Photos of debris give researchers insight into tornados

Photos and mementos that were snatched up and blown hundreds of miles during tornados in the south of the United States two years ago are giving researchers new insight on how debris is carried by the storms and how it could threaten the public.

A new study has documented how one photo travelled nearly 355 kilometres over Alabama and Tennessee, said John Knox, an associate professor of geography at the University of Georgia who led the research. That is among the longest-documented trajectories of tornado debris.

The slightly scratched snapshot, which shows a stream flowing through a mountainous landscape, travelled from the northwest Alabama town of Phil Campbell to the east Tennessee town of Lenoir City.
The study was recently published online by the Bulletin of the American Meteorological Society.

It tracked the direction the items travelled in relation to the storms that struck Alabama and other Southern states on April 27, 2011.

The researchers analysed the takeoff and landing points of the items using geography software and mathematical models.

Most debris fell slightly to the left of the storm's track. But the items that travelled the farthest were found to the right of the path.

Knowing where the debris is likely to fall could help protect the public if a tornado were to strike a hazardous site and suck up toxic biological or radioactive debris, Knox said.

"We need to get enough understanding so we can get fairly reasonable predictions of where the stuff goes," said John Snow, a professor of meteorology and dean emeritus at the University of Oklahoma who studied tornado debris in the 1990s. Knox's study builds on research done by Snow and others.

Though nuclear reactors are designed to withstand the force of tornadoes, radioactive materials such as fuel rods are often stored nearby, Snow said. A direct hit on such material is one of many catastrophic scenarios involving tornado-blown debris.

Tornadoes have struck toxic materials in the past. In May 2008, a twister slammed into some of the mountains of mining waste that dot the landscape of Oklahoma's Tar Creek Superfund site.

Joshua Wurman, an atmospheric scientist who founded the Center for Severe Weather Research in Boulder, Colorado, was not involved in the Georgia research but thinks it could have benefits.

"Let's say a tornado struck some kind of toxic waste dump. Sure, some of the debris or dust would have some contaminants in that," Wurman said. "Understanding which direction those contaminants would go could be useful."

The 934 objects studied by Knox and his students were posted on a Facebook page and later claimed by their owners.

Patty Bullion created the site hours after the tornadoes struck, when several photos and scraps of paper were found in her neighbourhood in the northern Alabama town of Lester. She began posting the pictures on her site. Around 2,000 of those photos and documents eventually were claimed by their owners and returned to them. That gave the researchers a gold mine of raw data on which to build.

"I was very thankful that the page could be a help," Bullion said. "I never dreamed that it would send as many pictures home as it did and then help with research like that. God works in mysterious ways."

Bullion has since taken down the Facebook site. The items pictured there are highly personal, she said, and she didn't want them to be on Facebook forever.

The historic 2011 tornado outbreak in the South, combined with Bullion's social media effort, represented a unique opportunity for the new study, Knox said.

On April 27, 2011, more than 120 tornadoes caused more than 300 deaths across the South.
The items studied from the 2011 outbreak represent "just a small cross section of debris that just carpeted the Southeast," said Knox. "What was amazing was that there was so much debris that went so far."

An earlier study on tornado debris by Snow and his colleagues identified only two objects that had travelled about 215 kilometres. By contrast, the Georgia study identified 44 items that travelled a comparable distance or farther.

The nearly 220 miles covered by the landscape photo sucked up by one of the Alabama tornadoes rivals the path taken by a cancelled check from Stockton, Kansas, which was struck by a tornado in 1991. The check was carried 359 kilometres from Kansas to a farm near Winnetoon, Nebraska, according to records from the World Meteorological Organization.

Knox said the response from his students, who became co-authors of the research paper, was phenomenal.
Knox said he sought to teach them how to conduct the research in a way that was ethical and sensitive to the victims since the tornadoes destroyed lives and homes.

"Hopefully that's a message that the students will take with them," he said. "In this case, we had people whose houses were destroyed and the family members killed and the only thing they may have gotten back was a picture of Grandma and Grandpa that went 150 miles into another state."

- Times Live

Photos: Tornado observed over Kriel, Mpumalanga, Saturday 02 March

 (Click on images for larger view.)

Paul Andrews writes: Please see attached photos of what came to town on Saturday morning just before my daughter's hockey game, at Kriel, Mpumalanga.

