Kiama and Gerroa tornadoes 24 February 2013

tornado

A number of tornadoes have been confirmed by the BoM:

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21 thoughts on “Kiama and Gerroa tornadoes 24 February 2013

  1. Jimmy Deguara

    Interestingly, Jeff and I had a conversation about the use of Doppler being shadowed by the escarpment say near Albion Park though I don't think there is much if an issue along the coastline at Kiama.

  2. Stephen Jarrett

    Definitely not Waterspouts Jimmy, the conditions bred a rather intense RFD which swept down the coast from that line, the damage indicated is anywhere from EF0 – EF2 with that particular track looking EF2 and that one looks to be the most long lived out of the outbreak with Albion Park Rail – Jamberoo, Kiama and South of Gerroa all sharing tornadoes on this evening, I was on this line but the precip to me ended up making things way too risky to continue, these Tornadoes would have been extensively rain wrapped and no-one would have seen them coming!

  3. Jimmy Deguara

    –> Definitely not Waterspouts Jimmy, the conditions bred a rather intense RFD which swept down the coast from that line

    Ok fair enough I read the article from the Bureau – and specifically Andrew Treloar. By definition tornadoes on water are waterspouts. Of course the dynamics are different though! Any Doppler images from this event showing some form of couplets?

    I had my friend Daniel call the Bureau and he was told from ‘someone’ in the Bureau that there were no tornadoes just microbursts!

    Regards,

    Jimmy Deguara

  4. Jimmy Deguara

    It seems the dynamics were indicative of the type of ‘tornadoes’ experienced in La Perouse a few years back when a fast moving tornado occurred over the water and clearly on the boundary. Here are the respective images and videos of the associated event. I think this tornado was referred to as a supercell – low topped in the article?

    A COOL-SEASON LOW-TOPPED SUPERCELL TORNADO EVENT NEAR SYDNEY, AUSTRALIA
    Harald Richter*
    Bureau of Meteorology Training Centre, Melbourne, Australia

    La Perouse Tornado

    La Perouse Tornado Video

  5. Jeff Brislane

    I don’t understand what you mean when you say the conditions produced a Rear Flank Downdraft that swept down the coast. As far as I know Rear Flank Downdrafts are a phenomenan only seen with supercell thunderstorms. Are you saying this was a supercell thunderstorm that came onshore?

  6. Jeff Brislane

    I don’t understand what you mean when you say the system produced a Rear Flank Downdraft that swept down the coast. As far as I know Rear Flank Downdrafts are a phenomenan only seen with supercell thunderstorms. Are you saying this was a supercell thunderstorm that came onshore?

  7. Jeff Brislane

    I read Andrew Treloars comments and he seems to suggest that waterspouts do damage nowhere near as bad as this so this even must have been tornadoes and not waterspouts. wasn’t the Lennox head event a waterspout? It was rated F2 and I know waterspouts can easily reach F2 intensity so I don’t know what he is talking about (and I’m not sure he does either?)

  8. Jimmy Deguara

    Exactly my point Jeff. I think he has been misquoted! I am thinking this type of an event was related to something similar to the Lennox Head event and the one near La Perouse.

  9. Jimmy Deguara

    I think it was stated somewhere or inferred this was a ‘supercell’. The scale referred to on radar is totally off scale in comparison to a supercell. Note that Andrew Treloar does not mention the word supercell.

  10. Michael Bath Post author

    The Lennox Head tornado was from a supercell thunderstorm that just happened to initiate over water. Not just a typical waterspout. It was also associated with a larger scale coastal low pressure system with flooding.

  11. admin

    Yep Michael it seems to have had that type of structure. Was it low topped? If that was the case, it would have been similar to the case listed here at La Perpouse. My question here is the conditions if the events on the date of this specific south coast event occurred within the rain mess or from the individual cells that followed? I am in particular interested in this strong event coming in from the beach. For completeness sake, what is the name of this beach.

  12. Michael Bath Post author

    The Lennox Head one does not appear low topped from the satellite imagery of that morning (2nd June 2010)

    Check the satpic loop for current event (images will dissapear in time)

    http://realtime2.bsch.au.com/mtsat_sat.html?region=aus&loop=yes&images=&allday=&start=201302230433&stop=201302231833

    There is significant thunderstorm activity which formed off the MNC during the afternoon of 23rd. Had that been over land you’d certainly suspect possible supercell given the setup. The tornadoes appear to have occurred in a favourable area for the direction it is heading… effectively a right mover ?

  13. Jimmy Deguara

    Do you have any soundings by any chance from this event? That will provide a better measure of the clouds tops rather than relying on infra-red imagery during winter.

  14. Michael Bath Post author

    The assessment was from VIS images. Brisbane sounding is not indicative given the setup though tops would have been 30,000 feet.

    The topic we are looking at is the 24th Feb 2013 anyway….

  15. Jimmy Deguara

    Yes I know we are discussing 24th February tornadoes but we are just trying to get an understanding of the dynamics that caused them. A knowledge of the storms that caused them and the associated system definitely can help.

  16. Jeff Brislane

    What I was trying to get at in asking about this RFD that came down the coast is that Rear Flank Downdrafts are the products of individual storms and not whole storm systems. I asked why Stephen thinks it was a supercell that came onshore because i want to know where he thinks the supercell is on the radar imagery.

    In my opinion I think there likely three cells that could probably be classified as supercells from the radar signatures of this event. Now whether the tornadoes produced were from a meso-cyclone or not will probably never be fully known but what is known is that there were a number of tornadic touchdowns and at least one of them was in the vicinity of EF2 in intensity.

    What I do not like is definitive comments being thrown out into the discussion without any hard evidence to back them up. If they are definitely not waterspouts then tell us why and lets have a good discussion.

    Now lets get another thing straight, when we are talking about waterspouts we are not talking about “Fair Weather Waterspouts” that occur in gentle meteorological conditions. What we are talking about is the other type of waterspout that is produced by strong convective cumulus and cumulonimbus clouds. These types of waterspouts are the equivalent of the land-spout tornado that you see occurring from Thunderstorms and supercell thunderstorms but are not linked to a meso-cyclone. These types of tornadoes have been documented to have reached EF2 intensity.

    Regarding the Lennox Head event, maybe that would be better discussed somewhere else suffice to say that the Lennox Head cell produced two simultaneous tornadoes and I’m not convinced that either were the result of a meso-cyclone and if that is the case then it is not necessary for that cell to have been a supercell to have produced those tornadoes. Maybe there is other evidence out there that says otherwise but I haven’t seen it. Check out this YouTube video that shows both tornadoes.

    https://www.youtube.com/watch?v=J7YdiV0_AaU

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