Author Topic: Australian tornado climatology and information / Bulahdelah Tornado Report 1/1/1970  (Read 17910 times)

0 Members and 1 Guest are viewing this topic.

Offline Jimmy Deguara

  • Australian and Tornado Alley storm chaser
  • Administrator
  • Wedge tornado F5
  • *
  • Posts: 2,218
  • Gender: Male
  • Storm Chaser since 1993, Tornado Alley 2001
    • Australia Severe Weather
Hi,

Whilst perusing the internet in search of particular facts about tornadoes, I came across these resources which is quite interesting given it is wikipedia. Including is a table of tornado information and links:

http://en.wikipedia.org/wiki/List_of_Southern_Hemisphere_tornadoes_and_tornado_outbreaks

http://en.wikipedia.org/wiki/Bulahdelah_tornado

There are of course links to other segments from the original link above.

Regards,

Jimmy Deguara
-------------------------------------
Australian Severe Weather
www.australiasevereweather.com

Australian Thunderbolt Tours
www.thunderbolttours.com

Phone  0408 020468  (International :  61  2  408 020468)

Offline Michael Bath

  • storm chaser
  • Administrator
  • Wedge tornado F5
  • *
  • Posts: 1,602
  • Gender: Male
    • Australian Severe Weather
I came across this as well the other day when looking up the dates for a couple of the other major events.

There was no info that I could find about the time the Bulahdelah tornado occurred. After plotting charts from the GFS archives it appears to have occurred between 00z and 06z. Pretty impressive getting such cold upper air at the beginning of January.

There are no satpics or soundings available (online) this far back in time for Australia.

01/01/1970 00z

Instability: Lifted Index

Relative Humidity: 0300 / 0500 / 0600 / 0700 / 0850 / 1000

Temperature: 0300 / 0500 / 07000850 / 1000

Winds (knots): 0300 / 0500 / 0600 / 0700 / 0850 / 0925 / 1000


01/01/1970 06z

Instability: Lifted Index

Relative Humidity: 0300 / 0500 / 0600 / 0700 / 0850 / 1000

Temperature: 0300 / 0500 / 07000850 / 1000

Winds (knots): 0300 / 0500 / 0600 / 0700 / 0850 / 0925 / 1000


Location: Mcleans Ridges, NSW Northern Rivers
Australian Severe Weather:   http://australiasevereweather.com/
Lightning Photography:   http://www.lightningphotography.com/
Early Warning Network: http://www.ewn.com.au
Contact: Michael Bath

Offline Jimmy Deguara

  • Australian and Tornado Alley storm chaser
  • Administrator
  • Wedge tornado F5
  • *
  • Posts: 2,218
  • Gender: Male
  • Storm Chaser since 1993, Tornado Alley 2001
    • Australia Severe Weather
Michael,

What I find interesting about the year 1970 was that it was from what I recall statistically a cold winter - Richmond for instance acheieved its coldest morning on record of -8.3C. I assume that particularly cold air was advected north and perhaps made such a cut off low with such extreme temperatures possible that year.

That was one hell of a system!

Regards,

Jimmy Deguara
-------------------------------------
Australian Severe Weather
www.australiasevereweather.com

Australian Thunderbolt Tours
www.thunderbolttours.com

Phone  0408 020468  (International :  61  2  408 020468)

Offline James

  • Elephant Trunk F2
  • *
  • Posts: 149
  • Gender: Male
    • Sydney Storm Chasers

Wow, that is a nice set-up alright! Thanks for digging out those links above MB.

A couple of things caught my eye looking over those charts above. I would have thought the RH for 1000 and 850 would have been a little higher than around 50%. Is there any record of the LCL for that day? Probably not but thought I'd ask. Second thing is watching the surface low really develop between 00z and 06z. Quite awesome to see it take shape with increasing wind speeds around it as the upper cold pool approaches.


Offline Jimmy Deguara

  • Australian and Tornado Alley storm chaser
  • Administrator
  • Wedge tornado F5
  • *
  • Posts: 2,218
  • Gender: Male
  • Storm Chaser since 1993, Tornado Alley 2001
    • Australia Severe Weather
Hi James,

I have seen the actual report of this event and let me tell you the analysis was reasonably complex with a surface trough along the eastern part of the ranges. Supercells exploded along the line with cricket balls sized hail amongst a few of the storms. This storm for some reason developed very low bases and thence the giant tornado that followed!