It was outside of town and far off, probably about 10km and it never touched down.

What's really strange about it is that it was not a day of severe weather systems.

The morning began cool and overcast with patches of light rain and drizzle, almost like a cold front.

There was no major build-up of severe heat and then the sudden icy cold of hail-laden storm clouds, together with violent gusting winds.

Instead it was calm, only slightly breezy and moderate. This was not in any way a day filled with perfect tornado-forming weather.

The funnel lasted about 10 minutes and then was gone again.

SAWDOS:  Paul thanks so much for the funnel images.  This is a great observation taken into account that the conditions were not conducive for the formation of tornadoes.   However one never knows when mother nature will come up with a surprise. 

Large tornado hits Hattiesburg, Mississippi

A strong cold front triggering blizzard conditions across northern Nebraska, South Dakota, North Dakota, and Minnesota is also triggering severe weather across the deep south today (Sunday, February 10, 2013). The Storm Prediction Center issued a slight risk for severe weather across Louisiana, southern Mississippi, and southern Alabama for a threat to see a few strong tornadoes, large hail, and strong winds. During the evening hours, supercells developed across southern Mississippi and produced very distinct signatures on radar that would indicate strong rotation and possible tornadoes. One confirmed tornado struck the city of Hattiesburg, Mississippi around 5 p.m CST (22:00 UTC). There have been numerous reports of severe damage to buildings, structures, and what appears to be a direct hit through the University of Southern Mississippi. In this post, we have included some images and videos that were posted via social media. It is still too early to know if any injuries or deaths occurred with this particular storm. Once we get more details, we will let you know.

User name “Ryan iz Legend” posted this image of the tornado that hit Hattiesburg, Mississippi via instagram.

Information is still coming out at the moment, but it looks like the city of Hattiesburg was struck the hardest. According to reports via twitter, Southern Mississippi reports tornado damage at Jazz Station, Mannoni Performing Arts Center, Ogletree Alumni House and Elam Arms.

Here is some amazing footage by John Sibley in Hattiesburg, Mississippi:

The USM Alumni house was one of the many buildings hit by the strong tornado in Hattiesburg, Mississippi. Image Credit: WDAM-TV

Damage in Hattiesburg, Mississippi. Image Credit: Brent Jones (@Brentjones4)

Here is a radar image shortly after the tornado hit Hattiesburg, Mississippi. It shows both reflectivity (top) and velocity (bottom) images that help indicate rotation and a possible tornado in the storm.

Bottom line: A large tornado struck Hattiesburg, Mississippi around 5 p.m. CST on Sunday, February 10, 2013. Based on the storm reports, it appears as if injuries have occurred with this particular tornado, although nothing has been confirmed as of now. Based on radar images, video, pictures, and damage reports, this tornado will likely be ranked as an EF-2 or EF-3 tornado. We will know more about the extent of the damage tomorrow when we have daylight and the National Weather Service can begin a survey. Prayers go out to all of the victims involved in not only this particular storm, but all across the region experiencing severe weather this evening.

- EarthSky

Underwater fish tornado off Baja California

We saw a fire tornado, and in recent months it’s been a photo of a “fish tornado” making the rounds. Photographer and marine biologist Octavio Aburto captured this amazing photo of the at Cabo Pulmo National Park in Mexico, in the course of studying the courtship behavior of a species of Jack fish. He titled it “David and Goliath.”

Image: Photographer and marine biologist Octavio Aburto captured this amazing photo at Cabo Pulmo National Park in Mexico. He calls it “David and Goliath.”

Aburto said he hopes the image will foster appreciation for the marine universe, for Cabo Pulmo National Park in particular, and will “bring attention to other successful marine reserves, especially in Latin America.”

Mission Blue has an interview with Aburto, explaining how his scientific background inspired him to snap the mysterious imagery. Among other things, Aburto said:

The picture you see was taken November 1, 2012. But this picture has been in my mind for three years — I have been trying to capture this image ever since I saw the behavior of these fish and witnessed the incredible tornado that they form during courtship. So, I guess you could say this image took almost three years.



Bottom line: Fish tornado photo – titled “David and Goliath” – taken off Cabo Pulmo National Park in Baja, California on November 1, 2012.

