We've had some intense rainfall today and were currently experiencing another burst right now. The upper trough/low is really producing some high rainfall rates around NSW. I noticed there were also some interesting storms out on the Central Tablelands and slopes yesterday. Love this kind of weather!

EDIT: A tornado was obseved by Greg Sorenson 20th January 2012

30 thought on “NSW Upper Low – Rain Storms and Tornado : 14-21 January 2012”
  1. The patterns have shifted and locked into East Coast onshore for the foreseeable future. A few rainfall totals approaching 100mm here in NE NSW though very patchy. A SWW for flash flooding was issued yesterday afternoon (15th) but cancelled this morning.  There is potential for heavy falls along parts of the coast depending on the position of the trough and if a coastal low forms.

  2. It would appear that the BoM has downgraded the potential for flooding now from this event and It remains to be seen what will transpire over the next few days with the presence of an inland surface trough and the models showing a return of a strengthening upper low.

  3. A nice cell has popped up south east of Goulburn and is heading north fast. It has a strong echo on radar and i can see knuckles on the back of the anvil from here! Wish I was down there.

  4. It’s now been severe warned and looks very nasty, big black core on it. Though it’s starting to lighten off a bit now

    The Bureau of Meteorology warns that, at 8:25 pm, severe thunderstorms were detected on weather radar near Wombeyan Caves and the Wombeyan Caves Road. These thunderstorms are moving towards the north. They are forecast to affect the area southwest of Yerranderie by 8:55 pm and the western parts of the Wollondilly Shire, the area west of Nattai and Yerranderie by 9:25 pm.

    Large hailstones, very heavy rainfall and possible flash flooding are likely.

  5. Jeff and Jary,

    That storm weakened and another developed in no man’s land to it’s w
    NW. From talking to David that second one looked more multicellular which is consistent with radar. The behaviour indicates that a boundary was on place and moving inland undercutting the first cell and eventually the second cell.

    Nice surprise. I guess when you have heating and high few points and a boundary then with a little cooling aloft, then I guess all you require is a boundary and a nice compact storm explodes.

    I am not around to chase so I hope others can do that.

    Jimmy Deguara

  6. According to the models we are now heading into a wet phase for the east coast with a very deep easterly flow looking to set in from Sunday and at one point the wind is easterly up to 300mb! An upper level cut off low will stall over the eastern interior and it even looks like a cut off low could form at the surface as well. Interestingly there is a deep and focused easterly jet appearing over the Hunter region next Monday/Tuesday which doesn’t bode well for potential wide scale flooding and rainfall total forcasts are looking high for many areas.  Storms will also be around but mostly inland for most of the week. Tomorrow looks interesting out on the Central Tablelands and I’d be chasing if I didn’t have another thing on. Damn it, you either have a life or you have stormchasing but it’ seems like you can’t have both. ;-)

  7. Just seen the images of the Tornado near Bredbo today and it looks like a real winner! The storm looked real nice on radar with evidence of a possible anti-cyclonic updraft with inflow in the south east quadrant. Can’t wait to see the footage as this looks like a real nice tornado and the footage is said to contain strong rotation! Wow i’m really pumped for that guy, it would’ve been awesome to see that and in one of my favorite spots near Tinderry Nature Reserve!

  8. Hi Jeff,

    It has awesome structure too – complete with tail cloud and inflow tail by the looks – the video of strong rotation leaves no doubt. This is the key – undeniable violent visible and clear rotation.

    Well done Greg. 15 years of chasing finally pays off with a surprise.


  9. Hi Michael,

    I wish to get hold of some higher quality video of this event. It certainly looks like a tornado however there is little or no rotation in the cloud in front of the funnel feature. Dynamically that does not make sense or is it the perspective. Very unclear unfortunately – I cannot tell. I hope we can see some original quality footage of the zoomed in component at least. All tornadoes I have seen in the US and Australia had violent rotation of the associated parent cloud and tornado even at a distance far more than this.

    Video still number 2 above caught my attention and seemed a little unusual as it was not smooth and tapered but given the statement of strong rotation I gave the benefit of the doubt. Given the video, I don’t see strong rotation in any part of the foreground cloud bases and features. I would like to see clearer imagery of the background funnel feature.

    Another observation is the cloud base becoming detatched from the main cloud base. This is quite common in higher regions when dew points are relatively high and cool outflow is present.

    Anyone going to do a damage survey?


    Jimmy Deguara

  10. I will put my word in and say that i think it is a tornado , contrast and distance make it hard to distinguish but i think it was on the ground for 30 seconds or so. As to the cloud in front it wasnt moving fast left to right but it was rolling horizontally quite well (low level NW inflow?). The wide angle lens doesnt help distinguish features tucked away under a storm like that.

