Supercell

Not to be confused withSuperstorm.

This article is about the weather phenomenon. For other uses, seeSupercell (disambiguation).

A drone photograph of a supercell from Chamberlain, South Dakota on July 18, 2023.

A supercell with a hail core nearStratford, Texason May 18, 2023.

Asupercellis athunderstormcharacterized by the presence of amesocyclone,a deep, persistently rotatingupdraft.Due to this, these storms are sometimes referred to as rotating thunderstorms.Of the four classifications of thunderstorms (supercell,squall line,multi-cell,andsingle-cell), supercells are the overall least common and have the potential to be the most severe. Supercells are often isolated from other thunderstorms, and can dominate the local weather up to 32 kilometres (20 mi) away. They tend to last 2–4 hours.

Supercells are often put into three classification types: classic (normal precipitation level), low-precipitation (LP), and high-precipitation (HP). LP supercells are usually found in climates that are more arid, such as the high plains of the United States, and HP supercells are most often found in moist climates. Supercells can occur anywhere in the world under the right pre-existing weather conditions, but they are most common in theGreat Plainsof the United States in an area known asTornado Alley.A high number of supercells are seen in many parts of Europe as well as in theTornado Corridor(es) ofArgentina,Uruguayand southernBrazil.

Characteristics

Supercells are usually found isolated from other thunderstorms, although they can sometimes be embedded in asquall line.Typically, supercells are found in the warm sector of a low pressure system propagating generally in a north easterly directionin line with the cold front of the low pressure system. Because they can last for hours, they are known as quasi-steady-state storms. Supercells have the capability to deviate from the mean wind. If they track to the right or left of the mean wind (relative to the verticalwind shear), they are said to be "right-movers" or "left-movers," respectively. Supercells can sometimes develop two separate updrafts with opposing rotations, which splits the storm into two supercells: one left-mover and one right-mover.

Supercells can be any size – large or small, low or high topped. They usually produce copious amounts ofhail,torrentialrainfall,strongwinds,and substantialdownbursts.Supercells are one of the few types of clouds that typically spawntornadoeswithin themesocyclone,although only 30% or fewer do so.

Geography

Supercells can occur anywhere in the world under the right weather conditions. The first storm to be identified as the supercell type was theWokinghamstorm overEngland,which was studied byKeith Browningand Frank Ludlam in 1962.Browning did the initial work that was followed up byLemonandDoswellto develop the modern conceptual model of the supercell.To the extent that records are available, supercells are most frequent in theGreat Plainsof the central United States and southern Canada extending into the southeastern U.S. and northernMexico;east-central Argentina and adjacent regions of Uruguay; Bangladesh and parts of eastern India; South Africa; and eastern Australia.Supercells occur occasionally in many othermid-latituderegions, including Eastern China and throughout Europe. The areas with highest frequencies of supercells are similar to those with the most occurrences of tornadoes; seetornado climatologyandTornado Alley.

Supercell anatomy

Schematic of a supercell's components

The current conceptual model of a supercell was described inSevere Thunderstorm Evolution and Mesocyclone Structure as Related to Tornadogenesisby Leslie R. Lemon and Charles A. Doswell III (seeLemon technique). Moisture streams in from the side of the precipitation-free base and merges into a line of warm uplift region where the tower of thethundercloudis tipped by high-altitude shear winds. The high shear causes horizontalvorticitywhich is tilted within the updraft to become vertical vorticity, and the mass of clouds spins as it gains altitude up to the cap, which can be up to 55,000 feet (17,000 m)–70,000 feet (21,000 m) above ground for the largest storms, and trailing anvil.

Supercells derive their rotation through the tilting of horizontalvorticity,which is caused bywind shearimparting rotation upon a rising air parcel by differential forces. Strong updrafts lift the air turning about a horizontal axis and cause this air to turn about a vertical axis. This forms a deep rotating updraft, themesocyclone.

Wind shear(red) sets air spinning (green).

