Deadly Auckland Tornado - May 3

[Dale]

Yes if you look at the shear profile in the sonde which went up just before the tornado struck, even I personally think there was not enough turning to outright itself be conducive to tonadogenesis.. it needed a little more oomph, something else.
Topographical influence is the only thing that comes into my mind which could be possible, I have seen localised effects very similar back over in Australia.

Which leads us to another point, bought up a page back in regards to high resolution doppler images.. we have had this discussion numerous times in the past and understand that not everything in life is free, but high risk days for areas affected, it would be nice to switch modes & release them to the general public at a reasonable refresh frequency.. at least for the duration of the warning period. More nowcasting? Thats a tricky one cause anyone can look at the weather and tell you what it is doing now, but to the uneducated trying to help, it could be a fatal combination.

Do feel sorry for that poor guy who was killed.. one of the workers for Fletcher Constructions at the Placemakers site.. he had no change being sucked off the roof and going on the ride of his life, which ultimately cost it. My heartfelt thoughts and condolences go out to his family, friends and co-workers on site.

The darker side of nature... who'da thunk it in downtown Auckland?

[RWood]

And M/S did a piss poor job on this one! and then go into nowcasting or beencasting.

Feel free to set yourself up as a tornado forecasting expert....

[Manukau heads obs]

movie of the high res rain rain radar
http://www.weather-display.com/download ... urnado.mp4

[Manukau heads obs]

you can see the very nice hook signature (look at the heaviest rain signal line)
note a opposite hook to northern hemisphere of course, but still strange to look at

I see that a weatherwatch reader reported sudden colder air ahead of the CB, and described it as forward flank downdraft, which is part of the engine room of the tornado (along with the rear flank downdraft)
this was a fully fledged mesocylone (on a small scale) !


lots of photos here:
http://www.nzherald.co.nz/nz/news/image ... 42#7581904

[NZstorm]

The tornado in the southern hemisphere is normally on the N or NW flank of the cb unlike USA tornadoes which are on the SW flank. Tornadic situations in NZ occur under low level NE flows with upper level flow NW. Tornadoes generally need strong wind fields to provide high enough helicity values, yesterday the winds looked a bit weak. But local terrain will have enhanced the flow locally. And as has been pointed out, a critical factor for the tornado is the very moist air with low LCL.

Landspouts are quite the opposite, they need weak winds and can develop in much drier air.

[Nev]

Here's an interesting Google Map showing the snaking path that the tornado took.

[Storm Struck]

Guys i had to have a wee snigger about this on Geoffs site, hes got the Tsunami photo up from Japan opps .
http://www.rambocam.com/

Yesterdays tornado was captured well, i think with the combination of technology most people have camera's on thier phones etc and the fact it struck a populated area gave everyone a chance at getting the tornado.
Also the Duration of the tornado as it traveled, is there any estimates as to how long the path of the tornado was?

[Manukau heads obs]

is there any estimates as to how long the path of the tornado was?

yes, that was already mentioned in this thread, around 15km

[03Stormchaser]

Auckland climate scientist Jim Salinger and WeatherWatch analyst Philip Duncan estimated from video images of the tornado and the damage it left that it would have been twisting at 200km/h or more.

That put it at a force of 2 on zero-to-5-point scale

http://www.nzherald.co.nz/nz/news/artic ... d=10723260

So EF2 (F2 as I think we still use the Fujita scale in NZ) is what they have given it, any word from metservice?

Considerable damage.
Roofs torn off frame houses; mobile homes demolished; boxcars overturned; large trees snapped or uprooted; highrise windows broken and blown in; light-object missiles generated

I would say its did reach F2 but for most of its 15km journey it was only a F1.

Even though ive posted quite a few videos here, but found this on this evening:
http://www.youtube.com/watch?v=-U9cht_kNzc

[spwill]

Yesterdays tornado was captured well?

Yes, a lot of good footage.

[metpete]

http://blog.metservice.com/2011/05/alba ... -may-2011/

[tgsnoopy]

And M/S did a piss poor job on this one! and then go into nowcasting or beencasting.

Feel free to set yourself up as a tornado forecasting expert....

Speaking of which, I haven't seen the tornado whisperer in here for a while.

[NZstorm]

I would say its did reach F2 but for most of its 15km journey it was only a F1.

I haven't had a chance to look at the tornado damage as work has kept me busy. yes, looks like a solid F1. It could just make it to an F2 based on the way some of the vehicles where tossed over at the Albany shopping centre.

[03Stormchaser]

http://blog.metservice.com/2011/05/alba ... -may-2011/

Thanks for the link, no mention of any rating though.

