South Island Storms - 5/12

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Re: General December Weather

Unread post by darcyplumb »

Could be an interesting day ahead on the Canterbury Plains. Is anyone planning on chasing? I’ll be chasing from the window at work 😢
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Re: General December Weather

Unread post by Dean. »

darcyplumb wrote:Could be an interesting day ahead on the Canterbury Plains. Is anyone planning on chasing? I’ll be chasing from the window at work Image
Will keep an eye out while watching the NZ Heartland game ImageImage

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Re: General December Weather

Unread post by darcyplumb »

Dean. wrote: Sun 05/12/2021 09:29
darcyplumb wrote:Could be an interesting day ahead on the Canterbury Plains. Is anyone planning on chasing? I’ll be chasing from the window at work Image
Will keep an eye out while watching the NZ Heartland game ImageImage

Sent from my SM-A226B using Tapatalk
Should be a great game! Bathurst on today too if you’re into your Motorsport.
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Re: General December Weather

Unread post by mikestormchaser »

MS have put a strong risk out for Canterbury this afternoon,
It's an interesting set up, I prefer more colder air aloft however with such high DP around as of late the surface conditions might over ride the warmer air on the coast today.
Quite strong shear today so good forcing if we do get storms.
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Re: General December Weather

Unread post by darcyplumb »

mikestormchaser wrote: Sun 05/12/2021 09:42 MS have put a strong risk out for Canterbury this afternoon,
It's an interesting set up, I prefer more colder air aloft however with such high DP around as of late the surface conditions might over ride the warmer air on the coast today.
Quite strong shear today so good forcing if we do get storms.
Our first decent storm chance of the season.
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South Island Storms - 5/12

Unread post by Tornado Tim »

Looks like some storms could possibly develop along the cold front as it passes up the South Island:

Metservices Outlook for today:
Metservice wrote:A front moves slowly northwards over Westland and the northwest of the South Island during today, while another front is expected to move over the south of the South Island this morning and then quickly up the east of the South Island in the afternoon and evening.

There is a low risk of thunderstorms about central and northern Westland, Buller and western Tasman associated with the leading front.

In the east of the South Island and associated with the following front, there is a moderate risk of thunderstorms for North Otago during the afternoon, and for parts of Canterbury in the afternoon and evening, as indicated on the chart. Any thunderstorms that occur will mostly have the potential to bring localised heavy rain with intensities of 10 to 25 mm/h, strong wind gusts of 90-110 km/h and hail 10 to 20 mm in diameter. However, in Canterbury south of about Rakaia there is a moderate risk of SEVERE thunderstorms developing, bringing a risk of damaging winds gusting greater than 110 km/h and also the possibility of small localised tornado. A lower risk of thunderstorms extends inland from Clutha to North Canterbury.

No thunderstorms or significant convection expected in other areas of New Zealand during this period.
image.png

Looking at the forecast sounding, there is a good amount of shear indicated by the GFS, key will adequate forcing. The GDPS model has this as a marginal setup with warmer upper temps and wind less variance with height.
image.png
Looking like a fairly cloudy day down south, any sunshine would be of benefit ;)
image.png
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Re: South Island Storms - 5/12

Unread post by Chris W »

The uppers aren't great but most other things seem to be, particularly at the surface where it's reasonably humid NE with some intense sun just poking through. Timing of the front is looking best for South Canterbury hence the greater risk there.
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Re: South Island Storms - 5/12

Unread post by spwill »

The weather stays humid here this week but the rain struggles to come north, the mainly dry trend to continue here through this week.

Edit, this in the wrong thread
Last edited by spwill on Mon 06/12/2021 08:54, edited 1 time in total.
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Re: South Island Storms - 5/12

Unread post by darcyplumb »

Decent spillover rain in Ashburton currently. Will this have any impact on thunderstorm development later on?
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Re: South Island Storms - 5/12

Unread post by dogmelon »

darcyplumb wrote: Sun 05/12/2021 12:18 Decent spillover rain in Ashburton currently. Will this have any impact on thunderstorm development later on?
Nah.
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Re: South Island Storms - 5/12

Unread post by Razor »

Keen NE at my back on Sugarloaf, blowing towards this
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Re: South Island Storms - 5/12

Unread post by Razor »

Rapid and quite explosive development
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Re: South Island Storms - 5/12

Unread post by NZ Thunderstorm Soc »

Looking promising up there but nothing much down here with flat cloud and the occasional throwover shower from the west. Light NW although NE earlier.
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Re: South Island Storms - 5/12

Unread post by NZ Thunderstorm Soc »

Southerly change through here just after half past three pm.
Just some low cloud and a bit of a wind change. A weak gust front up along the foothills.
More constant rain from then on mostly from the N west.
See some red blobs on the Hindon radar down Otago way.
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Re: South Island Storms - 5/12

Unread post by Orion »

Ya, wind just beginning to get gusty and chilly here, cloud appears to be lowering and it's getting quite dull. 19°C.
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Re: South Island Storms - 5/12

Unread post by NZ Thunderstorm Soc »

All over bar the shouting. Just an ordinary southerly change down here. I blame climate change. It's wonder the MS still have their STW out?
I see EC have a river warning out for the Rakaia and Rangitata Rivers.
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Re: South Island Storms - 5/12

Unread post by Razor »

26 degrees at 5:30pm and a balmy NE breeze back
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Re: South Island Storms - 5/12

Unread post by Chris W »

Going out to sea, the fizz is strong with this one.
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Re: South Island Storms - 5/12

Unread post by Orion »

Light rain here at present but there's almost a sense of 'holding its breath' as if there's going to be a downpour or a squall or something, atmosphere feels quite oppressive 0_o
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Re: South Island Storms - 5/12

Unread post by NZ Thunderstorm Soc »

I think this an non-event and postings of today should be put in the December weather thread?
MS have dropped their STW warning.
Didn't look any good here today with constant cloud covering hindering surface warmth. Looked better yesterday.
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Re: South Island Storms - 5/12

Unread post by darcyplumb »

NZ Thunderstorm Soc wrote: Sun 05/12/2021 18:37 I think this an non-event and postings of today should be put in the December weather thread?
MS have dropped their STW warning.
Didn't look any good here today with constant cloud covering hindering surface warmth. Looked better yesterday.
As soon as the spillover rain came over and set in I knew it was all over. Far too much cloud cover here.
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Re: South Island Storms - 5/12

Unread post by NZ Thunderstorm Soc »

darcyplumb wrote: Sun 05/12/2021 18:49 As soon as the spillover rain came over and set in I knew it was all over. Far too much cloud cover here.
I thought it may of developed, say, north of the Rakaia river and into North Canterbury with the wind-change, rather down here because of the constant cloud cover and throwover rain from the West Coast.
It's been warmer up there today than down here as well.
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Re: South Island Storms - 5/12

Unread post by Orion »

Wind has strengthened and rain is heavier now.
14°C.
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Re: South Island Storms - 5/12

Unread post by spwill »

Yes, spill over rain in the afternoon dampens down the instability.
The set ups where cold upper level air is the major ingredient are more reliable for thunderstorm development especially in December.
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Re: South Island Storms - 5/12

Unread post by NZ Thunderstorm Soc »

The dynamics for producing today's thunderstorm forecast were there, but the factors that evolved from constant cloud cover and overthrow rain falling, which is still going on despite the cold southerly coming through and lack of sunshine for ground heating purposes, hindered today's chances of thunderstorm development over the Canterbury Plains today. We like the fascination of a good thunderstorm but in some ways, who wants hail to damage crops, etc.. :-k :eek:
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