South Island Storms 20/11/19

[Awhituobs]

razor did post a screen shot of it...see further up this thread

[Nev]

My mistake yesterday was not to get a photo as soon as we saw the funnel, instead I thought we would get closer before getting a shot and by then it had largely shrunk. Is anyone able to get a screen shot of the radar? surely it would have shown up on it.

What time was this?

[Richard]

Around 4.30 -edit- closer to 4.45

[Nev]

Zoomed 4:30pm 120km image…

MetService Chch Radar - Nov 20, 4.30pm.png

[Richard]

That makes sense,Waikari is marked

MetService Chch Radar - Nov 20, 4.30pm.png

[Richard]

And this was where we first parked while the clouds were rapidly rotating

MetService Chch Radar - Nov 20, 4.30pm.png

[Razor]

My mistake yesterday was not to get a photo as soon as we saw the funnel, instead I thought we would get closer before getting a shot and by then it had largely shrunk. Is anyone able to get a screen shot of the radar? surely it would have shown up on it.

Here's another photo, still zoomed in which makes them look closer than they are

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I also posted this yesterday, couple of pages back in this thread, fits your timescales? 4:40pm approx

Annotation 2019-11-20 164517.jpg

[NZstorm]

That makes sense,Waikari is marked MetService Chch Radar - Nov 20, 4.30pm.png

My thoughts are that it is just a random precip pattern but could also be linked to an upper level vorticity lobe. I think the funnels would be very small scale circulations and not easily recognisable on the radar.

[NZstorm]

Great photos/videos! Why is it that several posters here were able to recognise yesterday there was a chance for severe hail, but Metservice did not mention this until quite late (when it was already happening in Timaru, wasn't it?)

The climatology is there for severe hail events in Canterbury in November. Severe weather forecasting is about assessing risk so yes, they should have mentioned the risk.

You don't have to have wind shear to get golf balls but it does increase the odds, especially when you have the cold air aloft. The bulk shear yesterday was 40 knots, a favorable number.

[mikestormchaser]

Great photos/videos! Why is it that several posters here were able to recognise yesterday there was a chance for severe hail, but Metservice did not mention this until quite late (when it was already happening in Timaru, wasn't it?)

The climatology is there for severe hail events in Canterbury in November. Severe weather forecasting is about assessing risk so yes, they should have mentioned the risk.

You don't have to have wind shear to get golf balls but it does increase the odds, especially when you have the cold air aloft. The bulk shear yesterday was 40 knots, a favorable number.

Nzstorm is dec, jan, feb still good months or are you saying November is best? As we have had some good supercells in dec and even feb.. probably a silly question

[Razor]

Nzstorm is dec, jan, feb still good months or are you saying November is best? As we have had some good supercells in dec and even feb.. probably a silly question

Don't forget this one too...

https://www.reddit.com/r/newzealand/com ... istchurch/

[NZstorm]

Nzstorm is dec, jan, feb still good months or are you saying November is best? As we have had some good supercells in dec and even feb.. probably a silly question

Yes, I was meaning November is part of the severe hail season.

[mikestormchaser]

Nzstorm is dec, jan, feb still good months or are you saying November is best? As we have had some good supercells in dec and even feb.. probably a silly question

Don't forget this one too...

https://www.reddit.com/r/newzealand/com ... istchurch/

Yeah that was a very early surprise! Aaron and i got that one good!! Captured heaps of video from that storm!! The report is up on stormchasers.co.nz website of that day

[Dean.]

Still hail on the ground 24 hours later...one of the most potent storms in a long time

20191121_132121.jpg

[Nev]

Around 4.30 -edit- closer to 4.45

I've put together a sequence of images of that cell around those times…

MetService Chch Radar - Nov 20, 4.00pm-4.52pm.png

[David]

Video from Timaru

https://www.reddit.com/user/steamdriven ... over_water

[Richard]

That makes sense,Waikari is marked MetService Chch Radar - Nov 20, 4.30pm.png

My thoughts are that it is just a random precip pattern but could also be linked to an upper level vorticity lobe. I think the funnels would be very small scale circulations and not easily recognisable on the radar.

yes, and thinking about that vortex more it wasn't over as far away as Waikari, 5-10 km north where Waikari was about 15km.

[TonyT]

My thoughts are that it is just a random precip pattern but could also be linked to an upper level vorticity lobe. I think the funnels would be very small scale circulations and not easily recognisable on the radar.

yes, and thinking about that vortex more it wasn't over as far away as Waikari, 5-10 km north where Waikari was about 15km.

Radar can't see what's happening near the ground that far from the radar antenna - the earth's surface curves so the further away you are from the radar site the higher in the atmosphere the lowest layer of the radar beam can see. So by the time you get as far as Waikari the Rakaia radar is probably looking at what happening 1km above ground level. Therefore it would probably not "see" the low level funnel you could see, but it may be able to detect the pattern above, which may not be directly over the surface feature.

[grinch]

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This happened at my place (near Cust) on Wednesday at approximately 3pm. There was a noise like a jumbo jet, followed by a gust which was more like a blast from an explosion than a gust of wind. This gust felled more than thirty mature trees on our property simultaneously and was accompanied by golf ball sized hail. A couple of the trees, which the logging contractor estimates to weigh around 6 tonnes, were uprooted and tossed five metres out into the paddock. A mature pine tree was uprooted and fell on my neighbours house and, like us, they have also had serious damage to trees and vehicles. All the trees have fallen in the same direction and the trail of destruction follows a path maybe 200 metres wide with clearly defined edges outside of which there is no damage whatsoever. It travelled for at least a kilometre, although I suspect much further, but I am unable to follow the path as it went out across farmland and riverbed. My question is, what the hell was it?! Tornado? Or something else? Whatever it was it has cost us an awful lot of money in a very short space of time!

[Richard]

That is a real mess you have to deal with there, wonder if it was a tornado?

[Rogue]

Without radar velocity scans or visual confirmation, it is hard to conclude whether or not it was a tornado, as opposed to localized straight line winds. However there has been plenty of reports of damage along a path over north Canterbury. Are you able to give an address or approximate location? Would be interesting to see how all of these reports align.

Here is a message I exchanged with a lady from North Loburn on Facebook:

"We must have got home just as it came through. Had a big pine branch down across driveway and then this mess. We had a wooden dog box moved about 50 mtrs and smashed to pieces and a dog trailer weighing around 300kg moved about 30 mtrs. Also had a wooden climbing wall of a kids fort thrown over the neighbours deer fence. Our neighbour on that side was at the front side of the house as she said there was just stuff flying everywhere out the back ( our side). Weird thing is right next to the shed we have a massive burn pile with all sorts on it and not 1 thing moved?

Someone lost their roof but that was more over okuku area and also a few people saying they saw one over there with lots of trees down etc. Was super crazy. We even had a plastic toboggan next to the shed and it hadn't moved."

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bee

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[grinch]

We are at the Cust end of German Road and the trajectory that this thing took would certainly have taken it across the Ashley River towards Okuku and North Loburn. I believe it started directly across the road from us as there is no sign of damage any further back.

[NZstorm]

Thanks for the damage reports grinch and Rogue, very interesting. If the wind came with the hail it may have been a microburst. You can get large amounts of negative buoyancy in some storm clouds and the descending air can gain a lot of velocity before it reaches the ground.

[Thunder081]

Here's all the radar images

Single images download here: http://www.mediafire.com/file/o1nw67xm3 ... 9.zip/file

[Nev]

^ Thanks Thunder081. Note that your timestamps are in NZST rather than NZDT.