- EarthSky

Photos: Tornado/Funnel Clouds Observed recently in South Africa

Images supplied by Ziyaad Warasally - Mooiriver tornado as seen from Weston. Occurred around 17h00 19 December 2012 and lasted for 2 minutes. Never touched down.

Posted: 18h23 19/12/212 - reptrail IAN-FLYING DUTCMAN 12m The storm hitting Mooiriver

Image from @Rbrayley on twitter. 19 December 2012 - Seen here is a funnel cloud and wall cloud making me believe that this was indeed a supercellular tornado

Des Jacobs - This one was just south of Lydenburg on Sunday 25 November 2012. I watched it for approx 20 minutes or so but it never touched the ground.

Marida Jooste - Kestell: Foto van gister 17 Desember2012, het ook die punt gesien. Daar was redelik wind, maar dit het nie tot op grond gegaan nie. Tornado's kom nog al redelik in die area voor.

"Tornado" next to N4 approx. 50Km from Machadadorp (18 December 2012)- We were driving back from Jhb to Nelspruit this afternoon and it was great to this tornado less than 1Km next to N4 (approx. 50Km from Machadadorp)! It only lasted about 5 minutes after we first spotted it. - Way to Grow

The skyline last night (9 December 2012) at Sutherland Observatory. Pictures were taken between 18h53 and 18h58 in a westerly direction from SALT.

Aileen Hutchinson managed to take a photo of the twister funnel forming on the 25 November 2012 on the N1 Highway between Pretoria and Polokwane.

"Tornado" next to N4 approx. 50Km from Machadadorp (18 December 2012)

We were driving back from Jhb to Nelspruit this afternoon and it was great to this tornado less than 1Km next to N4 (approx. 50Km from  Machadadorp)!   It only lasted about 5 minutes after we first spotted it. - Way to Grow

Video: Tornado in the Karoo - Sutherland (9 December 2012)

Published on Dec 10, 2012

Martin Wilkinson, Systems Engineer at the SALT Telescope witnessed this very rare phenomena on Sunday, 9 December 2012 when a "twister" formed in the Karoo during stormy weather conditions and actually touched down and picked up debris. - Willie Koorts

Tornado observed in the Sutherland District (9 December 2012 18h53 SAST)

The skyline last night at Sutherland Observatory. Pictures were taken between 18h53 and 18h58 in a westerly direction from SALT.

Images: Martin Wilkinson. (Click on images for larger view.)

Tornado vs motorist on the N1 highway

Aileen Hutchinson managed to take a photo of the twister funnel forming with her phone.

Aileen Hutchinson, a Tzaneen resident, had a close encounter of a different kind while driving between Pretoria and Polokwane.

http://www.looklocal.co.za/looklocal/content/en/tzaneen-and-surrounds/tzaneen-and-surrounds-news-general?oid=6582046&sn=Detail&pid=4981439&Tornado-vs-motorist-on-the-N1-highway

- Letaba Herald (LookLocal)

Weather History: Riebeeckstad / Welkom Tornado 20 March 1990

Who still remember the Welkom Tornado that occurred on 20 March 1990? Here is a video that was posted on Youtube.

Large, violent tornado caught on video in Italy on November 28

A large and violent tornado struck southern Italy earlier today (November 28, 2012.)

As of now, at least 20 people that were injured from this tornado. There are already unconfirmed reports of at least three deaths from this destructive tornado.

Tornadoes are generally a rare phenomenon, but they do occur in Europe and are not completely unusual. Tornadoes and severe weather are typically common in the fall and spring months of the year as weather transitions from warm air masses to cooler air masses and vice versa.

Check out this amazing video. Pray that everyone that was impacted by this tornado and the other severe storms in this region are safe and sound.

Check out this amazing video of the same tornado that created a fire in the city.

Bottom line: A large, violent tornado struck Taranto, Italy earlier today (November 28, 2012) that has resulted in at least 20 injuries.

- EarthSky

Tornado - Europe - Spain

A tornado swept through a fair ground in a Spanish town, knocking down a Ferris wheel and injuring 35 people, while the death toll from flooding in the southern part of the country rose to eight, authorities said Saturday. The Friday tornado damaged several rides and cut electricity in the temporary fair set up in the main square of Gandia, according to its town hall website. It said 15 of the injured were seriously hurt, all of whom were treated on site. Local media reported the fair was closed to the public at the time of a thunderstorm and that all the injured were fair workers. Just inland from the Mediterranean coastal town, three more victims of Friday's flash floods were found overnight. They included a middle-aged woman in the town of Lorca.

