South Island Thunderstorms 30th December

[NZ Thunderstorm Soc]

There maybe some thunderstorms over Westland tonight and coastal Otago way tomorrow.
Not looking like much at the moment but according to MetService's forecast's they are quite hopeful
When they say 'Thundery showers' sort of lessens the thunderstorm risk, I reckon.

[03Stormchaser]

Sounds like three of us will be heading south tomorrow, probably head to just south of Timaru, Watch the radar etc then figure out the target area once storms start building. Will have another look of the models in the morning but it wouldn't surprise me if Metservice don't increase the thunderstorm outlook further north.

[NZstorm]

It looks a robust set up for Dunedin(east Otago). The upper levels are not that cold for Dunedin but the forecast dp is 13C.
The main weakness is the possibility of mid level cloud which will cut down the heating.
Upper flow is great with the Sub Antartic jet over the South Island.
Could be some hail as well.

[NZstorm]

250mb jet stream forecast for tomorrow.

For Canterbury you wanted that jet stream a bit further north.

[03Stormchaser]

Update this evening from Metservice, not surprised to be honest.

In the North Island, the frontal band should move eastwards across the North Island in the afternoon and early evening. The risk of thunderstorms generally eases in the afternoon, however there is still a low risk of thunderstorms from Hawkes Bay, Tongariro and North Taranaki northwards through the afternoon and early evening as indicated on the chart. Localised heavy rain will accompany any thunderstorms that do occur.

On the South Island west coast, a moderate thunderstorm risk continues about Westland in the afternoon, and Buller until evening, with thunderstorms embedded within areas of rain.

In Otago and Southland, scattered heavy showers and thunderstorms are expected during the afternoon, producing locally heavy rain and hail. Hail of 10-20mm (1-2cm) diameter can be expected, with a low risk of larger damaging hail.

Further north, there is a lower risk of thunderstorms about coastal parts of Canterbury and Kaikoura during the evening and at night associated with a southerly wind change.

No other thunderstorms or severe convection expected over New Zealand on Sunday afternoon and evening.

[NZstorm]

The UKMet is showing a coastal southerly over south Canterbury later in the day.

[03Stormchaser]

The UKMet is showing a coastal southerly over south Canterbury later in the day.

Yea noticed that, almost seems like the odd-model-out!

[03Stormchaser]

Looks like the place to be will be inland Otago then south of Dunedin or even over Dunedin as the storm moves east. Looks like some very heavy rain will accompany those storms. I do think there is a good chance a storm will form in South Canterbury later in the day around Timaru

[Chris Raine]

I'm in Southland so will see what develops and let the forum know

[mikestormchaser]

high risk has spread up more towards the timaru area later in the day and into the evening. with a bigger low risk area covering more of Canterbury.
I wouldnt be at all surprised if Ashburton would be more in moderate risk, we know how these storms and systems can spread further north then inticipated.

cheers: mike

[NZstorm]

GFS Chart for Lifted Index and surface wind flows at 1pm

[mikestormchaser]

GFS Chart for Lifted Index and surface wind flows at 1pm

Yeah see that LI of -2 isnt to bad really and thats more towards the ashburton area and a pool if instabilty also in south otago with that gap of -0 in between

[03Stormchaser]

Valid to: Midnight Sunday 30 Dec 2012

Issued at: 9:09am Sunday 30 Dec 2012

Over the North Island, a frontal band should move eastwards off Northland and Auckland by afternoon and proceed across Bay of Plenty and northern Gisborne this afternoon and evening. There is generally a low risk of thunderstorms with this front.

On the South Island west coast, a couple of cold fronts move north through the day with the second lying near Westport by evening. There is a moderate risk of thunderstorms mainly in the vicinity of each of these features - over Fiordland and Westland this morning and afternoon, and further north this evening.

In Southland, Otago, and as far north as south Canterbury, scattered heavy showers and thunderstorms are expected to develop late this morning and persist through this afternoon, producing locally heavy rain and hail. Hail of 10-20mm (1-2cm)diameter can be expected, with a low risk of larger damaging hail. These stotrms are expected to move offshore in the early evening.

Further north, there is a lower risk of thunderstorms about coastal parts of Canterbury and Kaikoura during the evening and at night associated with a southerly wind change.

Elsewhere, no thunderstorms or significant convection expected.

Sometimes I think metservice are reading my mind...

[Richard]

Good luck to those heading south hopefully we;ll see some good photos later.

[Thunder]

I'll be left behind in Chch, can't get away really with work stuff but goodluck to Steve, Mikey and Jase.

I'll be out later should things spread further north to BP.

[NZstorm]

I see the dewpoint in Mosgiel 15C. The moisture is there in east Otago this morning.

[Andy]

I keep your posted from Alex

[Chris Raine]

There are showers occurring from Cb Capillatus to the west of Thornbury currently

[Orion]

A little southerly wind-change here in the last half-hour;
temp down to 23.2 degrees;
some raggy-looking white cloud approaching from the south.

[Orion]

Light rain falling;
down to 20.4 degrees.

[Thunder]

Radar is picking up that southerly wind shift quite well, cool to watch.

Maybe it'll die away though before something else comes up later? Could actually be a good thing as it kicks the NW wind out've the way.

[CHCH Weather Chaser]

Yes it seems a southerly has snuck in early. Ash on 19. 29 locally here. 28 at airport. Few interesting clouds about even with humidity at 24%

Just hit magic 30. Although dirty cloud by sun atm and cloud increasing

[Orion]

17.9 degrees now.
Mustn't grumble

[Chris Raine]

Southerly change at Thornbury , moderate showers .

[03Stormchaser]

I not worried about this southerly at all, if you have a look the trough later in the day is the one to watch.