Widespread Storms, South Island 23/2/14

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NZstorm
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Re: Widespread Storms, South Island 23/2/14

Unread post by NZstorm »

Copy of the Christchurch sounding for 4pm off the gfs. The gfs was under forecasting the NE wind/available moisture so I made an adjustment for dp/CAPE.

The lapse rates from the surface to 700mb were almost almost dry adiabatic (10C).
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Re: Widespread Storms, South Island 23/2/14

Unread post by TonyT »

1625724_10152029099514790_776132239_n.jpg
A few more thoughts:

A friend of mine posted this photo on Facebook, taken at Waikuku. This ties in with my estimate that where I first saw the finger cloud from my location on Amberley beach was west of the Waikuku area. It also implies the tornado (if it was the same one) was in existence for at least 15 mins (about the time it would have taken from when I first saw it to when it was gone), and took a path from west of Waikuku, across the Ashley River, towards AMberley, it would have been running roughly parallel with SH1, just ion the inland side. For most of this time I didnt see a classic funnel cloud shape, only the dark grey blob, but once it got to about the Liethfield area the more typical funnel appeared (which is when the video posted above was being filmed).

Another friend in Amberley reports dents from hail in the roof of his car and caravan.

The video on the NZ Herald site shows the mess made of Elliotts plant nurseries, which explains the plastic I saw being lifted high into the vortex. A piece of this has come down somewhere near us (about 3km away from source).

One of the things I recall very vividly from when the tornado was closest to me (about 2km away from the damage path) is the winds in the clouds. I was facing the vortex and seeing clouds shooting almost directly towards me, yet at the same time I had clouds running fast from my right shoulder up and over me (ie directly opposing the outflow from the tornado), and also from my left shoulder at 90 deg to both these other winds. Never seen anything like it before. Wind was a good solid E to NE about 30 mins before the event, like a typical summer NEle, a good 15 knots. As the wall cloud approached it became dead calm. Then the wind picked up over abour 3-4 mins from the S-SE. Then as the tornado was closest we got about 90 secs of E-SE winds around 30 knots gusting 40 or so. Thats when the hail started.
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Re: Widespread Storms, South Island 23/2/14

Unread post by Manukau heads obs »

re the cloud circulation..sounds like a mesocylone circulation..some of the photos I have seen shows that...but not completly circular...more like in a snake curve..which you can still get with a not complete meso
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Re: Widespread Storms, South Island 23/2/14

Unread post by Skywatcher »

I'd forgotten I took some video looking south when the lightning trigger wasn't picking anything up just after 16.50. A couple of flashes, one with distant strobing CG and I also speeded up the video to show cloud motion.
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Re: Widespread Storms, South Island 23/2/14

Unread post by Nev »

Thought this MS track-map of yesterday's tornado spawning supercell might be of interest…
MetService wrote: Here is the track of yesterday's supercell based on the radar imagery. The system formed around 2pm off the coast of Canterbury before moving northward and dying away around 6:45pm near Motunau Beach. ^JL
MetService - Feb 23 Canterbury Supercell Track-Map.png
Source: MetService - facebook
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Re: Widespread Storms, South Island 23/2/14

Unread post by Richard »

Neat how that small storm west of CHCH moved SE and joined the main sysem
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Re: Widespread Storms, South Island 23/2/14

Unread post by mikestormchaser »

Interesting map there nev, good stuff. here is a photo i shot of the in coming supercell, to the right is the mesocylcone, and underneath that appears to be a lowering, (wall cloud) with a very small nipple popping out.
This is where i think steve saw the first tornado.. not sure if it was still on the ground at this point.
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Re: Widespread Storms, South Island 23/2/14

Unread post by Nev »

Cheers Mike. Here's couple more rather moving videos; the first as the tornado nears the family's home, and the second just after it passes…


Tornado in Amberley [1], by Kurstie Griffin


Tornado in Amberley [2], by Kurstie Griffin
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Re: Widespread Storms, South Island 23/2/14

Unread post by Manukau heads obs »

great vidoes !
the clothes line spinning is like..tornado allright, LOL
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Re: Widespread Storms, South Island 23/2/14

Unread post by Orion »

Thanks for putting those videos here, Nev.
Must have been a frightening experience for the family in the thick of it.
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Re: Widespread Storms, South Island 23/2/14

Unread post by Storm Struck »

