tag:blogger.com,1999:blog-2399626414603781513.post3182429305697176883..comments2023-11-05T00:25:53.153-07:00Comments on Jon Davies Severe Weather Notes: An Essay: Gustnado or Tornado?Jon Davieshttp://www.blogger.com/profile/14044746324804312344noreply@blogger.comBlogger9125tag:blogger.com,1999:blog-2399626414603781513.post-69707123755269975072019-02-19T08:25:28.777-08:002019-02-19T08:25:28.777-08:00A bit late to the party but I'll throw my two ...A bit late to the party but I'll throw my two cents in here. <br /><br />The deciding factor is whether the vortex is connected to the storm updraft. You can definitely have tornadoes that form along the leading edge of outflow and are connected to the updraft region of the storm - in fact, this is the definition of a classic 'bow echo' tornado. Fujita depicts the tornado development well ahead of the storm's radar echoes, at the outflow / updraft interface.<br /><br />Which brings me to your diagram. What you label as your gustnado case is actually more similar to the scenario I described above.<br /><br />Gustnadoes do form along gust fronts but the difference is that they do not connect to the storm updraft, and are therefore confined to a shallow near-surface layer and are short-lived. It's also why they do not fit the definition of tornado. So your diagram should have a third panel with a shallow vortex forming well away from storm updraft region.<br /><br />Re waterspouts, any of the above processes can occur over water (supercell tornadogenesis as well). When it's a tornado over water, you can call it a waterspout. Doesn't matter how it formed. But when it's a gustnado over water, it's still just a gustnado over water.<br /><br />Dave SillsAnonymoushttps://www.blogger.com/profile/03564661286210643823noreply@blogger.comtag:blogger.com,1999:blog-2399626414603781513.post-10018187305149050962016-08-04T18:02:39.185-07:002016-08-04T18:02:39.185-07:00Gustnados are definitely tornados. I say that beca...Gustnados are definitely tornados. I say that because they occur on the gust front. The front side of a gust front is the updraft side and the back side is the downdraft side, with gustnados occurring on the updraft side. Just because the NWS cannot detect and measure them with current radar technology does not invalidate them as tornados since the knowledge does exist which proves they are tornados... a rotating column of air within an updraft is all that should be needed. However, the official definition of a tornado was re-written some time back to exclude such things as gustnados and the reason is because they're not large enough, destructive enough, nor long-lived enough to get meteorologists sitting in a boring NWS station excited. The meteorologists choose what they want to call a tornado based solely upon "does it excite me enough in some way" criteria, which is not the way of true meteorology. That's an absolutely absurd way to define things.Anonymoushttps://www.blogger.com/profile/02090485950858588243noreply@blogger.comtag:blogger.com,1999:blog-2399626414603781513.post-89370747395782707712011-04-15T22:49:59.688-07:002011-04-15T22:49:59.688-07:00Jon,
Nice writeup.
