Talk:Annular tropical cyclone

Todo
The journal article is many pages long. Surely there is more information available. Jdorje 19:53, 9 January 2006 (UTC)

Picture?
How about a few satellite pictures to describe this type of hurricane?

What is an annular hurricane?
I'm no meteorologist, but to me the logic of annular hurricanes seems fairly simple.

In an average hurricane, there is a pretty even wind gradient between the eyewall (which has the strongest winds) and the outermost rainbands (which have weak winds but are still tropical in nature). As time passes, assuming the storm continues to be powered energy will be transferred outward from the eyewall into the outer rainbands. After the storm passes peak intensity, the eyewall will weaken quickly as it goes through eyewall cycles. This transfers kinetic energy (or angular momentum) into the outer rainbands, speeding them up. Thus it is not necessarily the case that a drop in eyewall winds corresponds to a drop in the destructiveness of the hurricane, if it just means that energy is being distributed over a larger area.

An annular hurricane has few or no outer rainbands, and the area covered by thunderstorms all has high winds. With no "outer rainbands" to speak of, there can be no eyewall replacement cycles and no way to transfer energy outward from the eyewall. Thus, after passing peak intensity these storms do not naturally "flatten" and only weaken as they lose energy to friction with the surface.

Someone added that Katrina, Emily, and Epsilon were annular hurricanes. I removed this since it needs to have a source. However, Katrina in particular is the exact opposite of an annular hurricane. It had hideously huge amounts of outer rainbands, and as it went through its eyewall replacement cycle just before landfall a massive amount of energy was transferred from the eyewall (which therefore weakened tremendously) to the outer rainbands. The end result was a giant massive hurricane.

It's also surely the case that "annular" is not just a characteristic, it is a range. You can't just say that a storm has or does not have outer rainbands, it is always a question of how many it has. Among historical storms, likely candidates for annular hurricanes are those that were small: Camille, Andrew, Charley. Among 2005 storms, I think you look on satellite and radar for storms that look like donuts: a massive eyewall and not much else. Just based on the radar images I saw, I'd guess Ophelia and Wilma (only after crossing the Yucatan Peninsula) are likely candidates.

— jdorje (talk) 20:08, 25 February 2006 (UTC)

Loop?
Here is an IR loop of Daniel, showing the classic 'donut-ring' convection typical of annular hurricanes ( from the Unisys Weather website ). This would make a great addition to the article.

I'm no expert at uploading images so if anyone can help, please do. Thanks! Pobbie Rarr 02:05, 22 July 2006 (UTC)


 * Sadly, I don't think Unisys' images are free...one would have to animate pictures from NRL, I guess. -- RattleMan 15:31, 22 July 2006 (UTC)


 * There's an animation of Katrina from here Good kitty 17:09, 23 July 2006 (UTC)


 * I don't think Katrina was annular though. Pobbie Rarr 20:36, 23 July 2006 (UTC)
 * I agree, look at that massive cloud bands extending from it's center (most of them well red, like normal hurricanes). Irfan  faiz  23:14, 4 August 2006 (UTC)

Image
If someone could find a good Infrared image of an Annular hurricane, that would be awesome. Runningonbrains 19:58, 23 July 2006 (UTC)

The external link to the article has a few good images. Anyway, why has the Isabel pinwheel image been removed? I thought it looked awesome. Pobbie Rarr 20:43, 23 July 2006 (UTC)
 * Free images, which could be used in this article, would be awesome, however...Runningonbrains

Rarity?
I haven't read the entire journal article in order, but I can't really figure out where the "less than 1% of Atlantic and 3% of East Pacific hurricanes" bit comes from. The best match I can find is Table #4 of the Knaff article (with the same numbers repeated twice in the text), which lists 0.8% and 3% respectively for Atlantic and East Pacific for how many storms have all 8 environmental conditions conducive to the formation of an annular hurricane. I think I am going to change this unless someone finds the source for the statement as-is. —AySz88\ ^ - ^ 00:56, 24 July 2006 (UTC)
 * You are correct, that statement is a misinterpretation of the findings. Would you mind fixing it so it is correctly worded? Runningonbrains 21:55, 24 July 2006 (UTC)

From what I have seen and heard, Hurricane Epsilon was indeed an annular hurricane. Annular hurricanes are known to be able to survive in conditions that would flatten a normal hurricane, showing very little variation in strength. Epsilon was able to persist for days on end with very little variation in its strength, and actually if you look at some videos of it, you can see where there were very few outside rain bands on it, it was a small storm, and there was never and eye wall replacement cycle. However, most, if not all, annular hurricanes are only annular for a portion of their life, like in the case of Epsilon. Towards the end of its life, you can see where the outflow began to form, and later that night, the storm weakened to a minimal tropical storm, and later dissipated that day. —Preceding unsigned comment added by 74.160.83.146 (talk) 22:59, 26 April 2011 (UTC)


 * Yeah, Epsilon was annular, same with Katrina, and Wilma after a while. 98.122.7.213 (talk) 01:11, 23 November 2022 (UTC)
 * Neither Katrina nor Wilma showed annular characteristics, nor is that mentioned anywhere in their Tropical Cyclone Reports. 🌀CycloneFootball71🏈 |sandbox 16:21, 23 November 2022 (UTC)

