Should the terms waterspout, landspout etc be dropped?

[Sam Jowett]

Hi folks... possible baptism of fire here I suspect, but I promise I'm not trying to cause trouble. We've been having an interesting discussion on UKww regarding the relevance of using the terms waterspout, landspout etc when they're technically all tornadoes, so I was curious what you think. Please discuss it a bit first before voting... you might change you opinion...

To my mind, a tornado is any vortex induced by convection stretching boundary layer vorticity, including those on convergence zones, whether over land or water, under a meso or not. They are all produced by the same process, even if a meso will usually provide greater consistency and longevity, by virtue of the strength of the updraught and the fact it generates its own vorticity with the RFD.

Other problems with using terms like waterspout, seem to be when they come ashore. This is 1 meteorological event, but might be classified separately as both 1 waterspout and 1 tornado/landspout.

There also seems to be the misconception in the UK that waterspouts are weaker than tornadoes and filled with water. As many of our tornadoes are produced in autumn along cold fronts, the instability provided by the warm sea seems to mean waterspouts coming ashore are, on average, stronger than tornadoes generated inland. I'd guess this is less often the case in the US considering your geography. Education surrounding tornadoes is likely better in the US too, so misconceptions about waterspouts being filled with water are probably less common too.

The point still stands though, that a tornado is a tornado. Whilst there is a need to describe whether it is over water or land and the meteorological conditions surrounding the event, this can be done more accurately and clearly using 1 term I feel.

Reasons for continuing to use waterspout/landspout in the discussions I've had, seem to be centred around the sentimentality of simply being comfortable with the terms and enjoying having a variety of terms. Is this reason enough though if the multitude of terms creates confusion amongst the public? 1 meteorological phenomena only requires 1 term as far as I can see...

Would value your thoughts... will be interesting to see if the opinion here is any different to the UK

 

[Jeff Miller]

Terms

I have a multifacetted answer to this question.

There is one thing I am dead set against, and that is terming a true waterspout as a tornado, since true waterspouts are formed by a completely different mechanism only on water and dissipate before or just after making landfall. To term this sort of vortex as a tornado is a misnomer in my opinion.

Then the question arises about land-based vortices. I think that there should continue to be differences in classifications of vortices.

Landspouts are a land-based vortex, yes, and can be a KIND of tornado by definition only, and to the public, a tornado is a tornado. However, us in the weather circle recognize a landspout as a different form of tornado formed by a different process (not associated with a supercell mesocyclone). They can produce damage that is significant however, and the public does not need to have a distinction between a landspout tornado and a mesocyclone tornado. If it can cause damage, it is a tornado, and they need to take cover. My answer here would be who is the audience: The public or the weather weenies.

Gustnadoes are yet another type. The public, again, usually has never heard of such a thing. They have no clue where a tornado is supposed to originate. Watch any yahoo video clip and they will think a tornado or funnel is any lowering off of any storm cloud and flip out. Television markets would call a Gustnado a Tornado if it is confirmed so that the public is not confused and wonder what the heck a Gustnado is. For us in weather circles, we are well aware a Gustnado is simply a shallow eddy forming ahead of a strong gust front. To the public, it is a tornado. They don't need to know it is generally weak or we'd see yahoos having contests at who can get inside the gustnado and get mudblasted rather then seeking shelter.

In short, it depends on the audience. To the public (waterspouts excluded), call it a tornado, regardless of the type. To us in weather circles, the definitions are needed and necessarry because they give many clues concerning storm mode and tornadic type/function.

 

[Paul Knightley]

My view is that a tornado is a tornado, whether it forms over water, over land, beneath a towering cumulus, beneath a supercell updraught, etc. They are formed by the stretching of vertical vorticity, and the generic name should not need to differentiate between environments. It's confusing to the public, and rather pointless IMO.

Gustnadoes, thought, are definately not tornadoes, as they are merely swirls along a gustfront, without vertical stretching from above.

 

[Jeff Miller]

Gustnadoes, thought, are definately not tornadoes, as they are merely swirls along a gustfront, without vertical stretching from above.

Agreed. My point is, the public does not know that, or care. And because technically, a gustnado can be damaging, it still needs to be tornado warned if sighted.

 

[Tarmo Tanilsoo]

I would still like to have them as separate terms. I've seen from TV that waterspout looks totally different than a tornado... Though I have seen none of them with my own eye. But I agree about the warnings, they should be tornado warned. Unfortunately this would just be "a chance of twisters" on EMHI's warning page around here anyway so it would work out in countries like USA but not in Estonia.

 

[Sam Jowett]

Surely you assign terms for the vortex and the environment surrounding it separately though? A tornado over water may or may not be related to a supercell. If it's not, it will come ashore if the convergence zone and updraught producing it move ashore too. It's clearer to identify a vortex in terms of "tornado, over water, non meso" than "waterspout"/"true waterspout" I think... it's certainly more descriptive.

Despite being involved with severe weather, I'm not familiar with a definition for a "true waterspout". Is this produced by an updraught stretching vorticity too?

 

[Jeff Miller]

Definitions

True, or Fair Weather waterspout, is formed along lines of convergence with little windshear as a result or vortex stretching in the (mostly) developing stages of cumulus development. The True or Fair Weather waterspout is not related in any way shape or form to tornadic processes as would occur over land.

The Tornadic waterspout is basically a tornado developing over water formed by tornadic processes in association with a thunderstorm as would occur over land.

As far as calling it "tornado, over water, non-meso", I'm not sure what the purpose is since waterspout is such an accepted terminology with mariners and the general public alike, and, again, is formed by different processes altogether.