Theupdraft(blue) 'bends' the spinning air upwards.

The updraft starts rotating with the spinning column of air.

Acaporcapping inversionis usually required to form an updraft of sufficient strength. The moisture-laden air is then cooled enough to precipitate as it is rotated toward the cooler region, represented by the turbulent air of themammatus cloudswhere the warm air is spilling over top of the cooler, invading air. The cap is formed where shear winds block further uplift for a time, until a relative weakness allows a breakthrough of the cap (anovershooting top); cooler air to the right in the image may or may not form ashelf cloud,but the precipitation zone will occur where theheat engineof the uplift intermingles with the invading, colder air. The cap puts an inverted (warm-above-cold) layer above a normal (cold-above-warm)boundary layer,and by preventing warm surface air from rising, allows one or both of the following:

• Air below the cap warms and/or becomes more moist
• Air above the cap cools

As the cooler but drier air circulates into the warm, moisture laden inflow, thecloud basewill frequently form a wall, and the cloud base often experiences a lowering, which, in extreme cases, are wheretornadoesare formed. This creates a warmer, moister layer below a cooler layer, which is increasingly unstable (because warm air is less dense and tends to rise). When the cap weakens or moves, explosive development follows.

In North America, supercells usually show up onDoppler weather radaras starting at a point or hook shape on the southwestern side, fanning out to the northeast. The heaviest precipitation is usually on the southwest side, ending abruptly short of therain-free updraft baseormain updraft(not visible to radar). Therear flank downdraft,or RFD, carries precipitation counterclockwise around the north and northwest side of the updraft base, producing a "hook echo"that indicates the presence of a mesocyclone.

Structure

Structure of a supercell. Northwestward view in theNorthern Hemisphere

Overshooting top

Main article:Overshooting top

This "dome" feature appears above the strongest updraft location on the anvil of the storm. It is a result of an updraft powerful enough to break through the upper levels of the troposphere into the lowerstratosphere.An observer at ground level and close to the storm may be unable to see the overshooting top because the anvil blocks the sight of this feature. The overshooting is visible from satellite images as a "bubbling" amidst the otherwise smooth upper surface of the anvil cloud.

Anvil

An anvil forms when the storm's updraft collides with the upper levels of the lowest layer of the atmosphere, or the tropopause, and has nowhere else to go due to the laws of fluid dynamics- specifically pressure, humidity, and density, in simple terms, the packet of air has lost its buoyancy and cannot rise higher. The anvil is very cold (-30°C) and virtually precipitation-free even thoughvirgacan be seen falling from the forward sheared anvil. Since there is so little moisture in the anvil, winds can move freely. The clouds take on their anvil shape when the rising air reaches 15,200–21,300 metres (50,000–70,000 ft) or more. The anvil's distinguishing feature is that it juts out in front of the storm like a shelf. In some cases, it can even shear backwards, called a backsheared anvil, another sign of a very strong updraft.

Precipitation-free base

This area, typically on the southern side of the storm in North America, is relatively precipitation-free. This is located beneath the main updraft, and is the main area of inflow. While no precipitation may be visible to an observer, large hail may be falling from this area. A region of this area is called the Vault. It is more accurately called the main updraft area.

Wall cloud

Thewall cloudforms near the downdraft/updraft interface. This "interface" is the area between theprecipitation areaand theprecipitation-free base.Wall clouds form when rain-cooled air from the downdraft is pulled into the updraft. This wet, cold air quickly saturates as it is lifted by the updraft, forming a cloud that seems to "descend" from the precipitation-free base. Wall clouds are common and are not exclusive to supercells; only a small percentage actually produce a tornado, but if a storm does produce a tornado, it usually exhibits wall clouds that persist for more than ten minutes. Wall clouds that seem to move violently up or down, and violent movements of cloud fragments (scud or fractus) near the wall cloud, are indications that a tornado could form.