-RSOE EDIS

Video: Fire tornado!

THERE'S something mean and magical about Australia's Outback. An Alice Springs filmmaker captured both when a whirlwind of fire erupted before his eyes.

Chris Tangey of Alice Springs Film and Television was scouting locations near Curtin Springs station, about 80km from Ularu, last week when confronted by a fiery phenomenon.

He had just finished his tour of the station when workers encountered difficulties with a grader. So he went to help them.

A small fire was burning in nearby bushland, so Mr Tangey decided to start filming. He caught the sight of his life. A twister touched down on the spot fire, fanning it into a furious tower of flame.

"It sounded like a jet fighter going by, yet there wasn't a breath of wind where we were," he told the
Northern Territory News.

"You would have paid $1000 a head if you knew it was about to happen."

The column of fire danced about the landscape for about 40 minutes, he said, as he and the station workers stood transfixed.

There was talk of making a quick getaway, Mr Tangey said. But everyone was too hypnotised to feel scared - and he continued furiously filming.

"The bizarre thing was that it rarely moved," he said.

"These things just stood there because there was no wind to move them ... but it was flickering incredibly fast."

Darwin weather forecaster David Matthews said small twisters were common in isolated areas. But the fiery vortex was highly unusual.

"The flames would have assisted by trying to suck in air and that could have helped generate those circular winds," Mr Matthews said.

- 7 News

Tornadoes in Poland Kill 1, Injure 10

A freak wave of summer tornadoes has struck northern and western Poland, killing at least one person and injuring another 10 people.

An area around Bory Tucholskie forest, a national park and popular tourist destination, was hit by a twister between 800 and 1,000 meters (875-1,100 yards) wide. More than 400 hectares (nearly 1,000 acres) of woodland were flattened in the area, authorities said, and more than 100 houses destroyed.

Power lines were downed and roads were closed as hundreds of firefighters worked to clear away fallen trees. Some trains had to make detours after debris fell onto tracks.

Firefighter Mieczyslaw Torlop told the TVN station that one man was killed in the village of Wycinki after being crushed by his house, which collapsed.

- ABC NEWS

Aid on the way for Free State community

Bloemfontein - More aid was on the way for Kestel, Free State residents affected by a severe storm at the weekend, charity group Gift of the Givers said on Tuesday.

"Our building teams are already at work preparing temporary shelters in the form of Zozos [huts]," director Imtiaz Sooliman said.

A violent storm - which some described as a tornado - passed through Kestel, Bethlehem and other areas of the Thabo Mofutsanyana municipality, causing extensive damage on Saturday.

A total of 81 houses and a church were damaged, the provincial co-operative governance and traditional affairs department said earlier.

Roofs were blown off, walls collapsed and power lines were damaged, spokesperson Senne Bogatsu said. The electricity supply was gradually being restored on Monday.

Bogatsu said local shops had donated food and clothing to those in need.

Sooliman said local residents had also been generous to neighbours who had lost possessions in the storm.

"The South African spirit of ubuntu never fails, and the compassion of our people never ceases to amaze."

Sooliman said Gift of the Givers teams were on their way with tents, blankets, mattresses, clothing, food parcels, supplies for bulk feeding and hygiene packs.

- SAPA/News24

Haar man sterf kort voor tornado seun eis

Die vakansiehuis waarin Jean Coetzee Saterdagaand dood is toe ’n tornado die gebied getref het. Foto: Wolfram Zwecker

“Hy het altyd gesê ek is nie sy ma nie, ek is sy ousus.”

So het Colleen Coetzee (41) gister gesê nadat haar seun, Jean (22), die naweek dood is in een van die talle tornado’s wat die Oos- en die Noordoos-Vrystaat getref het.

Jean is deur konst. Peter Karedi, polisiewoordvoerder, verkeerdelik aan Beeld geïdentifiseer as Eugene Coetzee, ’n student aan die Noordwes-Universiteit se Potchefstroom- kampus, wat in Germiston woon.

