Some good local thunderstorm case-studies?

[xealeel]

Hi all
I am just starting out on a PhD in Christchurch studying locally-initiated thunderstorms in New Zealand – looking specifically at how the WRF-ARW mesoscale model can be adapted for the NZ situation – and am currently searching for some case-studies around New Zealand. I've found a few possibilities: Canterbury (27 Oct 2002; 17 Jan 2009; 25 Mar 2012), Hawkes Bay (5 Dec 2011), the Waikato (27 Jan 2010), Wellington/Hutt/Porirua (11 Feb 2007), Kapiti (15 Feb 2007). However, I was wondering if any of you would be willing to share some of your expertise with me – either regarding specific storms I've already mentioned, or whether anyone had any other memorable storms from around the country to suggest?

I have some pretty strict criteria in that I am only looking for storms that have local scale triggers (such as land-sea breezes, surface heating) ie NOT associated with troughs or fronts. Not so important is that I am keen on relatively recent ones in order to utilise more data for verification (for example, any storm subsequent to September 2000 can utilise lightning data; any storm on the West Coast after 23 Nov 2011 can utilise their new radar data).

If there's a really good example in one of the areas I've already got a casestudy for, I'd still love to hear about it. However, what I would really like is to get one or two more good examples from elsewhere in the country (eg Southland, West Coast, Nelson, Taranaki, Northland/Auckland, East Cape) which is proving to be a bit difficult (mainly because most of the ones that I find mention of are associated with troughs/fronts, and available recent historical thunderstorm data seems to be pretty sketchy). Also, while I have pretty good knowledge of the weather around New Zealand, there's nothing like local knowledge and so any personal stories from any of these storms would be gratefully received.

Many thanks in advance for all your comments and suggestions.
Kerryn

[spwill]

I have some pretty strict criteria in that I am only looking for storms that have local scale triggers (such as land-sea breezes, surface heating) ie NOT associated with troughs or fronts.

Those localised seabreeze/daytime heating storm events will be associated with trough/ frontal activity.

[Tornado Tim]

Those localised seabreeze/daytime heating storm events will be associated with trough/ frontal activity.

Yes Sea breezes are also known as sea breeze fronts where the warmer air rises above the cooler more saturated air from the sea. So that is a trigger mechanism.

[xealeel]

yes you're right. should have said 'not embedded in synoptic-scale troughs or fronts'. I'm after smaller scale processes, such as sea breeze fronts.

[Manukau heads obs]

sea breeze convergent thunderstorms are relatively commen in this area over the years
They will first form here on the west coast then the SW sea breeze is often stronger than the NE sea breeze, and so the convergence line moves NE and then finally gets an energy boosts over the auckland isthmus region
the other scenario is a SE flow then a sea breeze hitting that , with the Pukekohe hill/Bombay hills being the forcing trigger...in this case, often the SE wind will push the storms NW, onto the Glenbrook then Pollok areas...been some real doozy thunderstorms over the years in that situation (not for a while mind you)

[spwill]

I'm after smaller scale processes, such as sea breeze fronts.

There will always be some troughing in place.

[xealeel]

sea breeze convergent thunderstorms are relatively commen in this area over the years
They will first form here on the west coast then the SW sea breeze is often stronger than the NE sea breeze, and so the convergence line moves NE and then finally gets an energy boosts over the auckland isthmus region
the other scenario is a SE flow then a sea breeze hitting that , with the Pukekohe hill/Bombay hills being the forcing trigger...in this case, often the SE wind will push the storms NW, onto the Glenbrook then Pollok areas...been some real doozy thunderstorms over the years in that situation (not for a while mind you)

thanks for that - looks like a fantastic example in archives on 10 February 2007 (thanks to David for link!)

[Tornado Tim]

I would also have a look at the archives for 2010, particularly in late January. That has the forecasted charts and reports from that outbreak then.

[Weather Watcher]

There was a good day of afternoon thunderstorms in Auckland on 17 February 2012, which pulsed along the sea breeze convergence zone all afternoon and evening, and produced surface flooding in western Auckland.

Another day worth investigating in Canterbury is 14 December 2009. This day produced several big storms, including one long-lived storm in South Canterbury with 2-3cm hail and a tornado near Methven.

The period 25-30 January 2010 was notable for many severe storms around the central North Island. There was also a good day of severe storms in Gisborne/Hawkes Bay on 22 January 2010.

[spwill]

There was an interesting storm event over Taupo 2006, some discussion here http://www.weatherforum.org.nz/phpBB3/v ... ilit=taupo

[sthguy]

Pm me.

[NZstorm]

There was an interesting summer convective storm over Southland on the afternoon 15th December 2005 which produced a severe wind event (maybe tornado) and large hail.

Keep in mind the the local scale surface trigger is only part of the thunderstorm development story. There has to be an upper level synoptic scale feature as well. Sometimes summer storms can actually be triggered by the approach of the upper level system (shortwave trough) rather than just sea breeze convergence. Any study of storm development has to take in the whole picture to be meaningful.

[spwill]

Keep in mind the local scale surface trigger is only part of the thunderstorm development story. There has to be an upper level synoptic scale feature as well.

The heating /seabreezes are almost a daily occurrence through summer but with only a few thunder days, I think the upper level environment is the more significant factor here in NZ.

[sthguy]

There was an interesting summer convective storm over Southland on the afternoon 15th December 2005 which produced a severe wind event (maybe tornado) and large hail.

Keep in mind the the local scale surface trigger is only part of the thunderstorm development story. There has to be an upper level synoptic scale feature as well. Sometimes summer storms can actually be triggered by the approach of the upper level system (shortwave trough) rather than just sea breeze convergence. Any study of storm development has to take in the whole picture to be meaningful.

Although the weather was warm and summery for much of the month, air at higher levels was
slightly cooler than usual and very unstable. This combination brought localised heavy afternoon
and evening showers on many days. These showers became widespread from the 14th to the 21st
as a shallow low moved slowly across the South Island, and cumulative rainfall totals brought
rivers to flood levels.
Some of the storms were severe, with reports large hail and damaging wind gusts {5th, inland of
the city} wind damage & funnel clouds, hail damaging crops and vehicles {14th, Heddon Bush}
and cloudbursts bringing flooding {20th Invercargill, Queenstown; 21st areas north and
northwest of Gore}

[xealeel]

thanks for all your suggestions and comments.