Mammatus clouds

Mammatus(Mamma, Mammatocumulus) are bulbous or pillow-like cloud formations extending from beneath the anvil of a thunderstorm. These clouds form as cold air in the anvil region of a storm sinks into warmer air beneath it. Mammatus are most apparent when they are lit from one side or below and are therefore at their most impressive near sunset or shortly after sunrise when the sun is low in the sky. Mammatus are not exclusive to supercells and can be associated with developed thunderstorms and cumulonimbus.

Forward flank downdraft (FFD)

Diagram of supercell from above. RFD:rear flank downdraft,FFD:front flank downdraft,V:V-notch,U:Main Updraft,I:Updraft/Downdraft Interface,H:hook echo

This is generally the area of heaviest and most widespread precipitation. For most supercells, the precipitation core is bounded on its leading edge by ashelf cloudthat results from rain-cooled air within the precipitation core spreading outward and interacting with warmer, moist air from outside of the cell. Between the precipitation-free base and the FFD, a "vaulted" or "cathedral" feature can be observed. Inhigh precipitation supercellsan area of heavy precipitation may occur beneath the main updraft area where the vault would alternately be observed with classic supercells.

Rear flank downdraft (RFD)

Main article:Rear flank downdraft

The rear flank downdraft of a supercell is a very complex and not yet fully understood feature. RFDs mainly occur within classic and HP supercells although RFDs have been observed within LP supercells. The RFD of a supercell is believed to play a large part in tornadogenesis by tightening existing rotation within the surface mesocyclone. RFDs are caused by mid-level steering winds of a supercell colliding with the updraft tower and moving around it in all directions; specifically, the flow that is redirected downward is referred to as the RFD. This downward surge of relatively cool mid-level air, due to interactions between dew points, humidity, and condensation of the converging of air masses, can reach very high speeds and is known to cause widespread wind damage. The radar signature of an RFD is a hook-like structure where sinking air has brought with it precipitation.

Flanking line

Main article:flanking line (meteorology)

A flanking line is a line of smallercumulonimbior cumulus that form in the warm rising air pulled in by the main updraft. Due to convergence and lifting along this line,landspoutssometimes occur on the outflow boundary of this region.

Radar features of a supercell

Radar reflectivity map

Hook echo(or pendant)

The "hook echo" is the area of confluence between the main updraft and the rear flank downdraft (RFD). This indicates the position of the mesocyclone and probably a tornado.

Bounded weak echo region(or BWER)

This is a region of low radar reflectivity bounded above by an area of higher radar reflectivity with anuntilted updraft,also called avault.It is not observed with all supercells but it is at the edge of a very high precipitation echos with a very sharp gradient perpendicular to the RFD. This is evidence of a strong updraft and often the presence of atornado.To an observer on the ground, it could be experienced as a zone free of precipitation but usually containing large hail.

Inflow notch

A "notch" of weak reflectivity on the inflow side of the cell. This is not aV-Notch.

V Notch

A V-shaped notch on the leading edge of the cell, opening away from the main downdraft. This is an indication of divergent flow around a powerful updraft.

Hail spike

Thisthree body scatter spikeis a region of weak echoes found radially behind the main reflectivity core at higher elevations when large hail is present.

Descending reflectivity core

Main article:Descending reflectivity core

Supercell variations

Supercell thunderstorms are sometimes classified bymeteorologistsandstorm spottersinto three categories; however, not all supercells, being hybrid storms, fit neatly into any one category, and many supercells may fall into different categories during different periods of their lifetimes. The standard definition given above is referred to as theClassicsupercell. All types of supercells typically produce severe weather.