Coetzee, van Alberton, het gister gesê sy het twee weke gelede haar man, Jacques (43), ook aan die dood afgestaan.

“Jean was met sowat 14 vriende op ’n naweekuitstappie by die Vaaldam by Oranjeville. Hy het saam met sy groep vriende gaan ontspan,” het Coetzee gesê.

Volgens haar het van sy vriende vertel hulle het die tornado sien aankom terwyl hulle gebraai het en in die chalet ingehardloop.

Jean en een van sy vriende was glo van die laastes om in te hardloop. Jean is dood toe die tornado die grasdak-chalet tref.

Volgens Coetzee het hy kopbeserings opgedoen.

“Die kinders het vir my gesê dat alles so vinnig gebeur het. Ek weet nie hoe om vir jou te sê hoe ek voel nie,” het Coetzee gesê.

Twee weke gelede het sy haar man begrawe. “Dit voel nie asof Jean weg is nie.”

Sy het gesê dat sy nog nie aanvaar dat hy dood is nie.

“Ek was baie lief vir hom.”

Coetzee het gesê sy en Jean het baie met mekaar gespot.

“Hy het altyd my siel uitgetrek. Hy het my sy ousus genoem. Ek gaan veral sy glimlag mis.”

Jean was ’n “party animal” en het gehou van uitgaan, het Coetzee gesê.

Coetzee en haar jongste seun, Sean (17), is al wat oor is van die gesin van vier.

“Gelukkig het ek ’n groot familie wat my ondersteun,” het sy gesê.

Jean se gedenkdiens is Maandag 14:00 in die Alberton Metodiste-kerk.

- Beeld

Video: Tornadoes struck the Free State

- SABC Digital News

Hulp stroom in ná tornado tref

BLOEMFONTEIN. – Hulp stroom in vir slagoffers wat dakloos en sonder heenkome gelaat is toe ’n sterk tornado en rukwinde die naweek groot skade in dele van die Oos-Vrystaat veroorsaak het.

Op Kestell, waar meer as 81 huise en ’n kerk in die Tlholong-woongebied in die slag gebly het toe ’n tornado hier verwoesting gesaai het, het boere, kerkleiers en ander weldoeners vinnig ingespring om slagoffers te hulp te snel.

Rampbestuur het veral ’n nood vir kos en komberse geïdentifiseer.

Vroue van die NG gemeente op die dorp het ingestem om tot môre sop en brood aan sowat 150 inwoners te verskaf, terwyl twee boere in die distrik tans sowat 300 inwoners van warm kos voorsien.

Die Rooi Kruis het 60 komberse aan behoeftiges geskenk.

Sowat 20 komberse is ook aan plaaswerkers van die Welgegund-plaas op Eeram by Harrismith oorhandig en kos is ook hierheen gestuur.

Senne Bogatsu, woordvoerder van die Vrystaatse departement van samewerkende regering, het gesê die regeringsagentskap vir maatskaplike sekerheid maak kospakkies bymekaar en sal dit na verwagting môre aan inwoners oorhandig.

Die meeste slagoffers word deur gemeenskapslede gehuisves, terwyl die gemeenskapsentrum op Kestell ook reg staan om slagoffers te huisves.

Op Christenburg, Bethlehem, het lede van die gemeenskap kos aan inwoners oorhandig, het Clem Harrington, lid van die burgemeesterskomitee, gesê.

Dit kom nadat twee huise verwoes en ander se dakke deur rukwinde afgeruk is.

Anita Schoeman van Solidariteit se Helpende Hand het gesê mense wat dakloos gelaat is, word in die kerksaal gehuisves. Komberse en warm kos sal welkom wees.

Intussen het die Dihlabeng-munisipaliteit dienste aan die gemeenskap beskikbaar gestel.

Water word verskaf aan plase wat nie water het nie en plaaswerkers wie se huise deur die tornado beskadig is, word by die brandweersentrum gehuisves.

Werkers van die munisipaliteit het ook gister begin met opruiming in die Eden-hoewegebied. Bome en kragpale wat die naweek die pad versper het, is verwyder en inwoners het begin met herstelwerk aan hul huise.

Stefanie Jansen van Rensburg, woordvoerder van Eskom, het gesê tegnici is hard aan die werk om onderbreekte kragtoevoer na huishoudings te herstel.