    My congrats to Greg Sorenson for a great storm


  11. Hi Nick,

    Fair enough you ‘think’ it is a tornado – question is how will you enter it into a database – definite tornado? Scientifically speaking, we would do really like to see more evidence ie more high quality video. As to the wide angle lens – that shows an immediate disadvantage when picking out detail. I think the fact he was zoomed in, then that may have been sufficient given high quality video as for it was Youtube jerkiness that did not allow me to see motion within the funnel. Can you see rapid rotation Nick in the funnel as you have seen even from a distance in the US?

    We are definite this is a storm as we saw lightning. What else are we guaranteed here?


    Jimmy Deguara

  12. When I first viewed the video I thought, “where’s the rotation”. I was expecting surrounding clouds to really be on the move but they aren’t. However there still does appear to be a brief tornado in the sequence. The timelapse part helps to appreciate the normal speed view. The video looks quite decent in the 720p version.

    Greg was off to a damage survey this afternoon so that may help the discussion… or not.

  13. Hmm, I was expecting super strong wall cloud rotation after reading comments on another forum. I’ve watched it a few times now and i’m convinced that there is something dynamic happening in the area where he zooms in at 2:03-2:35, especially if you watch the cloud just above the hill. But it is inconclusive for me as the contrast is too flat to definitively make a definitive call. As for the storm itself, i’m almost convinced that we are not looking at anything super cellular either and the radar shows that at the stage of this video it was weakening rapidly. The strongest echoes were 20-30 minutes before this and any other severe features were likely best seen from the southern side going by the radar.

  14. Hi Nick,

    “As to the cloud in front it wasnt moving fast left to right but it was rolling horizontally quite well (low level NW inflow?)”

    NW inflow? I would have thought such inflow would have been too cool given the orientation of the storm.

    Jeff, you are correct regarding the’s weakening phase – the storm is definitely in breakdown with low level clouds become ‘disconnected’ or perhaps they were disconnected given the lack of rotation with the rest. Interestingly, it reveals a base which is significantly higher than the lower clouds and features in question in this discussion.


  15. Hi guys,

    I took another look at the video just now – twice actually when zoomed in. Am i right that it seems to be very slowly having motion right to left on the front of the feature – is that right? (my internet seems too slow). Even if there was motion, this means the ‘rotation’ if it does exist elbeit slow would be cyclonic – which is wierd given the southern right mover should be anticyclonic.

    I have said it several times now – tornadic rotation is unmistakeable. Even the weakest tornadoes have rapid rotation! This does not seem to be the case here.


  16. I think there is something in that feature from 2:05-2:30. Load the 720p version and roll backwards and forwards over the 25 seconds and you can see something thin and dark moving behind the feature to the right and you can just make out some kind of dark feature below it as well. You can just make out the tops of the highest hills there which reach 1,100m ASL so it’s possible if the lowering is directly over that area that it is interacting with the surface. The roll cloud in the middle appears to be rotating anti-cyclonically and the features on either side (the left one in the background being the suspect lowering) appear to be rotating cyclonically.  I also see evidence of some kind of clear slot like feature during the whole cycle.

  17. I’m undecided on wether it is a tornado or not… The thing that makes me lean towards it being unlikely is that on the youtube video, in the description he says he is 16km north of Bredbo looking south east… if you look at the radar archive (page 3 comments), the cell has a damn fine structure on the radar and at 4:00UTC a fairly hard to see hook, Which you only have to compare with google images to see a fair few radar images that are close to identical; this one looks most similar to me (comparison radar images are 4:00UTC and 4:10UTC).. Looking at this Id expect a tornado would be more likely to the west of Bredbo where it looks like there is a hook and a rather pronounced rear-flank gust front. Depending on where he was actually located while shooting the video, its either he is north west of bredbo looking south east at the area there would be a tornado (making it likely) or north of bredbo looking south east towards more of the front of the cell (making it unlikely) which is how I interpret it. At the end of the video in the 5x speed, it does look more like a tornado… Could the distance (I’d guess somewhere around 15-20km away; closer to the town of Bredbo going by the radar) cause the rapid motion detail to be more difficult to capture?

    Either way, I have no doubt in my mind that there was a high possibility for there to have been at least one tornado with this particular cell, I just don’t know whether he has caught it on video, or if it was unnoticed at a different location; but I wouldn’t be surprised if there was one.


  18. (still learning about all this stuff) Im just comparing it to the cooma-nimmitabel cell from 2008; this one looks similar to a northern hemisphere cell now that I am reading up a bit more (which would make sense, being the comparison picture is from Oklahoma).. The cooma-nimmitabel one had the hook in a different position I think… so most of my thoughts are probably incorrect in the previous comment… nevermind…

  19. Cameron said

    “Either way, I have no doubt in my mind that there was a high possibility for there to have been at least one tornado with this particular cell, I just don’t know whether he has caught it on video, or if it was unnoticed at a different location; but I wouldn’t be surprised if there was one.”