[Manukau heads obs]

nice and detailed write up from the M/S there, very interesting ,thanks

[Manukau heads obs]

I do see a typo in that M/S article Peter:

Radial velocity, 2.54pm Tuesday 2 May 2011. Warm colours (yellow through to red) denote wind speeds away from the radar; cool colours (green through to blue) denote wind speeds away from the radar.

one should be away, the other towards....not both away

[Tornado Tim]

Thanks Peter Kreft!

Especially for attaching a doppler wind image

It does prove there was a bit of a meso even though it was smaller in scale in comparison to U.S meso's (but in all honesty you cant compare the two).

Since the radars in NZ are doppler have you tried looking at the Level 2 data from the radar to see where the rotation was mostly confined to? eg: which bit of the hook contained the most rotation.
Since the radar images that I have seen are Composite Reflectivity's (all levels combined in one) it would be good to see the individual layers.

Thanks for the Write up again Peter

[Nev]

Yes, thanks for posting that report Peter.

This excerpt is from news.com.au (not sure if its accurate)...

'Violent tornado rips through northern Auckland, killing one person and leaving 10 in hospital'
May 04, 2011 2:30AM

...MetService weather specialists have confirmed the tornado was categorised an EF2 on a scale between EF0 and EF5. While far smaller than tornadoes to hit the US, it was still the largest twister New Zealand had seen in several years, the centre reported. Its weather ambassador Bob McDavitt said the tornado was a rare event caused by an unusual storm system over Auckland.

There were also reports of cars at the Albany Megacentre not just tossed, but sent skyward, with one car reported to have been lifted 20-30 metres into the air.

Based on some of the initial footage, Jim Salinger (who apparently is also somewhat of an expert on tornadoes) has been indirectly quoted as saying that he estimated it would have been an EF2. And according to tornado expert Geoff Austin of Akld Uni's Geophysics dept, interviewed on Close-Up last night, that would make it one of only 4 or 5 NZ tornadoes to reach at least F2 in the last 100 years.

[Michael]

There was a kind of a front over auckland then or boundary than a front and winds seemed to be easterly some place and northerly elsewhere or NE so maybe switching locally as below.

Tornadic situations in NZ occur under low level NE flows with upper level flow NW. Tornadoes generally need strong wind fields to provide high enough helicity values, yesterday the winds looked a bit weak. But local terrain will have enhanced the flow locally. And as has been pointed out, a critical factor for the tornado is the very moist air with low LCL.

[03Stormchaser]

And according to tornado expert Geoff Austin of Akld Uni's Geophysics dept, interviewed on Close-Up last night, that would make it one of only 4 or 5 NZ tornadoes to reach at least F2 in the last 100 years.

I think that number will be alot higher ( or 5 NZ tornadoes to reach at least F2 in the last 100 years) How many would open areas that it is hard to judge the strength? The Methven tornado on the 14 dec 2009 I would have thought would have been a F2 but I never heard anything about it from metservice etc about a rating.

If someone knows but do Metservice have a team who go out and check reports of damage from tornadoes?

[BeaconHill]

This satellite image via MODIS seems to have been taken maybe soon after the event??
http://rapidfire.sci.gsfc.nasa.gov/subs ... .aqua.250m

Is the lump at the bottom of the "hook" of cloud over the Auckland region the offender making off towards the Wiakato? I'm not sure how to tell the exact timeing of that image.

Linked from here: http://rapidfire.sci.gsfc.nasa.gov/subs ... nd.2011123

[Thunder]

Speaking of which, I haven't seen the tornado whisperer in here for a while.

Still very much here tg, and have been following this event with great interest. I've always continued to have an interest in thunderstorms and I still look at the weather forum alot but haven't posted as much in the last we while. I'm not exactly sure of the cause, 4 years of forecasting might've sucked a bit of the passion out've it for me but I haven't been doing that for a while now and this event has surely sparked me to life a bit so hopefully a resurgence coming.

The amount of footage on youtube! Have downloaded a fair bit. Hopefully I can forecast another tornado in the future, just gotta do a few other things first.

Cheers
Aaron

[tgsnoopy]

Hopefully I can forecast another tornado in the future, just gotta do a few other things first.

Well I sure hope you can again, cause I was the one who benefited from your accurate predict... err forecast

[Nev]

...And according to tornado expert Geoff Austin of Akld Uni's Geophysics dept, interviewed on Close-Up last night, that would make it one of only 4 or 5 NZ tornadoes to reach at least F2 in the last 100 years.

Oops, it was actually Bob McDavitt that made that comment on Tuesday night's Close-Up interviews.

I think that number will be alot higher...

Yes, I agree.

[Manukau heads obs]

There were also reports of cars at the Albany Megacentre not just tossed, but sent skyward, with one car reported to have been lifted 20-30 metres into the air.

there is a photo on weatherwatch.co.nz that I saw that captured a yellow car in the air