in which they occur. Datasets compiled by the United States
National Weather Service The National Weather Service (NWS) is an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the ...
and other organizations show that a large swath of the north-central United States, and presumably at least the adjacent sections of Canada and much of the surface of the Great Lakes, can expect winds from over a significant area at least once in any 50-year period, including both
convective Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the convec ...
events and extra-tropical cyclones and other events deriving power from
baroclinic In fluid dynamics, the baroclinity (often called baroclinicity) of a stratified fluid is a measure of how misaligned the gradient of pressure is from the gradient of density in a fluid. In meteorology a baroclinic flow is one in which the densi ...
sources. Only in 40 to 65 percent or so of the United States resting on the coast of the Atlantic basin, and a fraction of the Everglades, are derechos surpassed in this respect — by landfalling
hurricanes A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...
, which at their worst may have winds as severe as EF3 tornadoes. Certain derecho situations are the most common instances of severe weather outbreaks which may become ''less'' favorable to tornado production as they become more violent; the height of 30–31 May 1998 upper Middle West-Canada-New York State derecho and the latter stages of significant tornado and severe weather outbreaks in 2003 and 2004 are only three examples of this. Some upper-air measurements used for severe-weather forecasting may reflect this point of diminishing return for tornado formation, and the mentioned three situations were instances during which the rare Particularly Dangerous Situation
severe thunderstorm A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are somet ...
variety of severe weather watches were issued from the
Storm Prediction Center The Storm Prediction Center (SPC) is a US government agency that is part of the National Centers for Environmental Prediction (NCEP), operating under the control of the National Weather Service (NWS), which in turn is part of the National Oceani ...
of the U.S. National Oceanic & Atmospheric Administration. Some derechos develop a radar signature resembling that of a
hurricane A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...
in the low levels. They may have a central '' eye'' free of precipitation, with a minimum central pressure and surrounding bands of strong convection, but are really associated with an MCS developing multiple squall lines, and are not tropical in nature. These storms have a warm core, like other mesoscale convective systems. One such derecho occurred across the Midwestern U.S. on 21 July 2003. An area of convection developed across eastern
Iowa Iowa () is a state in the Midwestern region of the United States, bordered by the Mississippi River to the east and the Missouri River and Big Sioux River to the west. It is bordered by six states: Wisconsin to the northeast, Illinois to th ...
near a weak stationary/warm front and ultimately matured, taking on the shape of a wavy squall line across western
Ohio Ohio () is a state in the Midwestern region of the United States. Of the fifty U.S. states, it is the 34th-largest by area, and with a population of nearly 11.8 million, is the seventh-most populous and tenth-most densely populated. The sta ...
and southern
Indiana Indiana () is a U.S. state in the Midwestern United States. It is the 38th-largest by area and the 17th-most populous of the 50 States. Its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th s ...
. The system re-intensified after leaving the Ohio Valley, starting to form a large hook, with occasional hook echoes appearing along its eastern side. A surface low pressure center formed and became more impressive later in the day. Another example is the May 2009 Southern Midwest derecho.