Low precipitation (LP)

Schematics of an LP supercell

A low precipitation supercell nearGreeley, Colorado

LP supercells contain a small and relatively light precipitation (rain/hail) core that is well separated from the updraft. The updraft is intense, and LPs are inflow dominant storms. The updraft tower is typically more strongly tilted and the deviant rightward motion less than for other supercell types. The forward flank downdraft (FFD) is noticeably weaker than for other supercell types, and the rear-flank downdraft (RFD) is much weaker—even visually absent in many cases. Like classic supercells, LP supercells tend to form within stronger mid-to-upper level storm-relative wind shear;however, the atmospheric environment leading to their formation is not well understood. The moisture profile of the atmosphere, particularly the depth of the elevated dry layer, also appears to be important,and the low-to-mid level shear may also be important.

This type of supercell may be easily identifiable with "sculpted" cloud striations in the updraft base or even a "corkscrewed" or "barber pole"appearance on the updraft, and sometimes an almost" anorexic "look compared to classic supercells. This is because they often form within drier moisture profiles (often initiated bydry lines) leaving LPs with little available moisture despite high mid-to-upper level environmental winds. They most often dissipate rather than turning into classic or HP supercells, although it is still not unusual for LPs to do the latter, especially when moving into a much moister air mass. LPs were first formally described byHoward Bluesteinin the early 1980salthough storm-chasing scientists noticed them throughout the 1970s.Classic supercells may wither yet maintain updraft rotation as they decay, becoming more like the LP type in a process known as "downscale transition" that also applies to LP storms, and this process is thought to be how many LPs dissipate.

LP supercells rarely spawn tornadoes, and those that form tend to be weak, small, and high-based tornadoes, but strong tornadoes have been observed. These storms, although generating lesser precipitation amounts and producing smaller precipitation cores, can generate huge hail. LPs may produce hail larger thanbaseballsin clear air where no rainfall is visible.LPs are thus hazardous to people and animals caught outside as well as to storm chasers and spotters. Due to the lack of a heavy precipitation core, LP supercells often exhibit relatively weak radar reflectivity without clear evidence of ahook echo,when in fact they are producing a tornado at the time. LP supercells may not even be recognized as supercells in reflectivity data unless one is trained or experienced on their radar characteristics.This is where observations bystorm spotterandstorm chasersmay be of vital importance in addition toDoppler velocity(andpolarimetric) radar data.

LP supercells are quite sought after by storm chasers because the limited amount of precipitation makes sighting tornadoes at a safe distance much less difficult than with a classic or HP supercell and more so because of the unobscured storm structure unveiled. During spring and early summer, areas in which LP supercells are readily spotted include southwesternOklahomaand northwesternTexas,among other parts of the westernGreat Plains.

High precipitation (HP)

Schematics of an HP supercell

High precipitation supercell inPhoenix,Arizona

TheHP supercellhas a much heavier precipitation core that can wrap all the way around the mesocyclone. These are especially dangerous storms, since the mesocyclone is wrapped with rain and can hide a tornado (if present) from view. These storms also cause flooding due to heavy rain, damagingdownbursts,and weak tornadoes, although they are also known to produce strong to violent tornadoes. They have a lower potential for damaging hail than Classic and LP supercells, although damaging hail is possible. It has been observed by some spotters that they tend to produce more cloud-to-ground and intracloud lightning than the other types. Also, unlike the LP and Classic types, severe events usually occur at the front (southeast) of the storm. The HP supercell is the most common type of supercell in theUnited Stateseast ofInterstate 35,in the southern parts of the provinces ofOntarioandQuebecinCanada,inFrance,Germanyand thePo Valleyin north Italy and in the central portions of Argentina andUruguay.

Mini-supercell or low-topped supercell

Whereasclassic,HP, and LP refer to different precipitation regimes and mesoscale frontal structures, another variation was identified in the early 1990s by Jon Davies.These smaller storms were initially called mini-supercellsbut are now commonly referred to as low-topped supercells. These are also subdivided into Classic, HP and LP types.

