NZ Weather Forum

Manukau heads obs wrote:good idea
because once you have downburst tinted glasses on, its hard to be be pursuaded otherwise...

Mind you some may think I have tornado tinted glasses on...

same could be said about me

My thinking is that we all agree it was wind-damage associated with a cloud-- a Cb.

As to whether the the cause was within the updraft (as a tornado) or on the updraft/downdraft interface (as a surface eddy or terrain enhanced whirlwind), or within the downdraft (as a down burst) seems to be to be a exercise of academic extravagance for the pendant and purist, unless it is being conducted by an Insurance agent attempting to find a loophole to prevent a payout.

The squall line responsible arrived in Fiji on Tonga on Thursday night . It reached them as fast as an express train, with NW winds rising to 30 gut 40 knots during half an hour, then spinning to a southerly 35 gusting 50 to 60 knots within five minutes that lasted for around half an hour and then followed by a long lull and a few lesser squalls. No reports of Tornadoes in Fiji and Tonga but plenty of "gust damage'.

bobbymcd wrote:My thinking is that we all agree it was wind-damage associated with a cloud-- a Cb.

As to whether the the cause was within the updraft (as a tornado) or on the updraft/downdraft interface (as a surface eddy or terrain enhanced whirlwind), or within the downdraft (as a down burst) seems to be to be a exercise of academic extravagance for the pendant and purist, unless it is being conducted by an Insurance agent attempting to find a loophole to prevent a payout.

The squall line responsible arrived in Fiji on Tonga on Thursday night . It reached them as fast as an express train, with NW winds rising to 30 gut 40 knots during half an hour, then spinning to a southerly 35 gusting 50 to 60 knots within five minutes that lasted for around half an hour and then followed by a long lull and a few lesser squalls. No reports of Tornadoes in Fiji and Tonga but plenty of "gust damage'.

Hello Bob McD!
A big Welcome to the NZ Weather Forum!

yes, welcome along Bob

or on the updraft/downdraft interface (as a surface eddy or terrain enhanced whirlwind), or within the downdraft (as a down burst)

yes, I can see that sort of thing occuring....and does...but to my thinking that is normaly short lived...not 2km long path..and also not such a narrow and straight line path either

Wow we have weather royalty among us,welcome Bob

Welcome Bob

Hi all,
yep I'm willing to occasionally add my ideas to the forum- all in the pursuit of the fun of sharing enthusiasm for 'the elements'.

bob

Hi Bob.

As to whether the the cause was within the updraft

Typically a landspout

or on the updraft/downdraft interface

A tornado.

within the downdraft

Squalls can produce gustnadoes.

The house that lost its roof had been refurbished in 2008, which points to F1 strength winds in that spot. A person who lives in that street reckons he saw a tornado come in and it was bouncing with debris spinning up. He was sure it was a tornado and not a squall.

the issue I have with a gustnado is they would tend to cause damage over a wider path I would have thought
or at least more of a lessening trend of damage away from the center of the worst damage, either side
sort of thing

rather than a narrow (only) path of damage which occured
(most noticeable in Ben's video of the tree/fence damage)

My mate also saw it on the golf course, he saw it spinning,. I'm convinced it was a small tornado from the damage I saw. i just happend to bump into the scene about ten mins after, while heading to my dads for tea and before much stuff had been moved around. Welcome bob we are all weather purists here

ben g wrote:My mate also saw it on the golf course, he saw it spinning,. I'm convinced it was a small tornado from the damage I saw. i just happend to bump into the scene about ten mins after, while heading to my dads for tea and before much stuff had been moved around. Welcome bob we are all weather purists here

Hi Ben G. Really nice photos. What's your best estimate of the time this event occured?

Weather Watcher wrote:

ben g wrote: Hi Ben G. Really nice photos. What's your best estimate of the time this event occured?

Hi Weather Watcher, do Metservice ever do damage surveys in such events ?

We have done a few in the past, but not as many as I think we should. The Waikanae microburst in July 2011 was one that was that was investigated. I believe NIWA have done some of the Taranaki tornadoes.

Hi
Did Ben ever get to you the timing of the event?

Manukau heads obs wrote:Hi
Did Ben ever get to you the timing of the event?

Not yet. I'd like to know the time so I can compare it with the correct radar imagery.

Sorry no, not exactly sure of the time, we did have a power flicker that I assume was the Tin hitting the lines but I did not take note at the time and it is becoming murky in memory now. Around 6.15-630.
Interesting pic from the paper, the other half of the missing roof. How far it flew with out hitting anything Sorry for the late reply I have a bad habit of not checking in when the big highs move in.

Appreciate the great reports and images Ben.

Most media reports say the event occurred either, just after 6pm, 6:15pm or 6:20pm.

Interesting that the power-cut to about 600 homes was reported to have been caused by a Chorus telephone pole being 'knocked' onto power lines on the corner of Tainui and Vauxhall Rds (in front of the shops). That looks to be over 60m NE of the house that lost its roof in Sinclair St.

The pole that came down was on the corner of Sinclair st and vauxhall. I suspect the tin on the main lines may have had a bit to do with the power cuts. I will find those pics and explain them better

Thanks for the times.

Thanks Ben. Sounds like the initial pole location report must've been an error.

Great reports by ben g for this storm event.

Edit

Right place at right time!
Here's the offending power pole snapped off at base, but it looks like wires in the conduit going to the ground have put a stop to its travels, photo taken from about half way between Albert rd and Sinclair st, the fire engine is parked in Albert rd
Looking south Looking southeast Looking south east, from corner sinclair st and vauxhall. the tin on the lines has ended up well to the left hand side of the narrow debris line

Fire dispatch times narrow it down a bit,