Location

Derechos in North America form predominantly from April to August, peaking in frequency from May into July. During this time of year, derechos are mostly found in the
Midwestern United States The Midwestern United States, also referred to as the Midwest or the American Midwest, is one of four census regions of the United States Census Bureau (also known as "Region 2"). It occupies the northern central part of the United States. I ...
and the U.S. Interior Highlands most commonly from Oklahoma and across the
Ohio Valley The Ohio River is a long river in the United States. It is located at the boundary of the Midwestern and Southern United States, flowing southwesterly from western Pennsylvania to its mouth on the Mississippi River at the southern tip of Illino ...
. During mid-summer when a hot and muggy
air mass In meteorology, an air mass is a volume of air defined by its temperature and humidity. Air masses cover many hundreds or thousands of square miles, and adapt to the characteristics of the surface below them. They are classified according to l ...
covers the north-central U.S., they will often develop farther north into
Manitoba , image_map = Manitoba in Canada 2.svg , map_alt = Map showing Manitoba's location in the centre of Southern Canada , Label_map = yes , coordinates = , capital = Winn ...
or Northwestern Ontario, sometimes well north of the Canada–US border.
North Dakota North Dakota () is a U.S. state in the Upper Midwest, named after the indigenous Dakota Sioux. North Dakota is bordered by the Canadian provinces of Saskatchewan and Manitoba to the north and by the U.S. states of Minnesota to the east, So ...
,
Minnesota Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over to ...
, and upper
Michigan Michigan () is a U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest, upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the List of U.S. states and ...
are also vulnerable to derecho storms when such conditions are in place. They often occur along stationary fronts on the northern periphery of where the most intense heat and humidity bubble exists. Late-year derechos are normally confined to
Texas Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by ...
and the Deep South, although a late-summer derecho struck upper parts of the
New York State New York, officially the State of New York, is a state in the Northeastern United States. It is often called New York State to distinguish it from its largest city, New York City. With a total area of , New York is the 27th-largest U.S. stat ...
area after midnight on 7 September 1998. Warm season derechos have greater instability than their cold season counterpart, while cool season derechos have greater shear than their warm season counterpart. Although these storms most commonly occur in North America, derechos can occur elsewhere in the world, with a few areas relatively frequently. Outside North America, they sometimes are called by different names. For example, in
Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...
and parts of Eastern India, a type of storm known as "Kalbaisakhi" or " Nor'westers" may be a progressive derecho. One such event occurred on 10 July 2002 in Germany: a serial derecho killed eight people and injured 39 near Berlin. Derechos occur in southeastern South America (particularly Argentina and southern Brazil) and South Africa as well, and on rarer occasions, close to or north of the 60th parallel in northern Canada. Primarily a
mid-latitudes The middle latitudes (also called the mid-latitudes, sometimes midlatitudes, or moderate latitudes) are a spatial region on Earth located between the Tropic of Cancer (latitudes 23°26'22") to the Arctic Circle (66°33'39"), and Tropic of Caprico ...
phenomenon, derechos do occur in the Amazon Basin of Brazil. On 8 August 2010, a derecho struck Estonia and tore off the tower of Väike-Maarja Church. Derechos are occasionally observed in China. File:Väike-Maarja kirik august2010-1.JPG, Damage to the
Väike-Maarja Church Väike-Maarja Church is a church in Väike-Maarja in Lääne-Viru County, Estonia. Constructed in 1346, Väike-Maarja Church has three nave-halls in Gothic architectural style and was initially built as a fortress church. The church's organ was ...
in Estonia after the derecho hit on 8 August 2010 File:Bwca derecho.jpg, Trees felled by downbursts in the Boundary Waters – Canadian derecho of 1999 File:June 2012 North American derecho - Mount Solon, Va.JPG, Barn in Mount Solon, Virginia, destroyed by
June 2012 North American derecho The June 2012 Mid-Atlantic and Midwest derecho was one of the deadliest and most destructive fast-moving severe thunderstorm complexes in North American history. The progressive derecho tracked across a large section of the Midwestern United Sta ...