Effects

Satellite view of a supercell

Supercells can produce hailstones averaging as large as two inches (5.1 cm) in diameter, winds over 70 miles per hour (110 km/h),tornadoesof as strong as EF3 to EF5 intensity (if wind shear and atmospheric instability are able to support the development of stronger tornadoes), flooding, frequent-to-continuouslightning,and very heavy rain. Manytornado outbreakscome from clusters of supercells. Large supercells may spawn multiple long-tracked and deadly tornadoes, with notable examples in the2011 Super Outbreak.

Severe events associated with a supercell almost always occur in the area of the updraft/downdraft interface. In theNorthern Hemisphere,this is most often the rear flank (southwest side) of the precipitation area inLPandclassicsupercells, but sometimes the leading edge (southeast side) ofHPsupercells.

Examples worldwide

Asia

Some reports suggest that thedelugeon 26 July 2005 inMumbai,Indiawas caused by a supercell when there was a cloud formation 15 kilometres (9.3 mi) high over the city. On this day 944 mm (37.2 in) of rain fell over the city, of which 700 mm (28 in) fell in just four hours. The rainfall coincided with a high tide, which exacerbated conditions.

Supercells occur commonly from March to May in Bangladesh, West Bengal, and the bordering northeastern Indian states including Tripura. Supercells that produce very high winds with hail and occasional tornadoes are observed in these regions. They also occur along the Northern Plains of India and Pakistan. On March 23, 2013, a massive tornado ripped through Brahmanbaria district in Bangladesh, killing 20 and injuring 200.

Australia

Photo of the 1947 Sydney Hailstorm showing the hail hitting the water at Rose bay

On New Year's Day 1947 a supercell hitSydney.The classic type Supercell formed over the Blue Mountains, mid-morning hitting the lower CBD and eastern suburbs by mid-afternoon with the hail similar in size to a cricket ball. At the time, it was the mostsevere storm to strike the citysince recorded observations began in 1792.

On April 14, 1999,a severe stormlater classified as a supercell hit the east coast of New South Wales. It is estimated that the storm dropped 500,000 tonnes (490,000 long tons; 550,000 short tons) worth of hailstones during its course. At the time it was the most costly disaster in Australia's insurance history, causing an approximated A$2.3 billion worth of damage, of which A$1.7 billion was covered by insurance.

On February 27, 2007, a supercell hitCanberra,dumping nearly thirty-nine centimetres (15 inches) of ice inCivic.The ice was so heavy that a newly built shopping center's roof collapsed, birds were killed in the hail produced from the supercell, and people were stranded. The following day many homes in Canberra were subjected to flash flooding, caused either by the city's infrastructure's inability to cope with storm water or through mud slides from cleared land.

On 6 March 2010,supercell stormshitMelbourne.The storms caused flash flooding in the center of the city and tennis ball-sized (10 cm or 4 in) hailstones hit cars and buildings, causing more than $220 million worth of damage and sparking 40,000-plus insurance claims. In just 18 minutes, 19 mm (0.75 in) of rain fell, causing havoc as streets were flooded and trains, planes, and cars were brought to a standstill.

That same month, onMarch 22, 2010a supercell hitPerth.This storm was one of the worst in the city's history, causing hail stones of 6 centimetres (2.4 in) in size and torrential rain. The city had its average March rainfall in just seven minutes during the storm. Hail stones caused severe property damage, from dented cars to smashed windows.The storm itself caused more than 100 million dollars in damage.

OnNovember 27, 2014a supercell hit the inner city suburbs including the CBD ofBrisbane.Hailstones up to softball size cut power to 71,000 properties, injuring 39 people,and causing a damage bill of $1 billion AUD.A wind gust of 141 km/h was recorded atArcherfield Airport

South America

An area in South America known as theTornado Corridoris considered to be the second most frequent location for severe weather, after Tornado Alley in the United States.The region, which covers portions ofArgentina,Uruguay,Paraguay,andBrazilduring the spring and summer, often experiences strong thunderstorms which may include tornadoes. One of the first known South American supercell thunderstorms to include tornadoes occurred on September 16, 1816, and destroyed the town of Rojas (240 kilometres (150 mi) west of the city of Buenos Aires).

