Social media was abuzz the week before last, with what residents described as a suspected “tornado” hitting the Seaview/Beachview area.
Whenever there is a severe wind event, the go-to phrase will always be tornado, though straight line winds can cause similar damage with winds reaching up to 180km/h.
In this case there was some limited, isolated damage and a funnel cloud of sorts was reported to have been seen.
Hence the public’s logic of associating the funnel cloud and damage with a tornado.
Firstly, for the record, without going into long scientific explanations, the chances of a full-blown tornado, a hurricane or snow occurring in the Bay or surrounds, are almost zero.
The meteorological conditions are just not conducive for such events.
Neither is there any chance of a “Sharknado”, as that is Hollywood fiction invented in that B-rated movie that the children loved so much.
The previously reported tornadic events in the Bay were incorrectly identified and were more than likely landspouts, which form under different conditions.
They occurred in 1978 (Mount Pleasant) and one in 2000 (New Brighton area).
These events were more than likely landspouts, which is a relatively new term, created by Howard B Bluestein in 1985 and used to describe a “tornado” not associated with a mesocyclone.
In other words, it is weaker than a tornado that spawned from a supercell.
The science behind the formation of a landspout and tornado are different.
Waterspouts are not rare and since the advent of cellphone cameras, more and more waterspouts have been photographed throughout the world, including the Seaview/Beachview area.
In other words, with more people around, all equipped with a cellphone, the chances of capturing these events have increased.
There are two types of waterspouts, namely tornadic and fair-weather varieties.
The tornadic variety is spawned from a supercell and generally forms in the rotating updraft of a thunderstorm.
Waterspouts are the cousin of landspouts which form in the growing stage of a thunderstorm that does not have a rotating updraft.
The biggest similarity is that unlike tornadoes, they form from the surface up.
The conditions on the day of the Seaview/Beachview event were ideal for the formation of waterspouts.
With the rising air off the relatively warm ocean, the passing cold front caused a thermal contrast (temperature difference), leading to some rotation in the atmosphere thus leading to the formation of a waterspout.
Though there was limited damage, according to photographic evidence, this is rare as waterspouts usually quickly dissipate when they make landfall.
Then we get other closely related atmospheric phenomena such as whirlwinds, dust devils, ash devils, snow devils and firestorms/whirls, which cause little to no damage, unlike tornadoes that can flatten entire suburbs.
A downburst, microburst, gust front, squall, gustnado, derecho are all terms for types of straight-line winds.
The major difference between straight-line winds and tornadic activity is that with tornadoes there is evidence of a twisting action on damage caused, as opposed to damage being caused in one direction/a straight line.
Just like a tornado, these straight-line winds are not only destructive but also pose a real risk to aviation and have been the cause of numerous aviation tragedies.
On the water front, the latest seasonal forecast is a bit indifferent with no promise of good rains going forward.
As we start moving out of the dry season into the wet season, starting in March, we are still in a good position, as far as our dams are concerned.
The Algoa Dam system (our main supply dams) is sitting at just under 80%.
This is the best position we have been in at this stage of the year, since the drought began.
It’s a pity that the metro has still not rewarded us and is keeping us on strict water restrictions, even though tariffs have ever so slightly been reduced.
With a January yielding almost double the rainfall of December at between 20 and 40mm in different parts of the city, my water tanks are doing their job.
I am one of the lucky ones being able to fill my pool and keep my prized petunias watered, legally.
This week in history
1981: The floods in Laingsburg are considered one of the greatest natural disasters in the history of SA when 104 people drowned and only 21 homes escaped damage. Who would imagine a similar event would occur in the Bay two months later in that year.
Dam Levels
Down from 80.21% to 79.07, with Impofu at 57.9%
Weather Safety Tips:
If any twisting weather phenomenon (tornado) is approaching you, run left or right, in other words 90 degrees of the direction it is moving in.
Now on Facebook, Instagram, and Twitter: WEATHER GURU
E-mail garthsampson59@gmail.com with feedback or requests
The Herald
WEATHER GURU | Whirly winds, dust devils, waterspouts and a ‘Sharknado’
Image: Supplied
Social media was abuzz the week before last, with what residents described as a suspected “tornado” hitting the Seaview/Beachview area.