    No doubt? A hook is not always a guarantee there is a tornado “on the ground” although it is associated with a mesocyclone and associated structure.

    There may have been a tornado in or not in the video. However, what does the Bureau of Meteorology put in the database? Tornado, probable tornado, likely tornado, possible tornado… This is what I am leaning towards.

    A tornado was reported and it has filered through the media and amongst other chasers who simply congratulated him. Very few have questioned this report given the lack of clarity.

    A tornado report has to be verified based on evidence – debris cloud, damage, visual clues etc.


    Jimmy Deguara

  20. I’m confused with this one now!

    So the radar image above shows (let’s assume it is a hook echo) a storm that would have meso – anticyclone.  Looking at Greg’s summary on youtube he is positioned to the north west of the storm. The tornado (let’s assume the main feature is a tornado) is ahead of the precip, which wouldn’t make sense if it was associated with circulation producing the hook echo on radar (ie it would be behind that precip being wrapped around counter clockwise).

    So, we cant even conclude whether or not that’s a hook, despite the radar returns looking pretty good for that particular frame. We can conclude that if it was, Greg would not be in a position to see it as clearly as we see the feature in the video. I guess I am saying that the radar imagery does not support the presence of the tornado that is in the video.

    Disregarding radar and looking at the video.  There is a lack of discernible rotation in the cloud base and also in the lowered cloud features, there appears no organised rotation on the storm scale.  I’ve watched the timelapsed sequence several times and there is definitely some interesting motion and clearly some horizontal vorticity. If you take your eyes of the feature for a moment and look at how fast things are moving everywhere at 5X; or in otherwords, at 1X, how slow things are moving (both circulations that is). You would have to look at swirl ratios and the physics behind it, but it looks way to pedestrian to sustain a vortex funnel. It seems to me what we are looking at is the interaction of some horizontal convective rolls with the storm, particularly since the two circulations are kind of aligned but are counter-rotating. It is an interesting interaction for sure.

    I’m not saying this is the case here, but as a general comment here in Australia (where we get lots of storms but few tornadoes), chasers who have not seen a tornado with their own eyes don’t have a sense of how fast funnels are spinning and in the case of supercell tornadoes, how fast the wall cloud is rotating – you don’t need time-lapse if you are as close as this even with the weaker tornadoes!

  21. David said,

    “Looking at Greg’s summary on youtube he is positioned to the north west of the storm.”

    Ooops i guess I was thinking it was from the SE sorry Nick regarding NW inflow.

    However, it still does not change my view of this storm having a tornado. If this was the stronger cell – potentially left moving for those that think this was a supercell, then the features indicate it was not so strong and in a rapidly collapsing and weakening phase.


    Jimmy Deguara

  22. In reference to the 18th January storm


    I believe this storm had LP type structure. Unfortunately I was 20-30 kms on the wrong side to side to see much in the way of structure.


    Below is a video I took of the ‘no mans land” cell I as dubbed it.


    Ignore the first little bit, that is the remains of an earlier storm that had  a brief black core south of Marulan



  23. Michael T,

    Just took a look at your severe storm. Nicely structured with separation visible it seems. Excellent lightning bolts and behaviour – the pulsing behaviour means there was a decent updraft. Love the anvil crawlers as well!

    On another note, did you observe the storm with possible tornado near Bredbo? I am interested in your view of the feature in light of the recent video produced given you have experienced tornadoes in the US!


    Jimmy Deguara

  24. Gee that’s a very nice storm Michael, some savage CGs there, what  a pity the (lack of) roads didn’t let you get up close to see the structure.

  25. Jeff,

    I note you were going to head to to the region for work and checking for any possible damage within the National Park? Any word on that?

    Greg could ask come join if he wishes and post his report on the damage survey.


    Jimmy Deguara

  26. Jimmy,

    I’m heading down that way for work next week but at this stage i’m not sure i will have any time to have a detailed look around that area. I have a lot on and limited time.


  27. I drove past the spot on the Monaro Highway this morning and the first thing that struck me was the perspective. It’s not obvious in the photos posted but those photos are taken on an angle looking up so there is no guarantee that the distant object in the main image  is even touching the ground. I would estimate that the perspective would be at least 30 degrees above level. I will go back via the Bredbo-Braidwood road on my way home and see if I can spot anything. From the highway I could not spot any tree damage in any of the nearby hills.

    Update: I went back home via Jerangle and I looked around the area north east of Bredbo and there was no sign of any kind of storm damage anywhere at all, not even regular wind damage or flooding damage. I surveyed the southern side of the hills where it occurred with my 400mm telephoto lens and couldn’t find anything. If there was something on the ground it is more than likely that any trace of damage won’t be found. I could not get any access by road to the southern side due to private property. You might be able to get access from the north but i’m not sure it’s worth it.

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