I wanted to add a little anec...Jon,<br /><br />Nice writeup.<br /><br />I wanted to add a little anecdote...<br /><br />Some years ago I witnessed a gustnado in the AZ desert which lasted at least 15 minutes, was ~100 meters in diameter, and was observed by others from 20 miles away (we conversed on Skywarn ham radio). But it was *clearly* not a tornado - it was miles from the nearest updraft, in clear air and bright sunlight.<br /><br />The desert helps make these things much more visible than in tornado alley.StormCchaserhttps://www.blogger.com/profile/02998174514362089471noreply@blogger.comtag:blogger.com,1999:blog-2399626414603781513.post-8630295593339841732011-04-07T12:52:28.135-07:002011-04-07T12:52:28.135-07:00Darin:
The whole tornado-labeling thing is certai...Darin:<br /><br />The whole tornado-labeling thing is certainly a problem for climo records. Most gustnadoes I've seen are indeed short-lived and very weak. But how do you label/categorize one that has 5-10 minutes continuity and does EF1 winds, not precisely fitting the AMS defintion? The whole categorization thing is needed for scientific documentation, but also presents problems.Jon Davieshttps://www.blogger.com/profile/14044746324804312344noreply@blogger.comtag:blogger.com,1999:blog-2399626414603781513.post-74004807736755258502011-04-07T12:45:57.116-07:002011-04-07T12:45:57.116-07:00Greg:
Point well taken. The El Reno case is prob...Greg:<br /><br />Point well taken. The El Reno case is probably not a good example to make my point, though the tornado did occur in a roughly similar location relative to the mesocyclone as Sunday's "vortex". I agree that we shouldn't categorize vortices by appearance, but more by the processes and ingredients that generate them. Thanks for the clarification and input.Jon Davieshttps://www.blogger.com/profile/14044746324804312344noreply@blogger.comtag:blogger.com,1999:blog-2399626414603781513.post-79664719475182862632011-04-07T12:32:18.829-07:002011-04-07T12:32:18.829-07:00Enjoyed the post! For those who are interested, h...Enjoyed the post! For those who are interested, here's the timelapse of the El Reno storm. I'll let you make your own conclusions. - Aaron <br /><br />http://www.youtube.com/watch?v=B4ty14Fbbm8A.K.https://www.blogger.com/profile/09992293656253142391noreply@blogger.comtag:blogger.com,1999:blog-2399626414603781513.post-30937375749299740192011-04-07T10:41:29.198-07:002011-04-07T10:41:29.198-07:00I think the biggest problem, no matter what is a t...I think the biggest problem, no matter what is a tornado or isn't a tornado, is that people are way to quick to leave it at the generalized term(adding in "non-mesocyclone" doesn't sound as good, maybe?). No matter if it's a waterspout, landspout, supercellular tornado, or any other variation people will automatically label it a tornado and leave it at that. Then many times the simple term "tornado" will end up making it into the NCDC database when it should be broken out in many ways IMO. That's terrible for long term climatology.Darinhttps://www.blogger.com/profile/05894128773329565773noreply@blogger.comtag:blogger.com,1999:blog-2399626414603781513.post-18757000603503593672011-04-07T10:02:19.491-07:002011-04-07T10:02:19.491-07:00Agreed, and as a corrolary to this, I hate seeing ...Agreed, and as a corrolary to this, I hate seeing the term "waterspout" used to reflect any tornadic circulation over water. A waterspout is analogous to Greg's landspout definition, and most commonly observed in the tropics (i.e. Florida, Carribean, etc..) due to sea breeze interactions or rapid heating and vertical stretching via towering Cu, most often observed during the late morning and early afternoon.<br /><br />If a supercell and tornado pass over a body of water, I would maintain that this is a "tornado over water" vs. a waterspout which has already been assigned a non-mesocyclone definition.<br /><br />I also agree that the presence of a condensation clouds wholly or partially visible to an observer should be stricken from this discussion.<br />-Evan BookbinderEvan Bookbinderhttps://www.blogger.com/profile/10589049011739459871noreply@blogger.comtag:blogger.com,1999:blog-2399626414603781513.post-78089622960993160382011-04-07T09:35:50.186-07:002011-04-07T09:35:50.186-07:00John, great writeup, as usual. However, I differ ...John, great writeup, as usual. However, I differ on your opinion of the El Reno vortex of 24 April 2006, since I was there to observe it. The tornado in the picture was actually an anticyclonic pair to another cyclonic tornado up closer to I-40. The pictured tornado was associated with the southern bookend of the horseshoe-shaped updraft and not a landspout. In fact, it was the stronger of the two tornadoes based on damage surveys.<br /><br />Also, we need to be careful about characterizing tornadoes based on their appearance. If a tornado is made visible only by a small condensation funnel and a long dust tube, it isn't automatically a landspout. Sure, that's how many landspouts appear on the High Plains, but many of the tornadoes along the sea-breeze convergence areas in Florida and along the Gulf Coast in summertime are also non-mesocyclone (landspouts). Those tornadoes occur in more-humid environments, and can easily have condensation funnels reaching the ground, even though they too are landspouts. And of course, there is the opposite - mesocyclone tornadoes that have short funnels and long dust tubes.<br /><br />-greg stumpfggggghttps://www.blogger.com/profile/17996117915672390142noreply@blogger.com