 

[Scott Olson]

Using the term landspout isn't necessarily implying that it isn't a tornado, instead it's just a simple term to describe the processes that led to formation. In research (it's primary use) it's almost always described as a landspout tornado or nonmesocyclone tornado. It's just a term Bluestein coined for describing the processes behind the tornadogenesis. The problem with waterspout has more to do with the definition of 'tornado' (violently rotating column of air) (pendant from cumulonimbus cloud). I'll certainly agree that tornadic waterspout is sort of a misnomer but changing it to 'tornado over water, mesocyclonic' just seems like semantics to me and doesn't accomplish anything. In the case of gustnadoes, unless we are talking about some freak event, I don't think they should be tor warned.

 

[Jeff Miller]

In the case of gustnadoes, unless we are talking about some freak event, I don't think they should be tor warned.

Hey Scott! Nice to see you.

please explain your reasoning behind this.

If a gustnado is sighted, I have heard many spotter/chaser reports calling in a gustnado (or simply a rotating debris whirl on the ground) and shortly therafter a TOR warning is issued. I also know Gustnado winds can approach 80 MPH which, in a Trailer park, can be devestating. If a Gustnado hits a trailer park, is it not possible for deaths to occur? And would it not be the fault of the NWS for failing to issue a TOR warn if such a scenario (albeit rare indeed) was to occur? No other warning covers this sort of event and at the wrong place at the wrong time - anything is possible.

 

[Martin North]

Evening Sam

I am glad that you have brought the arguement over here where is it almost certainly doomed to failure.

There is nothing wrong with using the term Landspout or Waterspout and you should not try to attempt to eradicate terms well recognised by chasers like me and others on here.

Fellow stormtrack members should feel free to read this thread on UKww where a voiciferous defense of these terms is being made by myself and others.

http://www.ukweatherworld.co.uk/forum/forums/thread-view.asp?tid=6820&start=1

You may even get a laugh ot two...

 

[Scott Olson]

Hi Jeff, I think you'd be hard pressed to find many offices that would issue a tornado warning for gustanadoes (what is recgnoized as gustanadoes). Certainly the winds can sometimes reach a damaging level but think about the duration, by the time the office gets the report it's likely already dissipated. There was one event earlier this year that involved some tornado warnings with what some thought were tornadoes, others thought were gustanadoes so FSD erred on the side of caution and issued a warning.

Hey Scott! Nice to see you.

please explain your reasoning behind this.

If a gustnado is sighted, I have heard many spotter/chaser reports calling in a gustnado (or simply a rotating debris whirl on the ground) and shortly therafter a TOR warning is issued. I also know Gustnado winds can approach 80 MPH which, in a Trailer park, can be devestating. If a Gustnado hits a trailer park, is it not possible for deaths to occur? And would it not be the fault of the NWS for failing to issue a TOR warn if such a scenario (albeit rare indeed) was to occur? No other warning covers this sort of event and at the wrong place at the wrong time - anything is possible.

 

[Jeff Snyder]

Jeff,

Re: tor-warnings for gustnadoes... Most gustnadoes are shallow and weak, thus making radar-warning difficult (if not impossible unless the area is very, very near the radar). They also aren't too uncommon along strong gust fronts. So, T warnings for such events would have a limited (or, likely, zero) lead-time for an event that typically lasts what, 10-20 seconds? Sure, 80mph winds in a gustnado can cause damage, but so can 80+mph straight-line winds. I'd go with a beefed-up SVR warning, and mention the possibility for short-lived, weak vorticies along the leading edge (I've seen warnings much like this, as well).

 

[Sam Jowett]

True, or Fair Weather waterspout, is formed along lines of convergence with little windshear as a result or vortex stretching in the (mostly) developing stages of cumulus development. The True or Fair Weather waterspout is not related in any way shape or form to tornadic processes as would occur over land.

If they're formed by different processes then it's fine to give them different names in my opinion, but how is the tornadogenisis thought to be different? I appreciate the larger parent environment will be very variable between situations, but that is described by whether the meso does or doesn't occur. I genuinely cannot see how a spout is any different from a tornado under a meso, other than in terms of its strength, longevity and parent environment. Can someone explain how it is?

 

[Sam Jowett]

Using the term landspout isn't necessarily implying that it isn't a tornado, instead it's just a simple term to describe the processes that led to formation. In research (it's primary use) it's almost always described as a landspout tornado or nonmesocyclone tornado. It's just a term Bluestein coined for describing the processes behind the tornadogenesis. The problem with waterspout has more to do with the definition of 'tornado' (violently rotating column of air) (pendant from cumulonimbus cloud). I'll certainly agree that tornadic waterspout is sort of a misnomer but changing it to 'tornado over water, mesocyclonic' just seems like semantics to me and doesn't accomplish anything. In the case of gustnadoes, unless we are talking about some freak event, I don't think they should be tor warned.

Interesting points Scott... it seems you have a clearer usage of the terms than we do in the UK. Here landspout tends to be used entirely separately from the word tornado, which created confusion amongst the media and public. This is why changing the terminology is more like semantics for you I guess. Clearly labelled sub-genre is much clearer than the situation we currently have. Mind you, I'd still go with "tornado-waterspout" rather than waterspout alone!

 

[Paul Knightley]

Surely tornadoes, whether forming beneath a mesocyclone or not, are formed from the stretching of vertical vorticity. Of course, there may be several different methods of generating such vorticity, but the end result is still a narrow vortex pendant from a cumuliform cloud, a tornado.

An example of confusing nomenclature occurred with the El Reno tornadoes, this past April. Some were classifying the second as a "landspout" - IMO, it was just a second tornado.

Granted it was not beneath the mesocyclone, but what should that matter? It still formed in the same manner, IMO, as the 1st tornado, it's just that its vorticity was derived from the other "side" of the RFD, and the stretching occurred beneath the flanking line (what what I can gather).