Annular typhoon?
Is there any typhoons that has a structure similar to an annular hurricane? Irfanfaiz 13:29, 24 July 2006 (UTC)
 * No studies that I have heard of have studied storms outside of the Atlantic or East Pacific basins, so the term has only been referred to as "annular hurricane". Once research is done outside of these basins, this article will undoubtedly have to be moved to Annular tropical cyclone.  I'm quite sure that they do exist outside of these basins, but we can only use official sources, not my feelings. Runningonbrains 21:56, 24 July 2006 (UTC)
 * This looks familiar? http://earthobservatory.nasa.gov/NaturalHazards/Archive/Oct2005/Longwang.A2005274.0505.jpg Irfanfaiz 02:49, 29 July 2006 (UTC)
 * This dear resambles an "annular typhoon" near peak intensity. Typhoon Rusa Irfan  faiz  06:39, 3 August 2006 (UTC)

From what I have seen and heard, Hurricane Epsilon was indeed an annular hurricane. Annular hurricanes are known to be able to survive in conditions that would flatten a normal hurricane. It also showed very little variation in strength. Epsilon was able to persist for days on end with very little variation in its strength, and actually if you look at some videos of it, you can see where there were very few outside rain bands on it, it was a small storm, and there was never and eye wall replacement cycle. However, most, if not all, annular hurricanes are only annular for a portion of their life, like in the case of Epsilon. Towards the end of its life, you can see where the outflow began to form, and later that night, the storm weakened to a minimal tropical storm, and later dissipated that day. —Preceding unsigned comment added by 74.160.83.146 (talk) 23:00, 26 April 2011 (UTC)

Technical language
Some of the conditions associated with annular hurricanes are: An intensity 85% or greater from their theoretical maximum potential intensity, weak wind shear from the east or southeast, a cold east wind at a high altitude (the 200 mbar pressure level), near-constant sea surface temperatures between 25.4 °C and 28.5 °C, and lack of relative eddy flux convergence at the 200 mbar pressure level, relative to the storm.

Stuff like this means very little to the layman. Can someone rephrase the technical mumbo-jumbo into prose that most people can understand? Runningonbrains 04:52, 26 July 2006 (UTC)


 * There's only one thing on there the average smart person who knows something about tropical cyclones shouldn't be able to understand, and that's the relative eddy flux convergence/200mb level thing (I have no clue what a relative eddy flux convergence is, and there's no article on it). That's the only sentence that really needs to be rewritten. bob rulz 02:42, 27 July 2006 (UTC)


 * I (who added that) already de-technicalized most of it (at least compared to the journal article), but I don't know what an REFC is either, so I didn't try to simplify that one. (Relatedly, I'm not sure why there's no article on pressure level yet either, since that concept is encountered all the time in meteorology, I think.)
 * Those environmental conditions are all rather bizarre (things you wouldn't really associate with why the thing looks like a donut), so it's hard to rephrase any further unless there's some way to make an analogy of some kind, which we can't really do because our article doesn't really give much information. —AySz88\ ^ - ^ 02:53, 27 July 2006 (UTC)

List?
Would creating a list of annular hurricanes at List of annular hurricanes be feasible? I think it would be interesting to know that, so would it be possible for it to be done, or does the "significant annular hurricanes" section pretty much cover all of the known ones? bob rulz 02:42, 27 July 2006 (UTC)


 * The only ones we can officially certify as annular are the very recent ones described as such by the NHC (like Epsilon and Daniel). There are several likely candidates for annular status from yesteryear, but I don't think we can claim it as a fact unless a source such as the NHC says so. Therefore, any list we could make right now would have to be very small indeed. Pobbie Rarr 23:01, 27 July 2006 (UTC)


 * Well, don't forget we also have six from the Knaff article that's being used (how'd they manage to write a paper with only six examples?): Hurricane Luis, Hurricane Edouard (1996), Hurricane Darby (1998) (not mentioned in the season article), Hurricane Howard (1998) (not mentioned in the season article), Hurricane Beatriz (1999), and Hurricane Dora. —AySz88\ ^ - ^ 23:29, 27 July 2006 (UTC)


 * It has some encyclopaedic value...I say go ahead. We can start with the Knaff storms, and then add them as we see them in NHC TCRs.  Runningonbrains 02:05, 28 July 2006 (UTC)

Origins of annular hurricanes?
Although we obviously don't know for sure why certain hurricanes become annular, perhaps [http://www.nhc.noaa.gov/archive/2006/dis/ep052006.discus.013.shtml? this NHC discussion] of Hurricane Daniel might help. It anticipated Daniel becoming annular: FORECAST ENVIRONMENTAL CONDITIONS OF LIGHT EASTERLY SHEAR AND SLOWLY DECREASING WATER TEMPERATURES BELOW 28C ALSO SUGGEST THAN THE HURRICANE COULD BECOME AN ANNULAR-TYPE SYSTEM OVER THE NEXT DAY OR SO.