On September 20, 1926, an F4 tornado struck the city of Encarnación (Paraguay), killing over 300 people and making it the second deadliest tornado in South America. On 21 April 1970, the town of Fray Marcos in the Department of Florida, Uruguay experienced an F4 tornado that killed 11, the strongest in the history of the nation. January 10, 1973, saw the most severe tornado in the history of South America: TheSan Justo tornado,105 km north of the city ofSanta Fe(Argentina), was rated F5, making it the strongest tornado ever recorded in the southern hemisphere, with winds exceeding 400 km/h. On April 13, 1993, in less than 24 hours in the province ofBuenos Aireswas given the largest tornado outbreak in the history of South America. There were more than 300 tornadoes recorded, with intensities between F1 and F3. The most affected towns were Henderson (EF3), Urdampilleta (EF3) and Mar del Plata (EF2). In December 2000, a series of twelve tornadoes (only registered) affected the Greater Buenos Aires and the province of Buenos Aires, causing serious damage. One of them struck the town of Guernica, and, just two weeks later, in January 2001, an F3 again devastated Guernica, killing 2 people.

The December 26, 2003, Tornado F3 happened inCordoba,with winds exceeding 300 km/h, which hit Córdoba Capital, just 6 km from the city center, in the area known as CPC Route 20, especially neighborhoods of San Roque and Villa Fabric, killing 5 people and injuring hundreds. The tornado that hit the State ofSão Pauloin 2004 was one of the most destructive in the state, destroying several industrial buildings, 400 houses, killing one and wounding 11. The tornado was rated EF3, but many claim it was a tornado EF4.In November 2009, four tornadoes, rated F1 and F2 reached the town of Posadas (capital of the province ofMisiones,Argentina), generating serious damage in the city. Three of the tornadoes affected the airport area, causing damage in Barrio Belén. On April 4, 2012, the Gran Buenos Aires was hit by the storm Buenos Aires, with intensities F1 and F2, which left nearly 30 dead in various locations.

On February 21, 2014, in Berazategui (province of Buenos Aires), a tornado of intensity F1 caused material damage including a car was, with two occupants inside, which was elevated a few feet off the ground and flipped over asphalt, both the driver and his passenger were slightly injured. The tornado caused no fatalities. The severe weather that occurred on Tuesday 8/11 had features rarely seen in such magnitude in Argentina. In many towns ofLa Pampa,San Luis,Buenos Aires and Cordoba, intense hail stones fell up to 6 cm in diameter. On Sunday December 8, 2013, severe storms took place in the center and the coast. The most affected province was Córdoba, storms and supercells type "bow echos" also developed in Santa Fe and San Luis.

Europe

See also:Spanish plume

Europe has its own hotspots for tornadoes and severe weather. Especially in the summer months damaging supercells occur frequently and parts of France, Germany and north Italy are experiencing a number of strong and violent tornadoes every decade.

During the evening ofAugust 3, 2008,a supercell formed over northern France. It spawned an F4 tornado in the Val de Sambre area, about 90 kilometers east ofLille,which impacted nearby cities such asMaubeugeandHautmont.This same supercell later went on to generate other tornadoes in the Netherlands and Germany.

In 2009, on the night of Monday May 25, a supercell formed overBelgium.It was described by Belgian meteorologist Frank Deboosere as "one of the worst storms in recent years" and caused much damage in Belgium – mainly in the provinces of East Flanders (around Ghent), Flemish Brabant (around Brussels) and Antwerp. The storm occurred between about 1:00 am and 4:00 am local time. An incredible 30,000 lightning flashes were recorded in 2 hours – including 10,000 cloud-to-ground strikes. Hailstones up to 6 centimetres (2.4 in) across were observed in some places and wind gusts over 90 km/h (56 mph); in Melle near Ghent a gust of 101 km/h (63 mph) was reported. Trees were uprooted and blown onto several motorways. In Lillo (east of Antwerp) a loaded goods train was blown from the rail tracks.

