South-Hamilton Tornado F-1 damage photos

meeekael · Unread post by **meeekael** » Sat 17/09/2005 20:18

I was out there when willo (foggy) was taking photos. I am by no means a weather expert or anything, but from what I saw, almost all the trees were blown the same way. This was also illustrated at the scout hall where the cryptomeria hedging in the centre of a padock had been blown and had fallen to bits, one side of the fence was completely clean of debris, while the other side (the direction of the wind) was covered in it, this was pretty much in the direct path of the "tornado" yet if there was a tornado, wouldn't debris be everywhere? Its also points towards more of a squalthing with the shots that willo took of the large bands of shrubery in the gardens, all of it is blown the same way.

but like I said, I am merely bring up points, I have no clue about anything weather related.

Manukau heads obs · Sat 17/09/2005 20:36

on the news, a person interviewed, described how the air pressure suddenly dropped like a vacuum..
a fast moving weak tornado will have stronger winds on one side, becuase of the forward speed you have to add to the speed of rotation, and so one side would have alot more damage than the other
but, yes, you should see trees that look like they have been twisted out of the ground, or lifted up and then put down again, instead of just simply blown over
hummmmmm !

NZstorm · Unread post by **NZstorm** » Sat 17/09/2005 20:52

I think it was a micro-burst but am not completely ruling out a tornado. Damage photos and last nights weather environment suggest a microburst.

Willoughby · Unread post by **Willoughby** » Sat 17/09/2005 23:18

NZstorm wrote:I think it was a micro-burst but am not completely ruling out a tornado. Damage photos and last nights weather environment suggest a microburst.

It was a microburst up to about the cemetery, big updrafts came about from wind rising rapidly due to steep terrain at the gardens and cemetery.
I then believe it turned into an F-1 at Cobham "Hill Summit" and went down hill from then on SH1. Reports say it was a tornado around the lower Hillcrest area. The house with the most roof/tilings off, (20%) all had it bad in all directions. (Between Cobham Summit and Caltex)

Here's one corner of the house facing south

Would those kind of updrafts and possible down winds from the squall line I mentioned create a tornado? The topography here is very steep near the cemetery and SH1. Steven W? Aaron Wilkinson? others?

Manukau heads obs · Sun 18/09/2005 03:14

fom my unerstanding, thats all the ingredients for a tornado, yes,

NZstorm · Unread post by **NZstorm** » Sun 18/09/2005 08:53

A microburst and a tornado are formed by entirely different processes.
A microburst is caused by outflow from the thunderstorm. A tornado is formed by inflow into the thunderstorm. So you couldn't get a microburst suddenly changing into a tornado. I would not expect a tornado in the immediate vicinty of a microburst. But there is such a thing as a gustnado which has nothing to do with a tornado. It is outflow(microburst) that develops spin when it hits the ground.

Gary Roberts · Unread post by **Gary Roberts** » Sun 18/09/2005 08:55

NZstorm wrote:A microburst and a tornado are formed by entirely different processes.
A microburst is caused by outflow from the thunderstorm. A tornado is formed by inflow into the thunderstorm. So you couldn't get a microburst suddenly changing into a tornado. I would not expect a tornado in the immediate vicinty of a microburst. But there is such a thing as a gustnado which has nothing to do with a tornado. It is outflow(microburst) that develops spin when it hits the ground.

Once a tornado has formed what sustains it, and how long do they usually last? Do larger ones hang around longer than smaller whirlwinds?

Manukau heads obs · Sun 18/09/2005 08:57

you learn something new every day

Mooloo · Unread post by **Mooloo** » Sun 18/09/2005 11:31

Hi all, im a new user on these forums, and another hamiltonian! Are you and I the only people from Hamiltron Foggy? Nice photo's by the way. The Tornado missed my house by about 300 meters. I think its safe to say it was a "mini tornado" rather than a squall as the damage is very localised and there seems to be a sort of 50 meter wide corridor of damage. I went out to Matangi to watch the rugby at a friends house last night and the damage blew me away. It was incredible.

There is another bonus as well....I managed to nab about half a tralor load of firewood from beside the road!!

PS. Willow its Sam from geo

Gary Roberts · Unread post by **Gary Roberts** » Sun 18/09/2005 11:35

Mooloo wrote:Hi all, im a new user on these forums, and another hamiltonian! Are you and I the only people from Hamiltron Foggy? Nice photo's by the way. The Tornado missed my house by about 300 meters. I think its safe to say it was a "mini tornado" rather than a squall as the damage is very localised and there seems to be a sort of 50 meter wide corridor of damage. I went out to Matangi to watch the rugby at a friends house last night and the damage blew me away. It was incredible.

There is another bonus as well....I managed to nab about half a tralor load of firewood from beside the road!!

PS. Willow its Sam from geo

Foggy reckoned it missed his place by only 100-300m, so you guys must be neighbors!

Mooloo · Unread post by **Mooloo** » Sun 18/09/2005 12:31

Haha yea we just about are! We know eachother. He sent me a txt message last night to come check out his photo's so i thought i'd sign up and start foruming too

Mooloo · Unread post by **Mooloo** » Sun 18/09/2005 14:00

I just had a bit of spare time so went out to get a few photos of the damage. They are no where near as dramatic as foggy's as it this is 2 days after the event however they can give u an insight into the scale of the damage...