Whenever there is a severe wind event, the go-to phrase will always be tornado, though straight line winds can cause similar damage with winds reaching up to 180km/h.
In this case there was some limited, isolated damage and a funnel cloud of sorts was reported to have been seen.
Hence the public’s logic of associating the funnel cloud and damage with a tornado.
Firstly, for the record, without going into long scientific explanations, the chances of a full-blown tornado, a hurricane or snow occurring in the Bay or surrounds, are almost zero.
The meteorological conditions are just not conducive for such events.
Neither is there any chance of a “Sharknado”, as that is Hollywood fiction invented in that B-rated movie that the children loved so much.
The previously reported tornadic events in the Bay were incorrectly identified and were more than likely landspouts, which form under different conditions.
They occurred in 1978 (Mount Pleasant) and one in 2000 (New Brighton area).
These events were more than likely landspouts, which is a relatively new term, created by Howard B Bluestein in 1985 and used to describe a “tornado” not associated with a mesocyclone.
In other words, it is weaker than a tornado that spawned from a supercell.
The science behind the formation of a landspout and tornado are different.
Waterspouts are not rare and since the advent of cellphone cameras, more and more waterspouts have been photographed throughout the world, including the Seaview/Beachview area.
In other words, with more people around, all equipped with a cellphone, the chances of capturing these events have increased.
There are two types of waterspouts, namely tornadic and fair-weather varieties.
The tornadic variety is spawned from a supercell and generally forms in the rotating updraft of a thunderstorm.
Waterspouts are the cousin of landspouts which form in the growing stage of a thunderstorm that does not have a rotating updraft.
The biggest similarity is that unlike tornadoes, they form from the surface up.
The conditions on the day of the Seaview/Beachview event were ideal for the formation of waterspouts.
With the rising air off the relatively warm ocean, the passing cold front caused a thermal contrast (temperature difference), leading to some rotation in the atmosphere thus leading to the formation of a waterspout.
Though there was limited damage, according to photographic evidence, this is rare as waterspouts usually quickly dissipate when they make landfall.
Then we get other closely related atmospheric phenomena such as whirlwinds, dust devils, ash devils, snow devils and firestorms/whirls, which cause little to no damage, unlike tornadoes that can flatten entire suburbs.
A downburst, microburst, gust front, squall, gustnado, derecho are all terms for types of straight-line winds.
The major difference between straight-line winds and tornadic activity is that with tornadoes there is evidence of a twisting action on damage caused, as opposed to damage being caused in one direction/a straight line.
Just like a tornado, these straight-line winds are not only destructive but also pose a real risk to aviation and have been the cause of numerous aviation tragedies.
On the water front, the latest seasonal forecast is a bit indifferent with no promise of good rains going forward.
As we start moving out of the dry season into the wet season, starting in March, we are still in a good position, as far as our dams are concerned.
The Algoa Dam system (our main supply dams) is sitting at just under 80%.
This is the best position we have been in at this stage of the year, since the drought began.
It’s a pity that the metro has still not rewarded us and is keeping us on strict water restrictions, even though tariffs have ever so slightly been reduced.
With a January yielding almost double the rainfall of December at between 20 and 40mm in different parts of the city, my water tanks are doing their job.
I am one of the lucky ones being able to fill my pool and keep my prized petunias watered, legally.
This week in history
1981: The floods in Laingsburg are considered one of the greatest natural disasters in the history of SA when 104 people drowned and only 21 homes escaped damage. Who would imagine a similar event would occur in the Bay two months later in that year.
Dam Levels
Down from 80.21% to 79.07, with Impofu at 57.9%
Weather Safety Tips:
If any twisting weather phenomenon (tornado) is approaching you, run left or right, in other words 90 degrees of the direction it is moving in.
Now on Facebook, Instagram, and Twitter: WEATHER GURU
E-mail garthsampson59@gmail.com with feedback or requests
The Herald
Would you like to comment on this article?
Register (it's quick and free) or sign in now.
Please read our Comment Policy before commenting.
Latest Videos
Most Read
Opinion
Opinion
Opinion
Opinion
Opinion