On May 24, 2010, an intense supercell left behind a trail of destruction spanning across three different states in eastern Germany. It produced multiple strong downbursts, damaging hail and at least four tornadoes, most notably an F3 wedge tornado which struck the town ofGroßenhain,killing one person.

On August 18, 2011, the rock festivalPukkelpopin Kiewit, Hasselt (Belgium) may have been impacted by a supercell withmesocyclonearound 18:15. Tornado-like winds were reported, trees of over 30 centimetres (12 in) diameter were felled and tents came down. Severe hail scourged the campus. Six people reportedly died and over 140 people were injured. The event was suspended. Buses and trains were mobilised to bring people home.

On June 28, 2012,three supercellsaffected England. Two of them formed over the Midlands, producing hailstones reported to be larger than golf balls, with conglomerate stones up to 10 cm across. Burbage in Leicestershire saw some of the most severe hail. Another supercell produced a tornado near Sleaford, in Lincolnshire.

A third supercell affected theNorth Eastregion of England. The storm struck theTynesidearea directly and without warning during evening rush hour causing widespread damage and travel chaos, with people abandoning cars and being trapped due to lack of public transport. Flooded shopping malls were evacuated,Newcastle stationwas shut, as was theTyne & Wear Metro,and main road routes were flooded leading to massive tailbacks. 999 land line services were knocked out in some areas and the damage ran to huge amounts only visible the next day after water cleared. Many parts ofCounty DurhamandNorthumberlandwere also affected, with thousands of homes across the North East left without power due to lightning strikes.

On July 28, 2013, an exceptionally long-lived supercell tracked along an almost 400 km long path across parts ofBaden-WürttembergandBavariain southernGermany,before falling apart inCzechia.The storm had a lifespan of around 7 hours and produced large hail of up to 8 cm in diameter. The city ofReutlingenwas hit the hardest, houses and cars were severely damaged, dozens of people injured.With roughly 3.6 billion euros worth of damage, it was by far the costliest thunderstorm event ever documented in Germany.

Throughout June 2014,an outbreak of severe supercells occurred in western Europe,producing a lot of damaging hail especially in France. In theParis area,some hailstones reached 8 cm of diameter but the biggest was found in theLoiretdepartment with an exceptional diameter of 12 cm.

On 25 July 2019 a supercell thunderstorm affected northern England and parts of Northumberland. Large hail, frequent lightning and rotation were reported by many people. On 24 September 2020 a similar event affected parts of West Yorkshire.

This damage was caused by the supercell storm which hitCroatiaand neighbouring countries on 19 July 2023.

On the morning of June 19, 2021, a MCS developed over the French Atlantic coast. While progressing to the north, the system gained supercellular aspects and spawned a F2 tornado 60 kilometers west ofTours.It reachedParis and its surroundingsin the late afternoon, causing flash floods in the area due to heavy rainfalls. The system continued its path towards the Belgian frontier, reaching peak intensity: in the way, one of the peripheral supercells evolved into HP status just before entering the city ofReims.The main mesocyclone suddenly expanded and turned into a massive shelf cloud, a typical structure of the Tornado Alley. It produced strong gust winds, rainfalls and hail and inflicted a lot of damage over the nearby areas.

Only 5 days after that on June 24, 2021, a supercell produced an F4 tornado insouth Moravia,Czech Republic. This tornado caused 6 deaths and left more than 200 people injured. With roughly $700 million of damage it was one of the costliest tornadoes to occur outside of the United States.

InEurope,the mini-supercell, or low-topped supercell, is very common, especially when showers and thunderstorms develop in cooler polar air masses with a strong jet stream above, especially in the left exit-region of ajetstreak.