- Die Burger Wes

'Tornado' beskadig 81 huise, kerk

Johannesburg – Een-en-tagtig huise en ‘n kerk is beskadig deur wat blykbaar ‘n tornado was in Kestel in die Vrystaat, het die provinsiale departement van samewerkende regering en tradisionele sake Maandag gesê.

“Die skade strek van afgewaaide dakke tot mure wat gedeeltelik ineengestort het,” het Senne Bogatsu, woordvoerder, in ‘n verklaring gesê.

Uit die beskadigde huise was nege HOP-huise, 11 was modderhuise, agt was sinkhuise en 62 was baksteenstrukture wat in private besit is.

Eskom-elektrisiteitspale is die enigste infrastruktuur wat beskadig is en elektrisiteit word stadig herstel na gebiede wat geraak word.

Plaaslike winkels het kos en klere aan dié in nood geskenk.

‘n Storm, wat deur sommige as ‘n tornado beskryf is, het Saterdag deur die gebied beweeg en erge skade aangerig.

‘n Verslag oor die skade sal na verwagting teen Dinsdag voltooi word, het Bogatsu gesê.


- SAPA/Nuus24

Questions: Tornado Outbreak: Free State Province (23 June 2012)

Image: Reitz Tornado - Hettie Steyn via Volksblad (Click on image for larger view.)

The SAWDOS received the following questions from our readers in view of this weekend's tornadoes. I would like to share my answers to these questions which might be of educational value to others.

1. Should South Africa be expecting any more tornadoes or any other disasters weather threats?

I am hesitant about making predictions about tornadoes, because — bar none — they are nature’s hardest weather event to predict.

That’s especially true of the most dangerous and destructive types of twisters, those classified as EF-5 and EF-4 on what meteorologists refer to as the five-point Enhanced Fujita Scale.

Tornadoes are essentially flukes of nature. Unlike other weather phenomena, they form spontaneously, are short-lived, and traverse a much smaller land mass by comparison.

Many atmospheric conditions need to converge at the right time for tornadoes to form. They need hot, humid air near the ground with a cool air mass above them. They also need strong wind velocity at higher altitudes, known as wind shear, to get them spinning

So I don't think every year is going to be as extreme and wild as this one. But I think the odds of those kind of years happening in the future will be steadily increasing.

Personally I am of the opinion that we can and will see some more tornadoes this coming storm season.

2. Why is it that people were not alerted of the tornadoes?

Throughout the world the timely issue of warnings for severe weather is critical to the protection of life and property, even more so for tornadoes. Nevertheless timely warnings remains very difficult. Severe weather events such as tornadoes can only be accurately predicted in situations where a storm or tornado already exists. Real time data such as radar, satellite, upper-air soundings and visual observations are of utmost importance once thunderstorm development has started.

Radar reflectivity values and the shape of the more intense cells can say much about the possibility for tornadoes to develop. Improved and timeous warnings of tornadoes can only be made if real-time observations and quality of radar data are available. This is where the SA Weather and Disaster Observation Service (SAWDOS) can play a very important roll in providing real-time observations to the general public. With an observer in the area of the storm valuable information can be gathered from real time observations to analyze the intensity and damage the storm caused.

The science of storm and tornado assessment relies on complex radar information and computer modeling, but witness accounts and painstaking inspections are equally important to create detailed maps of the path and extent of storms.

Tornadoes teach us humility. For all of the SA Weather Service scientific technology, they cannot issue tornado warnings. Without the help of the general public as severe weather observers there really isn't a thing they can do to warn those who are caught in a tornadoes path. The SAWDOS has nearly 300 real time observers out in the field that can send their observations to the SA Weather and Disaster Observation Service when severe weather or tornadoes occur providing that there is a weather observer in the area where the event occur. Tornadoes are conscienceless killers, coldly democratic in where and how they strike. The age of real time media has added a new and even more terrifying aspect: You can see the disaster forming then watch as it destroys.

3. Is climate change the reason behind the weather threats?

This is less clear: On the one hand, we would expect that a warmer climate would bring warmer temperatures and potentially warm moisture in the atmosphere, enhancing instability.