Damage risk

Since derechos occur during warm months and often in places with cold winter climates, people who are most at risk are those involved in outdoor activities. Campers, hikers, and motorists are most at risk because of falling trees toppled over by straight-line winds. Wide swaths of forest have been felled by such storms. People who live in mobile homes are also at risk; mobile homes that are not anchored to the ground may be overturned from the high winds. Across the United States, Michigan and New York have incurred many of the fatalities from derechos. Prior to Hurricane Katrina, the death tolls from derechos and hurricanes were comparable for the United States. Derechos may also severely damage an urban area's electrical distribution system, especially if these services are routed above ground. The derecho that struck Chicago, Illinois on 11 July 2011 left more than 860,000 people without electricity. The
June 2012 North American derecho The June 2012 Mid-Atlantic and Midwest derecho was one of the deadliest and most destructive fast-moving severe thunderstorm complexes in North American history. The progressive derecho tracked across a large section of the Midwestern United Sta ...
took out electrical power to more than 3.7 million customers starting in the Midwestern United States, across the central Appalachians, into the Mid-Atlantic States during a
heat wave A heat wave, or heatwave, is a period of excessively hot weather, which may be accompanied by high humidity, especially in oceanic climate countries. While definitions vary, a heat wave is usually measured relative to the usual climate in the ...
. The
August 2020 Midwest Derecho The August 2020 Midwest derecho was a powerful derecho affecting the Midwestern United States on August 10–11, 2020, primarily eastern Nebraska, Iowa, Illinois, Wisconsin, and Indiana. It caused high winds and spawned an outbreak of weak torn ...
delivered a maximum measured wind speed of , with damage-estimated speeds as high as in the Cedar Rapids, Iowa area. The storm was referred to as one of the largest "land-based hurricanes" in recorded history spawning 17 confirmed tornadoes across Wisconsin, Illinois, and Indiana. Ten million acres of crops were damaged or destroyed, accounting for roughly a third of the state of Iowa's agricultural area. Over a million homes across the Midwest were without basic services such as water and electricity. Iowa Governor Reynolds requested $4 billion in federal aid to assist in the recovery efforts. Winds were confirmed as having stirred up in Colorado and Nebraska, and then proceeded in force crossing 5 states including Iowa, Minnesota, Illinois, Indiana, and Ohio leaving destruction in excess of $7.5 billion in estimated damages. A derecho in eastern Ontario and western Quebec killed 10 people and caused $875 million property damage 21 May 2022, the sixth largest "insured loss event" in Canadian history.Insurance Bureau of Canada, quoted in CTV News, 15 June 2022. https://ottawa.ctvnews.ca/may-21-storm-ranked-6th-most-expensive-natural-disaster-in-canadian-history-ibc-1.5948666 Destruction of utility poles deprived some rural communities of telephone and electricity services for a week or longer.


Aviation

Derechos can be hazardous to aviation due to embedded microbursts, downbursts, and downburst clusters. In addition, the powerful updrafts and high cloud tops can cause for dangerous conditions. Their sheer size also makes them very difficult to navigate around.


See also

*
Convective storm detection Convective storm detection is the meteorological observation, and short-term prediction, of deep moist convection (DMC). DMC describes atmospheric conditions producing single or clusters of large vertical extension clouds ranging from cumulus co ...
*
Extreme weather Extreme weather or extreme climate events includes unexpected, unusual, severe, or unseasonal weather; weather at the extremes of the historical distribution—the range that has been seen in the past. Often, extreme events are based on a loca ...
*
Mesocyclone A mesocyclone is a meso-gamma mesoscale (or storm scale) region of rotation (vortex), typically around in diameter, most often noticed on radar within thunderstorms. In the northern hemisphere it is usually located in the right rear flank (back ...
*
Mesoscale convective vortex A mesovortex is a small-scale rotational feature found in a convective storm, such as a quasi-linear convective system (QLCS, i.e. squall line), a supercell, or the eyewall of a tropical cyclone. Mesovortices range in diameter from tens of miles to ...
(MCV) *
Mesovortex A mesovortex is a small-scale rotational feature found in a convective storm, such as a quasi-linear convective system (QLCS, i.e. squall line), a supercell, or the eyewall of a tropical cyclone. Mesovortices range in diameter from tens of miles ...
* Microburst *
List of derecho events The following is a list of derecho events. North America Europe South America Asia See also * Bow echo * Line echo wave pattern * List of deadliest Storm Prediction Center days by outlook risk level * List of microbursts * L ...


References


Further reading

* Ashley, Walker S., et al. (2004).
Derecho Families
. ''Proceedings of the 22nd Conference on Severe Local Storms'',
American Meteorological Society The American Meteorological Society (AMS) is the premier scientific and professional organization in the United States promoting and disseminating information about the atmospheric, oceanic, and hydrologic sciences. Its mission is to advance th ...
, Hyannis, Massachusetts. * * * * * * * * * * *


External links

{{Commons category
Facts about derechos
(Storm Prediction Center's "About Derechos" web page; Stephen Corfidi with Robert Johns and Jeffry Evans)

(
University of Nebraska at Lincoln A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States, the ...
)
What is a derecho?
(Meteorologist Jeff Haby's education page)
Derecho Hazards in the United States
(Walker Ashley)
Origin of the term "Derecho" as a Severe Weather Event
(Meteorologist Robert Johns)
A Mediterranean derecho: Catalonia(Spain), 17 August 2003
(ECSS 2003, León, Spain, 9–12 November 2004)
American Museum of Natural History ''Science Bulletins: Derecho'' December 2003
Storm Severe weather and convection Weather hazards Wind * Spanish words and phrases