Basically, shear was light in the direction of Daniel's motion and SSTs were mildy favourable for sustenance. I wonder if the NHC will devote a section to annular hurricanes some time soon. Pobbie Rarr 15:26, 24 August 2006 (UTC)

Lede photo
While I do agree the current image is pretty good, the one added by User:Good kitty (Image:Isabel-eyewall-091203.jpg) was better, showing more detail of Isabel's classic annular structure, and without the distracting text imbedded in the image itself. Thoughts? -Runningonbrains 04:37, 28 September 2006 (UTC)
 * I disagree. The Isabel pinwheel eye image is as annular as a hurricane can get. Just my $0.02 of course. Pobbie Rarr 14:52, 28 September 2006 (UTC)
 * The other one I found also showed a pinwheel eye. However the article doesn't even define "pinwheel eye" Good kitty 02:05, 4 February 2007 (UTC)

Rarity revisited
That seems like an awful lot of examples for something that's only supposed to happen once every 100 hurricanes (1% frequency). Mdotley 16:49, 3 October 2006 (UTC)

OK, I reread it again, and it doesn't actually SAY they occur at that frequency, but it darn well implies it. If that's not what we want ppl to take away from that paragraph, then the relationship between favorable conditions and actual annularity needs to be spelled out a bit more, (even if it's to say that we don't know exactly how they're related). Mdotley 16:52, 3 October 2006 (UTC)

Cyclone Dora
MICROWAVE IMAGERY HAS SHOWN AN IMPRESSIVE ANNULAR CYCLONE WHICH DEEP CONVECTION HAS BECOME COOLER AND EYE WARMER IMAGE AFTER IMAGE (AMSU 0909S) 
 * Dora has a structure of an annular cyclone, with the typical big eye no rain bands. Is this the first tropical cyclone to be annular except for the Atlantic hurricane and Eastern pacific basins? -- Irfan Faiz  02:25, 3 February 2007 (UTC)
 * There must have been annular tropical cyclones in the Indian Ocean before Dora: the study of the phenomenon is still very new. Interestingly, Hurricane Dora of 1999 (E.Pac) was also annular. Pobbie Rarr 02:48, 3 February 2007 (UTC)
 * Another Dora... also annular.... a coincidence. -- Irfan Faiz  07:06, 3 February 2007 (UTC)
 * It may be worth looking into the history of annular tropical cyclones outside of the Atlantic and Eastern Pacific basins, because if they've occurred there before (and there is adequate documentation - they probably have, there just may not be any info), this article may need to be moved to something like Annular tropical cyclone or something along those lines. --Core desat  07:43, 3 February 2007 (UTC)
 * Just a thought, would moving the page to a name such as Annularity be better than trying to think of an ambiguous noun to tack on the end of the word annular? - RunningOnBrains  &mdash;   Mine   Yours   Someone else's  23:23, 3 February 2007 (UTC)
 * Thats not sensible; annularity is a bad noun form of Annular. An article at that location should be a dab, you would end up with Annularity (meteorology) or something like that... Annular tropical cyclone (or maybe Annular cyclone) makes more sense.--Nilfanion (talk) 23:31, 3 February 2007 (UTC)
 * If Dora is annular, maybe tropical cyclones with an annular structure are common other than the Atlantic and Eastern Pacific hurricane basins? I give Longwang as an example, i saw it's track map and it maintained Category 4 intensity for almost half of it's track. I saw the image and i found out it had a large eye and a few rainbands. -- Irfan Faiz  10:02, 4 February 2007 (UTC)

Nida and Wilma
Hi. Were Typhoon Nida (2009) and Hurricane Wilma annular hurricanes? Thanks. ~ A H  1 (TCU) 22:20, 31 August 2010 (UTC)
 * From what I can tell, no, neither of those storms were annular. However, Hurricane Irma was an annular storm, as were many of the powerful super typhoons from 2018.  Light and Dark2000  🌀 (talk) 05:39, 18 May 2019 (UTC)

Hurricane Catarina
Could it be listed here as an annular hurricane? It looks like one to me, and it would explain why one would persist in the South Atlantic and not weaken. I've always thought of Catarina as similar to Epsilon in form. Cyclone Catarina UltimateDarkloid (talk) 19:46, 14 November 2010 (UTC)
 * Not without verification from a credible source. That is a reasonable proposal, but unfortunately I can't find anything to support it after an immediate Google search. Cucurbitaceae (talk) 21:45, 14 November 2010 (UTC)

Citation help
I have added several hurricanes that were considered annular according to and article in the AMS Journal called 'Objective Identification of Annular Hurricanes' and I don't know how to cite it on wikipedia. Stormchaser89 (talk) 5:45, 21 July 2011 (US Central)

Partially explains, not really
In the article: "Hurricane Epsilon of the 2005 Atlantic hurricane season had a similar structure to an annular hurricane, which partially explains the storm's longevity in the face of unfavorable conditions." -- I don't think it really "explains" anything, since, as far as I can see, it's not exactly clear why annular hurricanes form or persist like they do. 172.130.139.99 (talk) 22:35, 3 August 2011 (UTC)