T-storms risk - Sat 22 Nov

[Razor]

Wow, metservice really going to town for severe storm risk tomorrow in Canterbury. My kids have their School Fair tomorrow. Yikes

[Bradley]

Yep,looks to be a better setup then Wednesday's event which wasn't half-bad at all, here's hoping!!

[Richard]

Great day to be at John's place ,just what the doctor ordered

[mikestormchaser]

The jet is there tomorrow over Canterbury with winds at upper levels at 45 to 55 knts
I also see a convergance zone aswel with the southerly change so they are two triggers.
But the 500mb temp isnt actually that cold tomorrow so will be interesting to see if things do get going.

[NZ Thunderstorm Soc]

Looking good for tomorrow's development from here, if we all come and meet and discuss.
From 2pm, I plan the meet for people. If anything interesting happens , we can go from here.
..or stay here and watch the development from here.

[trickytiger]

Good day for it tomorrow if anything happens as I have the day of and can put a full tank of gas in the car if things look good anywhere

[Tornado Tim]

Me and Andy Downs where discussing this event in quite some detail this afternoon from the Severe Convection Desk at Metservice (Last day of the New Zealand Met Conference).

Some very big considerable numbers in the ECMWF for favourable storm development. We were discussing the storms that you could get tomorrow could be linear orientated and pose the risk of strong straight line winds (this may very well be highlighted in the evening outlook update).

There is some variation in the models atm, when the southerly change is expected to come in, UKMO showing that it will come in early, GFS slightly earlier around 2-3PM and ECMWF around 4-5PM. With more weight being put on the ECMWF.

[Dean.]

Looks like a strong southerly buster front...will find a good position for pics!

[NZstorm]

Canterbury is notoriously unreliable for storms when the instability hinges on low level moisture. But the upper level lapse rates do look good at 7C and also good diffluence aloft for forcing. The surface southerly buster will need to lift the surface moisture to level of free convection, will be interesting to see if this set up comes off. Surface temps need to reach about 26C and surface moisture not mix out too much.

[Manukau heads obs]

wow Tim, sounds you like you would have been in your element

[Tornado Tim]

wow Tim, sounds you like you would have been in your element

I tell you what, whenever I go there, I just ache to become a Meteorologist.
We'll have to have a catchup sometime soon, haven't seen you and the fellow weather mates in a while. Perhaps a North Island one before the one in Welly?

Yea the NE, NW flow forecast will be interesting to see how it pans out, just very much depends where the centre of the low pressure system will be.
If a moderate NE comes in, you guys in CHCH will have a good chase day that's for sure, I wish I was there... Been missing the decent Thunderstorms that are chase-able.

[Powermad]

I'll be on the road from 2:30 after an appointment.

[Nev]

Thought it might be worth recording last night's update for today…

MetService - Thunderstorm Outlook

Valid to: Noon Saturday 22 Nov 2014

Issued at: 8:35pm Friday 21 Nov 2014
Updated at 8:35pm Friday

A frontal system is forecast to move across the South Island during the morning,while a low moves across Westland and Canterbury and deepens. Heavy rain is forecast for the west of the South Island and Southern Alps, along with northwest gales for central parts of New Zealand and there is a SEVERE WEATHER WARNING and WATCH in force for this event. There is a high risk of elevated thunderstorms from northern Fiordland to Buller and western parts of Nelson as well as the Southern Alps, including the Otago and Canterbury headwaters. Rainfall rates in these areas are likely to reach 15 to 25mm/hr or possibly higher about the ranges. A lesser risk of thunderstorms extends from southern Fiordland to the Canterbury foothills, the remainder of Nelson, western Marlborough and the Horowhenua Kapiti Coast.

A strong southerly change is forecast to cross North Otago late morning to reach South Canterbury around midday or more likely early afternoon. There is a low risk of thunderstorms triggering over North Otago and South Canterbury up to Ashburton during this time, although this risk is expected to rise significantly after midday over Canterbury.

No thunderstorms expected over the remainder of New Zealand.