Interesting to note the very strong winds in the second video almost as if the southerly was being sucked inbehind the tornado, I did notice that even though a southerly went through with the storm it only lasted 5-10 minutes before swinging back lighter NE even during the storm while driving back into the city from Leeston.
The southerly came up again later on around 7pm.
There is something with this area too for Waipara/Amberley, as there have been tornado's in the past within the area.
I am thinking the general topography creates a bowl affect with the eastern low lying hills just north of Amberley township blocking out the onshore NE flow and creating a funnelling affect.
Much like what happens in the Tai Tapu, Leeston and Lincoln areas where many tornado's have touched down in the past and as Steve spotted on Sunday too.
So in the future if storms shift north or fire more so over mid to north Canterbury it might pay to keep an eye on the area.
I know there have been previous tornado events in the area does anyone have links to this?
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Re: Widespread Storms, South Island 23/2/14

Unread post by Richard »

Yes Jason,there has been three tornado that i remember in that area,one in the mid 90's that crossed Lawcocks Rd and then there was a storm 1991 or 92 where again near Lawcocks road there was trees blown facing west while 2kms to the north trees lay facing east,dont know if that would be called a tornado but that was certainly a massive rotating storm
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Re: Widespread Storms, South Island 23/2/14

Unread post by mikestormchaser »

Currently reading up on the difference between HP and LP supercells, seems we would be extremly rare to get an HP supercell here in new zealand unless the moisture levels are extremly high for one factor.. Would be nice to have one though as the potential for tornadoes would be greater again, however more dangrous being rain wrapped :wave:
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Re: Widespread Storms, South Island 23/2/14

Unread post by NZstorm »

There was a tornado at Amberly 19 December 1993.

The other type of storm to look at is 'classic supercell' Mike.
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Re: Widespread Storms, South Island 23/2/14

Unread post by mikestormchaser »

NZstorm wrote:There was a tornado at Amberly 19 December 1993.

The other type of storm to look at is 'classic supercell' Mike.
Indeed nzstorm :) thanks for pointing that out :) seems its rare to get a classic text book supercell or HP in new zealand? or is it possible under the right conditions?
Also this friday another chance it seems for thunderstorms/hail
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Re: Widespread Storms, South Island 23/2/14

Unread post by 03Stormchaser »

1599734_10201864487988751_1748441249_o.jpg
Fantastic shot here from David Hardy on Facebook.

Rating for this tornado, from most of the damage I saw only F0 with occasion F1. Most damage to dwellings was on Double Corner Rd. I visited a couple of houses there to see if they were alright (the first person to visit them even though it was about 10min after the tornado) and the damage was very minor to the dwellings, mostly from trees and branches damaging them.
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Re: Widespread Storms, South Island 23/2/14

Unread post by NZstorm »

mikestormchaser wrote:seems its rare to get a classic text book supercell or HP in new zealand? or is it possible under the right conditions?
Yes. Rare supercell thunderstorms occur during down the west of the country every winter/spring in the unstable westerlies. They are high shear low CAPE storms but can produce tornadoes/severe wind/severe hail.
03Stormchaser wrote:
Fantastic shot here from David Hardy on Facebook.
You can see the RFD cut in the cloud there.
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Re: Widespread Storms, South Island 23/2/14

Unread post by Thunder »

I was at home during this whole time, what a bugger eh? Good that Steve got onto it. Some wicked photo's out there!
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Re: Widespread Storms, South Island 23/2/14

Unread post by 03Stormchaser »

Forgot I took this image on my phone on this day.
Wallcloud.jpg
Its actually from the first cell that came cross from the West then became absorded by the larger cell moving up from the south. At the time I thought it could have been a wall cloud but decided it wasnt and headed south to what looked better on the radar. Now considering what happened I wonder if it was? This photo would have been taken near the old west coast road (Halket) looking North across the Waimakariri River (the reason why I coundnt get closer) at the back of this storm that Richard posted: http://www.weatherforum.org.nz/phpBB3/d ... &mode=view
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Re: Widespread Storms, South Island 23/2/14

Unread post by Richard »

Fascinating photo Steve,i think you are right too,that cell was noted by the MS's chart as moving east then to be absorbed into the main storm.
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Re: Widespread Storms, South Island 23/2/14

Unread post by Storm Struck »

Just came across this really close video of the tornado, you really cant get any better than this especially for NZ standards of nado's.
If I was filming or game enough to be filming there would be a few sharp words in it and fear/excitement.
http://www.youtube.com/watch?v=EVELm-d7KGA
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Re: Widespread Storms, South Island 23/2/14

Unread post by Orion »

Very good - thanks, Jason!
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