Instability is what happens when large masses of cold air in the atmosphere create updrafts, which can be up to 10 - 15 km high. These unstable conditions can lead to deadlier tornadoes. The jet stream plays a vital role. Climate change is expected to weaken the jet stream. And that's a key ingredient for making tornadoes. You need to have a really strong jet stream that changes velocity and speed with altitude in order to put a shearing force on those updrafts, to get them spinning, so that they become tornadoes. So it's unclear what's going to happen in the end.

In other words, the verdict is still not out on whether climate change will create more deadly tornadoes, and, at this time, there is no evidence that it will.

4. Are there any further weather threats that may effect further tornadoes in the Free State, Gauteng, Eastern Cape and Kwazulu Natal?

Severe weather and Tornadoes in South Africa can occur basically anywhere where a thunderstorm is possible. Tornadoes hit South Africa more than people would like to believe!! Analysis of tornadoes in South Africa reveal that the occurrence of tornadoes have been observed in Gauteng, Free State, Kwazulu Natal and parts of the Eastern Cape.

Most tornadoes events occur in mid-summer from November to January, although a large number of tornadoes have occurred in spring and early summer and in the late summer and autumn. Most tornado events occur in the late afternoon (16h00) or early evening.(19h00)

65% of South African tornadoes are classified as EF0 to EF1 (light damage) while more than 90% are classified as EF0, EF1 or EF2 (considerable damage) or less. A classified F4 tornado occurred near Mount Ayliff in the Eastern Cape on 18 January 1999. The tornado killed 21 people and injured 500 leaving hundreds homeless. The tornado had a track of 120 km long. The estimated wind speed of an EF4 tornado is between 350 - 400 km/h.

5. Natural disasters such as Tornadoes are not prone to South Africa, why is it that this occurred?

Tornadoes are small scale by-products of thunderstorms, with less then 1% of thunderstorms producing tornadoes. Until the middle of 1998 a general public perception prevailed that tornadoes do not occur in South Africa, but occur mostly in the USA. This perception seems to have changed during the 1998 - 1999 summer season when three damaging tornadoes occurred. These were named the Harrismith tornado (15/11/1998; F2 - F3), Mount Ayliff tornado (18/1/1999; F4) and the Umtata tornado. ( 15/12/1998; F2) Severe storms associated with extensive wind damage can, however, be erroneously reported as tornadic storms. An important point to remember is that a tornado's size is not necessarily an indication of its intensity. Large tornadoes can be weak and small tornadoes can be violent and vice versa. The life cycle of the tornado should also be taken into consideration. Damage varies from F0 to F5 with increasing numbers indicating increasing damage and therefor increasing intensity. The official estimate scale of a tornado is only made after the tornado has passed. The FP scale is, however, subjective and varies according to the degree of experience of the surveyor.

Tornadoes normally spawn from severe thunderstorms. Goliger et al. (1997) list the meteorological features necessary for tornado formation as, firstly, a deep layer of mid-atmospheric dry air above a moist surface; secondly, steep moisture and temperature gradients; thirdly, high surface temperature (not always a prerequisite as illustrated this weekend); fourthly, low-level convergence and upper-air divergence; fifthly, vertical wind shear; and lastly, atmospheric instability. Once you have the above conditions tornadoes can occur.

6. How many tornadoes formed this weekend in the Free State and what was the strength of the tornadoes that did touch down?

This is a million dollar question. I do not like to speculate, nor to make false statements. I will therefor just give my personal opinion after viewing nearly 100 photos and reading eye witness and media reports.

I would really be surprised if storms in the Reitz, Kestell, Bethlehem and Deneysville areas did not spawn tornadoes. I am of the opinion that there is enough "evidence" of a tornado in the Reitz area and I would allocate an EF2 strength to this specific tornado.

Unfortunately I do not have sufficient meteorological and other information at the time the severe weather developed and dissipated in the Kestell, Bethlehem and Deneysville areas. I cannot rule out the possibility that tornadoes moved through the Kestell and Deneysville areas. However the fact remain that severe thunderstorms (super-cells) did occur in these areas.

I trust that the above explain a bit more about tornadoes and that it might be of some educational value to our readers.

Regards

Johan Terblanche
Founder of the SA Weather and Disaster Observation Service (SAWDOS)
Mossel Bay
25 June 2012