Regards,

Jimmy Deguara
-------------------------------------
Australian Severe Weather
www.australiasevereweather.com

Australian Thunderbolt Tours
www.thunderbolttours.com

Phone  0408 020468  (International :  61  2  408 020468)

Offline Macca

  • Elephant Trunk F2
  • *
  • Posts: 171
Hey guys,

Just stumbled across this post as well.  AWESOME stuff.  I've also read the official report and I believe there was a "double dry-line" set up in place which is not uncommon in situations such as this (in Australia).  I know of at least 2 other instances of such events (with Sept 29, 1996 being one of them).  Basically a trough (quasi-dryline) sets up to the east of the main trough...without thinking about it in any detail, i'm not sure what mechanism allows this to occur.  DP's on this day to the east of the quasi-dryline were in excess of 20C (I think I recall even as high as 22C), whereas to the west of the quasi-dryline the DP's were in the mid-teens (say 16C).  Then the main dryline further W sees the DP's drop to the low single figures W of this feature.  Also, the surface winds on the eastern side of the quasi-dryline are generally north to north easterly (maybe even easterly depending on the position of the surface low), whereas west of the quasi-dryline, the surface winds are more north westerly with westerly or even south westerly winds following the main dryline.  As you can see, this creates conditions which highly favourable for severe convection east of the quasi-dryline with greater turning in the lower levels and also much higher DP's allowing for greater instability. 

Storms can and often will develop on the main dryline as well but these are less likely to be supercellular/tornadic given the more linear shear, however, they can still pack quite a punch as the upper levels are usually more unstable further back to the west nearer to the upper level low/cold pool and the shear is still quite strong.

And just to make things interesting, in this case where there is such a strong upper level low/cold pool, you may even get storms "in" the cold pool as well given that surface temperatures would be quite tasty in January and there may be enough residual moisture left over from storms to kick off more. 

All bets are off when we get another set up like this.  BRING IT ON!

Macca

Offline wthrman

  • Rope Tornado F0
  • *
  • Posts: 8
  • Gender: Male
    • Kings Langley Weather

Wow, that is a nice set-up alright! Thanks for digging out those links above MB.

A couple of things caught my eye looking over those charts above. I would have thought the RH for 1000 and 850 would have been a little higher than around 50%. Is there any record of the LCL for that day? Probably not but thought I'd ask. Second thing is watching the surface low really develop between 00z and 06z. Quite awesome to see it take shape with increasing wind speeds around it as the upper cold pool approaches.



I just noticed this discussion and in particular James's post. I have reactivated the part of my website (www.wthrman.com) in which people are able to plot historical severe weather parameters back to January 1948. I had withdrawn it a couple of years or more ago, basically due to what I assumed was a lack of interest.

The plots are taken from the NOAA site but on my site you only have to click a few buttons to get dates etc instead of typing it all in on the NOAA version..unless of course you like all that sort of stuff!

Unfortunately there are no archived CAPE data that I am aware of, however you can plot lifted index, surface maps and thickness, and a whole range of wind and moisture profiles at different heights. You can refine it to a single state, and also see plots for other parts of the world including the USA.

The site also has soundings from 1973, too late for this event of course but that may be useful for other events.

I have just tested it quickly for 1/1/1970 and it works. Click on the Severe Weather plotting option on the main page.

I hope it's helpful.

Cheers...Keith
« Last Edit: 28 October 2007, 08:58:48 AM by wthrman »

Offline enak_12

  • Elephant Trunk F2
  • *
  • Posts: 153
  • Gender: Male

Offline Jimmy Deguara

  • Australian and Tornado Alley storm chaser
  • Administrator
  • Wedge tornado F5
  • *
  • Posts: 2,218
  • Gender: Male
  • Storm Chaser since 1993, Tornado Alley 2001
    • Australia Severe Weather
Enak,

You are lucky the Bureau even has it on the database  :)

Seriously, there was a report on the tornado from the Bureau but until the 1990's. Neverthless, the Bureau has not really rated tornadoes until the 1989 Elsmore, NSW tornado to my knowledge. Was the Brisbane tornado rated? Unless someone has seen the damage and done an appropriate survey, can you really rate a tornado?

Regards,

Jimmy Deguara
-------------------------------------
Australian Severe Weather
www.australiasevereweather.com

Australian Thunderbolt Tours
www.thunderbolttours.com

Phone  0408 020468  (International :  61  2  408 020468)

Offline Michael Thomas

  • Elephant Trunk F2
  • *
  • Posts: 172
  • Gender: Male
Enak,

I have wondered the exact same thing. Google searches send you straight to the wiki article or australian weather forums! Hardly the most reliable information out there (though still great for info). No hits in google scholar or web of science so it doesn't appear that any papers have been published regarding this event. Looking at the analysis charts posted I have little doubt that this day was a significant weather event for parts of eastern Australia. I am also inclined to believe there was a strong to violent tornado that day (otherwise everyone wouldn't be talking about this day would they?). I would like to see the BoM report, is it publicly available?