North America

TheTornado Alleyis a region of the central United States where severe weather is common, particularly tornadoes. Supercell thunderstorms can affect this region at any time of the year, but they are most common in the spring.Tornado watchesandwarningsare frequently necessary in the spring and summer. Most places from theGreat Plainsto theEast Coast of the United Statesand north as far as theCanadian Prairies,theGreat Lakes region,and theSt. Lawrence Riverwill experience one or more supercells each year.

Gainesville, Georgiawas the site of thefifth deadliest tornado in U.S. historyin 1936, where Gainesville was devastated and 203 people were killed.

The1980 Grand Island tornado outbreakaffected the city ofGrand Island, Nebraskaon June 3, 1980. Seven tornadoes touched down in or near the city that night, killing 5 and injuring 200.

TheElie, Manitoba tornadowas anF5that struck the town ofElie, Manitobaon June 22, 2007. While several houses were leveled, no one was injured or killed by the tornado.

A massivetornado outbreakon May 3, 1999 spawned anF5 tornadoin the area ofOklahoma Citythat had the highest recorded winds on Earth.This outbreakspawned over 66 tornadoesinOklahomaalone. On this day throughout the area of Oklahoma,Kansas,andTexas,over 141 tornadoes were produced. This outbreak resulted in 50 fatalities and 895 injuries.

A series of tornadoes, which occurred in May 2013, caused severe devastation to Oklahoma City in general. The first tornado outbreaks occurred onMay 18 to May 21when a series of tornadoes hit. From one of the storms developeda tornadowhich was later ratedEF5,which traveled across parts of the Oklahoma City area, causing a severe amount of damage. This tornado was first spotted inNewcastle.It touched the ground for 39 minutes, crossing through a heavily populated section ofMoore.Winds with this tornado peaked at 210 miles per hour (340 km/h).Twenty-three fatalities and 377 injuries were caused by the tornado.Sixty-one other tornadoeswere confirmed during the storm period. Later on in the same month, on the night of May 31, 2013, another eight deaths were confirmed from what became thewidest tornado on recordwhich hit El Reno, Oklahoma, one ofa series of tornadoesandfunnel cloudswhich hit nearby areas.

South Africa

South Africa witnesses several supercell thunderstorms each year with the inclusion of isolated tornadoes. On most occasions these tornadoes occur in open farmlands and rarely cause damage to property, as such many of the tornadoes which do occur in South Africa are not reported. The majority of supercells develop in the central, northern, and north eastern parts of the country. The Free State, Gauteng, and Kwazulu Natal are typically the provinces where these storms are most commonly experienced, though supercell activity is not limited to these provinces. On occasion, hail reaches sizes in excess ofgolf balls,and tornadoes, though rare, also occur.

On 6 May 2009, a well-defined hook echo was noticed on local South African radars, along with satellite imagery this supported the presence of a strong supercell storm. Reports from the area indicated heavy rains, winds and large hail.

On October 2, 2011, two devastating tornadoes tore through two separate parts of South Africa on the same day, hours apart from each other. The first, classified as an EF2 hit Meqheleng, the informal settlement outside Ficksburg, Free State which devastated shacks and homes, uprooted trees, and killed one small child. The second, which hit the informal settlement of Duduza, Nigel in the Gauteng province, also classified as EF2 hit hours apart from the one that struck Ficksburg. This tornado completely devastated parts of the informal settlement and killed two children, destroying shacks and RDP homes.

Gallery

Supercell In Kansas

Supercell In Kansas

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  Arcus in Poland
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  Supercell in Oklahoma
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  Supercell in Norman, Oklahoma
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  Rotating thunderstorm updraft
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  Chaparral, New Mexico, supercell
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  2013 Moore tornadoin Oklahoma
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  Supercell in Needmore, Texas

See also

• Convective storm detection
• Pseudo-cold front
• Pseudo-warm front

External links

• Structure and Dynamics of Supercell Thunderstorms
• Lemon, Leslie R., (1998)On the Mesocyclone "Dry Intrusion" and Tornadogenesis
• Electronic Journal of Severe Storms Meteorology