NZstorm · Unread post by **NZstorm** » Sun 18/09/2005 17:17

I think its safe to say it was a "mini tornado"

Hi Mooloo. I did a survey myself of the damage path today, about 3km of it. I have changed my thinking, and now think it most likely was a tornado. Got some pictures for my website.

03Stormchaser · Unread post by **03Stormchaser** » Sun 18/09/2005 17:24

NZstorm wrote:
I think its safe to say it was a "mini tornado"
Hi Mooloo. I did a survey myself of the damage path today, about 3km of it. I have changed my thinking, and now think it most likely was a tornado. Got some pictures for my website.

Reason for change NZstorm?

I think it wasnt a tornado rather a Landspout, why? because it isnt associated with a wall cloud or mesocyclone. In my opinion a tornado can only be formed by storm-scale rotation. Which i think wasn't evident here.

TonyT · Unread post by **TonyT** » Sun 18/09/2005 17:56

Interesting discussion, and nice to have some different ideas to consider. Further to the gustnado theory, in complex terrain such as this it would certainly be possible for a microbusrt type wind to develop a very brief (ie a few seconds rather than few minutes) of rotation due to interaction with the topography. There wouldnt need to be any special meteorological factors to achieve this, and it would just be a random chance based on the direction and speed of the wind from the microburst and the location and shape of a nearby slope or hill. That could explain why it cant be easily categorised as either a tornado or microburst. Just a thought.

NZstorm · Unread post by **NZstorm** » Sun 18/09/2005 18:01

I think it wasnt a tornado rather a Landspout, why? because it isnt associated with a wall cloud or mesocyclone. In my opinion a tornado can only be formed by storm-scale rotation. Which i think wasn't evident here.

I think a mesocyclone was possible stormchaser, based on the relatively high helicity values we have been getting in the north here over the last few days. And I am sure there was a front crossing Waikato Friday night which would beefed up the dynamics.

Gary Roberts · Unread post by **Gary Roberts** » Sun 18/09/2005 18:09

NZstorm wrote:
I think it wasnt a tornado rather a Landspout, why? because it isnt associated with a wall cloud or mesocyclone. In my opinion a tornado can only be formed by storm-scale rotation. Which i think wasn't evident here.
I think a mesocyclone was possible stormchaser, based on the relatively high helicity values we have been getting in the north here over the last few days. And I am sure there was a front crossing Waikato Friday night which would beefed up the dynamics.

Okay, now you guys are just pulling our legs, right? This is starting to sound like an engineroom discussion from Star Trek: Voyager.

Willoughby · Unread post by **Willoughby** » Sun 18/09/2005 19:50

Mooloo wrote:Are you and I the only people from Hamiltron Foggy?

Yes indeed, quite a lot of Cantabs and Jafas dominating the forum though

Great to see you have posted some pics!

Gary Roberts wrote:Okay, now you guys are just pulling our legs, right? This is starting to sound like an engineroom discussion from Star Trek: Voyager

Very interesting to learn, from something so close and rare!

Steven, you came down here today to have a look? That's dedication!

You have to see it to believe it I guess TonyT, they saw spirialing things!
I'm not 100% sure though it was a tornado

Willoughby · Unread post by **Willoughby** » Sun 18/09/2005 20:09

The Glenview WS (West side of the river adjacent to Hamilton East) reported some 11.5mm in 5 minutes.

We had hail, it sounded extremely loud on the roofs, but lasted just 15 seconds and the extremely heavy precip washed it away. Roughly 1cm in diameter, very shortlived.

The station also reported a slight rise in pressure of 1mb

NZstorm · Unread post by **NZstorm** » Sun 18/09/2005 20:13

Steven, you came down here today to have a look? That's dedication!

Its not often you get to see a good trail of damage from a thunderstorm.

I was hoping to see another thunderstorm in the Waikato today but it was just overcast wet weather.

Thunder · Unread post by **Thunder** » Sun 18/09/2005 20:13

When me and foggy were chatting that night looking at skew-t's there was a nice big jet stream over the area. The atmosphere looks like it could well of supported a tornado indeed. Look foward to the photo's Steven!!! Dam the site looks good, argghh ...........I am procrastinator extrodinair!!

Cheers

Mooloo · Unread post by **Mooloo** » Sun 18/09/2005 20:58

Dedication! Where abouts did u go to visit the damage? Whats the situation like at the hamilton Gardens foggy? Have they fixed up most of the debris? The gardens administration must be pretty pissed off, its gonna take a long time before it looks perfect again!

Willoughby · Unread post by **Willoughby** » Sun 18/09/2005 21:21

Mooloo wrote:Dedication! Where abouts did u go to visit the damage? Whats the situation like at the hamilton Gardens foggy? Have they fixed up most of the debris? The gardens administration must be pretty pissed off, its gonna take a long time before it looks perfect again!

They have fixed the glasshouse I believe as this poses a very serious hazard risk.. Most of the trees are still there as today was not a good day to spend hours cutting trees! (56mm today so far)

Mooloo · Unread post by **Mooloo** » Mon 19/09/2005 10:56

Yes i drove past the gardens today, the workers were just begining to clear away all the branches etc. prety crazy!

NZstorm · Unread post by **NZstorm** » Mon 19/09/2005 12:05

Where abouts did u go to visit the damage?

I followed the damage trail from near the hospital to the houses in Hillcrest that had the tarpaulins on the roof. A distance of about 3km.
There is enough tree damage there to keep the parks people busy for a for a while.