Significant Tornado Events - Global Edition (2 Viewers)

MNTornadoGuy

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Does anybody know what in the world a "clear sky tornado" is? I've never heard of anything remotely like this, and I am honestly pretty skeptical if its even a real phenomenon. This posts claims it was equivalent to an F3. Not sure I buy that but interesting none the less.

Are they talking about a landspout?
 

OHWX97

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Does anybody know what in the world a "clear sky tornado" is? I've never heard of anything remotely like this, and I am honestly pretty skeptical if its even a real phenomenon. This posts claims it was equivalent to an F3. Not sure I buy that but interesting none the less.

What's got me scratching my head is the description of this phenomenon.
The phenomenon is actually a severe horizontal wind vortex with no visible condensation, associated with evaporative cooling of air due to virga from altocumulus and selective wavelength filtering of sunlight through particularly uniform cirrocumulus clouds. The vortex is tilted vertically by dense local fog layer breaking the capping inversion.
This obviously wouldn't be an actual tornado, but doesn't fit the description of a landspout, or dust devil, or just about anything I've ever heard of. It's baffling and a little frustrating because I've done a bit of digging around to find any other mention of such an occurrence, but unless I've missed something, it's only this Facebook post. Until I've seen this phenomenon acknowledged by an official source, I'm just as skeptical as you are.
 
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What's got me scratching my head is the description of this phenomenon.

This obviously wouldn't be an actual tornado, but doesn't fit the description of a landspout, or dust devil, or just about anything I've ever heard of. It's baffling and a little frustrating because I've done a bit of digging around to find any other mention of such an occurrence, but unless I've missed something, it's only this Facebook post. Until I've seen this phenomenon acknowledged by an official source, I'm just as skeptical as you are.
I've said it before: that sounds somewhat like what DePauw looked like at some points of its path (no visible condensation funnel but damage is still ocurring).
 

OHWX97

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I've said it before: that sounds somewhat like what DePauw looked like at some points of its path (no visible condensation funnel but damage is still ocurring).
The DePauw tornado developed from the mesocyclone of a parent supercell, making it a true tornado. The lack of condensation seen in photos was due to its massive, multiple-vortex structure. I didn't get the impression this "clear sky tornado" was associated with any thunderstorm.
 
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buckeye05

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"The phenomenon is actually a severe horizontal wind vortex with no visible condensation, associated with evaporative cooling of air due to virga from altocumulus and selective wavelength filtering of sunlight through particularly uniform cirrocumulus clouds. The vortex is tilted vertically by dense local fog layer breaking the capping inversion."

So basically an invisible tornado, like DePauw was for some parts of its life.
Everyone knows that some tornadoes lack a condensation funnel, but that isn't what's in question. Read the description of the alleged formation of this event. The post seems to be describing some kind of vortex that occurred independent of any kind of thunderstorm or mesocyclone.
 

TH2002

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Tornadoes are very rare in Iceland. The vast majority of reports in the ESWD database (excluding non-landfalling waterspouts) are reports of the tornado-like vortices that form from the ground up and connect to the base of pyrocumulonimbus clouds after volcanic eruptions. I'm on the fence as to whether these should be considered true tornadoes, as the way they form may actually have more in common with dust devils, but I'll leave that to open discussion. There is a dedicated thread for these volcanic eruption-induced vortices here: https://talkweather.com/threads/volcanic-tornadoes.1633/

But just because tornadoes are rare, that doesn't mean they haven't been observed. In August 2018, the country saw at least two true tornadoes spawned from thunderstorms. Even thunderstorm spawned tornadoes in Iceland are more often than not landspouts, though one of the storms that year was a true mesocyclonic tornado spawned from a supercell.

August 1, 2018 - Þorákshöfn
A landspout tornado touched down in rural areas, changing appearance several times during its lifecycle. The tornado did not impact any structures. It was estimated to have wind speeds of 30 meters per second (67 mph), making it an F0 tornado. For some reason this event is not listed in the ESWD database.
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August 24, 2018 - Norðurhjáleiga
A supercell thunderstorm spawned at least one tornado in south Iceland. Multiple funnel clouds were observed, and some locals reported that a second tornado touched down in the area. A farm sustained extensive damage, with seven outbuildings heavily damaged or destroyed. Roof panels were found 100+ meters away, and a 4x4 and attached trailer were overturned and thrown into a ditch. The damage was awarded an EF1 rating.
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