MetService T-storm Outlook Map - Oct 22, am.jpg

Valid to: Midnight Saturday 22 Nov 2014

Issued at: 9:05pm Friday 21 Nov 2014
Updated at 9:05pm Friday

The frontal system moves across central New Zealand in the afternoon, and there is a moderate risk of elevated thunderstorms over northern Westland, Buller,western parts of Nelson and Taranaki, with localised rainfall rates of 15 to 25mm/hr. There is a lower risk of a few thunderstorms over the remainder of Westland, the Southern Alps, Nelson and western Marlborough during the early afternoon and from Kapiti up to Waikato during the afternoon and evening, as depicted on the chart.

The deepening low is forecast to move east of Canterbury during the afternoon,with a very strong southerly change expected to move through the region in its wake. A combination of warm temperatures prior to the change, and cool temperatures in the upper atmosphere, brings a high risk of thunderstorms to Canterbury in the afternoon. These storms may produce brief heavy rain, hail of 10 to 20mm diameter, and strong wind gusts of 90 to 110 km/h. In addition, there is a low risk of these storms becoming SEVERE, producing damaging wind gusts in excess of 110 km/h, large hail with diameter in excess of 20mm, and the chance of a small tornado. As the southerly change moves through Marlborough and onto southern Wairarapa late afternoon and evening, the potential for thunderstorms lessens.

No thunderstorms expected over the remainder of New Zealand.

MetService T-storm Outlook Map - Oct 22, pm.png

[Richard]

Wondering how much this mornings forecast will change from last nights.

The big difference to Wednesday is there is not the strong NW wind,blowing a mod NE here this morning

[melja]

Crazy rain here on the coast in kumara junction with 12mm/h for the last 3 hours with a strong Nw, still no thunderstorms here yet.

[Manukau heads obs]

good luck and stay safe to all the chasers

[Chris Raine]

Travelling Hokitika to Oamaru later this morning.Will see what develops.No thunderstorms in Hokitika but lightning detector picking activity off shore in Tasman Sea.Rain has eased last 15 minutes

[Nev]

Here's this morn's update. Canterbury's severe risk has been upgraded to medium…

MetService - Thunderstorm Outlook

Valid to: Midnight Saturday 22 Nov 2014
Issued at: 8:29am Saturday 22 Nov 2014

A frontal system is moving across central New Zealand this morning and afternoon bringing a burst of heavy rain and northwest gales to some places, as detailed in the latest SEVERE WEATHER WARNING AND WATCH. There is a moderate risk of thunderstorms from northern Westland to western Nelson this morning and afternoon, with a lesser risk extending from South Westland to the remainder of Nelson and western Marlborough. A low risk of thunderstorms then extends over western and central parts of the North Island from Kapiti to Waitomo this afternoon and early evening.

A deepening low moves east of Canterbury today. In its wake, a very strong southerly change is forecast to move northwards through Canterbury and Marlborough late from later this morning to early this evening. This change is likely to be squally with a low risk of thunderstorms. However, the combination of warm temperatures prior to the change, and cool temperatures in the upper atmosphere,elevate the risk of thunderstorms in Canterbury to high this afternoon. These thunderstorms may produce brief heavy rain, hail of 10 to 20mm diameter and strong wind gusts of 90 to 110 km/h. In addition, there is a moderate risk of these thunderstorms becoming SEVERE, with hail diameter in excess of 20mm,damaging wind gusts in excess of 110 km/h, and the chance of a small tornado.

No thunderstorms expected over the remainder of New Zealand.

MetService T-storm Outlook Map - Oct 22.png

[03Stormchaser]

The one day to have my stags party....

[Richard]

The one day to have my stags party....

Easy,take the boys on a chase/pub crawl

[mikestormchaser]

Breezy but not strong NW here in rolleston.. im not totally convinced on todays set up but if it pulls off will be an interesting day.

[Razor]

On port hills, its hot sunny....and just gone NE!

[03Stormchaser]

Breezy but not strong NW here in rolleston.. im not totally convinced on todays set up but if it pulls off will be an interesting day.

Just been looking over the models, unsure it screams out such a high risk day, does look like it may come a bit later than the last couple days predicted. Upper air is pretty warm

[mikestormchaser]

26C out there and climbing, getting warm as!!! a light NW here

[Dale]

As Melja mentioned earlier, it's been mental rain here in Greymouth all morning with a few doozy close lightning strikes around an hour ago.. so it looks promising for you guys over there. Enjoy ya meeting