Heavy rain/tornado/snow/wind event. 18-21 November

[NZstorm]

North Island's turn for thunder/hail tomorrow.

500mb polar vortex tells the story! Tuesdays chart.

[David]

Collected 12mm rain here in the early hours, was a very heavy fall just after 4am.

[Dean.]

https://www.webcams.travel/webcam/fullscreen/1516045422

A good coating at Mid Canterbury's Lake Camp 700 metres

[jamie]

Did MetService warm of possible tornado based on radar with the severe thunderstorm warning yesterday. And then with reports of tornado make a note that this is a particularly dangerous storm with a reported tornado?


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[spwill]

Queenstown is currently 0.9C with precipitation, amazing weather for mid November.

Snow level down to about 350m

[spwill]

Sleet/ wet snow in Queenstown now, 0.4C

[Nev]

Did MetService warm of possible tornado based on radar with the severe thunderstorm warning yesterday. And then with reports of tornado make a note that this is a particularly dangerous storm with a reported tornado?

There were actually 4 Severe Thunderstorm Warnings issued for Canty/Otago by MS yesterday arvo. I only managed to cache their 3:34pm Severe Thunderstorm Warning, their 3:26pm Thunderstorm Outlook and their 2:57pm Severe Thunderstorm Watch, all of which mentioned possible tornadoes.

MetService - Severe Thunderstorm Watch

MetService Severe T-Storm Watch map - Nov 18, 2.57pm.png

Issued by MetService at 02:57 pm Sunday 18 November 2018
Valid until 09:00 pm Sunday 18 November 2018
This watch affects people in the following weather forecast districts:
Canterbury Plains
Canterbury High Country
North Otago

Thunderstorms have developed about south Canterbury early this afternoon and are expected to move northwards through mid Canterbury during the afternoon and evening. There is a moderate risk some of these thunderstorms could become SEVERE producing large hail 20 to 30mm in diameter, strong winds gusting greater than 120 km/h and localised damaging tornadoes.

Large hail can cause significant damage to crops, orchards, vines, glasshouses and vehicles, as well as make driving conditions hazardous. The strong wind gusts and possible tornados may cause some structural damage, including damage to trees and power lines, and make driving hazardous. If any tornados occur, they will only affect very localised areas.

Should severe weather approach or if you feel threatened, take shelter immediately.

Note: A Severe Thunderstorm Watch means conditions are favourable for severe thunderstorms in and close to the watch area. People in these areas should be on the lookout for threatening weather conditions and monitor for possible Severe Thunderstorm Warnings.
...

MetService - Thunderstorm Outlook

Valid to: Midnight Sunday 18 Nov 2018
Issued at: 3:26pm Sunday 18 Nov 2018

Updated Sunday afternoon to add a moderate risk of SEVERE thunderstorms for Canterbury.

A front over Taranaki is moving slowly northwards. A series of fronts are expected to move over the southern South Island during the day. Meanwhile, upper temperatures over the South Island should cool today, making conditions more unstable.

There is a low risk of thunderstorms over northern Taranaki and Waitomo this morning and early afternoon associated with the North Island front.

For the South Island, there is a moderate risk of thunderstorms this afternoon and evening about Fiordland, Southland, eastern areas of Otago and Canterbury south of about Banks Peninsula. These thunderstorms if they occur are likely to be accompanied by localised heavy rain and hail. Additionally about south and mid Canterbury there is also a moderate risk of SEVERE thunderstorms developing. These SEVERE thunderstorms could bring large hail 20 to 30mm in diameter, strong winds gusting greater than 120 km/h and also the possibility of localised damaging tornadoes.

A lower risk of thunderstorms extends into inland areas of Otago and further north through the remainder of Canterbury.

No other areas of severe convection or thunderstorms are expected.

MetService T-Storm Outlook map - Nov 18, 3.26pm.png

MetService - Severe Thunderstorm Warnings

Canterbury Radar Area

MetService Severe T-Storm Warnings map - Nov 18, 3.34pm.gif

SEVERE THUNDERSTORM WARNING
TOP PRIORITY FOR IMMEDIATE BROADCAST

Issued by MetService at 03:34 pm Sunday 18 November 2018.
Valid until 04:22 pm Sunday 18 November 2018.

This warning affects people in the following local government areas:
ASHBURTON.

At 03:22 pm, MetService weather radar detected severe thunderstorms near ASHBURTON, WINCHMORE, HINDS, TINWALD and WESTERFIELD.

These severe thunderstorms are moving towards the east, and are expected to lie near ASHBURTON, WINCHMORE, THE ASHBURTON RIVER MOUTH, TINWALD and DROMORE at 03:52 pm and near ASHBURTON, RAKAIA, CHERTSEY, THE ASHBURTON RIVER MOUTH, SEAFIELD, PENDARVES and DROMORE at 04:22 pm.

These thunderstorms are expected to be accompanied by very heavy rain, large hail and possible tornadoes.

...

Other 3 Severe Thunderstorm Warning graphics:

[mikestormchaser]

Keep watch today to as the 500mb temp is -32 over the south island. Just need a trigger

[NZ Thunderstorm Soc]

Hole in the sky here with the sun shining showing very icy looking cloud all around.

[Razor]

Seems to me things are running out of steam as they approach Chch. Kinda similar to yesterday. Just a hunch from observing both the radar and the skies aloft

[Thunder081]

Looking SW from Levin and can see cloud buildups starting over Marlborough

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[Thunder081]

And also another one offshore west of Levin

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[Dean.]

No heavy rain watch for Eastern Canterbury as yet...GFS (Metvuw) have amped up moisture levels right through until Tuesday night here

[Richard]

It's a day where it's will it?, or won't do it?,. This is looking NE

[Richard]

Looking west there's been this shower in and around that area for about an hour or so

IMG_20181119_131934.jpg

[Richard]

East

IMG_20181119_133814.jpg

[snowstormwatcher]

Heavy shower here with small hail. Temp dropped to only 5c.

[Richard]

IMG_20181119_134242.jpg

This heavy shower would hail too, WSW along the foothills

[NZ Thunderstorm Soc]

A southerly squall moved through here at 1325hrs delivering strong winds, heavy rain and wintery hail. This moving into towards the 4 Peaks (where I heard 2 rumbles of thunder) and Mt. Peel area. Temperture drop of 5C with this, but when it was allover, the sun came out and you could see steam coming off the roofs of houses nearby.

[Razor]

Seems to be fizzing again, much promise but nothing but a couple of brief showers so far round here. Rain radar looks to be showing weakening trend?

[Richard]

Just getting first shower and of pea size hail now

[Razor]

Short lived heavy shower here

[Chris W]

A pretty hefty shower going through town now, making rush hour traffic drive quite well!

[tich]

A pretty hefty shower going through town now, making rush hour traffic drive quite well!

Just when I have to bike through it. Weather's been playing cat and mouse with central Chch all day.

[Thunder081]

This was taken from Levin at 12:30pm ish