Besides a lot of trees and a tractor. it doesn't sound like it hit much. Throwing a two ton tractor 100 m is certainly impressive. Would that alone suggest that it was an F5? What was the extent of the tree damage? Just large branches snapped or were trees debarked?

I whole lot more questions than answers.

Offline enak_12

  • Elephant Trunk F2
  • *
  • Posts: 153
  • Gender: Male
Thanks Jimmy and Michael for your replys,

I wasn't aware when Australia was rating tornados, I assumed they may have estimated ratings on the older ones based on old reports and photos? 
I was thinking the same thing Michael about the two ton tractor sounds like they could get a pretty good estimate on the winds speed from that alone. Surely someone took photos of the forest damage and we would know if large trees were ripped from the ground say? Was the tractor report in the official review? I really wish it was online.

Don't get me wrong I do beleive there was a large and probably violent tornado this day, just hoping for more information :)

Offline Colin Maitland

  • Barrel tornado F4
  • *
  • Posts: 614
  • Gender: Male

"The Bulahdelah Tornado was an intense tornado which occurred near the town of Bulahdelah (100 kilometres (62.1 mi) north-northeast of Newcastle), New South Wales on 1 January 1970, and is thought to be the most destructive tornado ever documented in Australia.[1] It is thought to be least F4 or F5 on the Fujita scale however no official rating has been made public.[2][3]

 

How acurate do you beleive this information to be?

The synoptic charts posted above are impressive to say the least. How often would a setup like this or similar occur in Australia?



It is interesting that they state this, I thought the Bucca tornado rated F4 was the supposed to be the most powerful.

BoM states

The most intense tornado recorded in Australia - with a Fujita rating of F4 - occurred at Bucca, west of Bundaberg (Queensland), on 29 November 1992. The intensity of the winds created freak effects, such as embedding a picture frame in the wall of a room. Hail the size of cricket balls accompanied the storm.

So if the Bulahdelah Tornado 22 years earlier was supposed to be F4-F5 I would have thought along the lines that maybe BoM would have stated it to be equal or stronger than the 1992 Bucca tornado or vice versa. Its interesting. Would be good to have more info.  :)

Reference

http://www.bom.gov.au/climate/environ/tornadoes.shtml
http://en.wikipedia.org/wiki/1992_Queensland_storms
http://www.bsch.au.com/severewx/index.shtml



« Last Edit: 04 June 2011, 07:26:51 AM by Colin Maitland »

Offline Jimmy Deguara

  • Australian and Tornado Alley storm chaser
  • Administrator
  • Wedge tornado F5
  • *
  • Posts: 2,218
  • Gender: Male
  • Storm Chaser since 1993, Tornado Alley 2001
    • Australia Severe Weather
Listen,

With a path width of 1 mile you would almost guarantee it is a violent tornado. I have the report but there may be issues for it to be placed online. I will see if it is allowable. You can probably go to their NSW Bureau archives and ask for the report. I was also lucky to have the mapped path itself photocopied.

Regards,

Jimmy Deguara
-------------------------------------
Australian Severe Weather
www.australiasevereweather.com

Australian Thunderbolt Tours
www.thunderbolttours.com

Phone  0408 020468  (International :  61  2  408 020468)

Offline Michael Thomas

  • Elephant Trunk F2
  • *
  • Posts: 172
  • Gender: Male
Jimmy,

No doubt, if the tornado had a path width of 1 mile it must of been a very strong tornado. I suppose what Enak is getting at, all of the information on the internet is second hand.

Offline Colin Maitland

  • Barrel tornado F4
  • *
  • Posts: 614
  • Gender: Male
It would be without a doubt Australia's most destructive tornado to date that we know of. Just a pity that BoM does not use it as a guide to severity etc in rating tornadoes in Australia, but I suppose that is due to the fact of what Jimmy stated in a previous post " Seriously, there was a report on the tornado from the Bureau but until the 1990's. Neverthless, the Bureau has not really rated tornadoes until the 1989 Elsmore, NSW tornado to my knowledge."


(I am also curious to know if they have ever rated the Lennox Head tornado from last year, which is another subject.)

Just digging up some links to see what I could find. It is interesting that many sites have the Bulahdelah Tornado in its top 10 of the worlds most destructive tornadoes.


http://watchmojo.com/top-10/geography/
http://scienceray.com/earth-sciences/meteorology/10-most-destructive-tornadoes-from-around-the-world/3/
http://www.islandnet.com/~see/weather/storm/tornadoes-aunzea.htm

Colin