NZ Weather Forum

I see it has trended further south all the time
bit has weakened
M/S warning track did not have that curve

I don't need my detector to see the flashing

Come to life again I see outer gulf...

Wow over 1100 strikes in the hour going by Blitzortung.....

Overnight low was a warm 16.5 here, some moderate rain starting now.

Just heard a small rumble of thunder

1 flash and loud thunder just now.

Decent crack of thunder in Auckland CBD just now

Had a lightning flash and loud thunder here

Plenty of activity showing north of Ak

what I would like to know is:
even though they are elevated CB's , they still did the usual die off over land
(its back again now over the open ocean to the east)

Thunder here, very distant though.

Manukau heads obs wrote:what I would like to know is:
even though they are elevated CB's , they still did the usual die off over land
(its back again now over the open ocean to the east)

It went across Northland this morning but yes the line last night died near the west coast.

just a few rumbles here last 30 mins

interesting how the M/S tracker picked up strikes to the north of the line...eg right up to the bay of islands (re Alan;s report) but blitzortung did not pick those up?

Heard around 10 rumbles here between 8am and 9am. None of them were overhead though.

Manukau heads obs wrote:interesting how the M/S tracker picked up strikes to the north of the line...eg right up to the bay of islands (re Alan;s report) but blitzortung did not pick those up?

I have noticed blitzortung misses plenty but it is still great to have it.
More thunderstorm activity heading for Northland

9.35 AM Metservice update

Valid to: Midnight Wednesday 29 Oct 2014

Issued at: 9:35am Wednesday 29 Oct 2014

A frontal system is expected to move eastwards over northern New Zealand this morning and early afternoon. There is a moderate risk of thunderstorms with the passage of this front from Northland down to Auckland and Coromandel Peninsula.These thunderstorms may produce localised heavy rainfalls with intensities of 10-25mm per hour, hail and strong winds gusts. There is a low risk a few of these thunderstorms may become SEVERE over Northland and northern Auckland (north of about Helensville), producing large hail, greater than 20mm in diameter,and strong winds gusting greater than 110km/hr. There is an additional lower risk of one or two localised downpours giving 25-35mm/hr and an outside risk of a small tornado.

A cold front moving over the upper South Island this morning is expected to move across the North Island this afternoon and evening, this front is followed by a very unstable airmass. In the west of the South Island from western Nelson down to Fiordland, there is a moderate risk of thunderstorms, which diminishes about southern Westland and Fiordland this evening. While for central and western areas of the North Island from southern Auckland and Coromandel Peninsula to the central high county and down to the Kapiti Coast, there is a low probability of thunderstorms this afternoon with cold front, but increases to moderate in the evening as the unstable airmass moves onshore. These thunderstorms are likely to bring localised heavy rain with intensities of 10 to 20mm per hour and strong wind gusts of 90 to 110 kilometre/h. Hail is also likely.

During the afternoon a southerly change is expected to move over Southland and Otago. There is a moderate risk that thunderstorms could develop on this change over Southland and eastern Otago (including Dunedin). If these thunderstorms occur they are likely to bring localised heavy rain with intensities of 10 to 20mm per hour and hail.

Manukau heads obs wrote:interesting how the M/S tracker picked up strikes to the north of the line...eg right up to the bay of islands (re Alan;s report) but blitzortung did not pick those up?

After going to the Metservice office a month or so ago, I learnt a bit more about how the Viasala Lightning detectors work.
They use a combination of TOA/TOGA and Triangulation to get Lightning positions.
So for example if a strike cant be positioned by the TOA/TOGA algorithms it gets handed off to the Triangulation location algorithms which therfor look at the left and right H-fields signals in accordance to bearing North.
Blitzortung doesn't do this, the main reason being accuracy, Triangulation yields a much lower accuracy field.

Another thing, Blitzortung detectors will sometimes go into "Interference mode" if storms come too close.
This is intentional to stop the server being flooded with signals which cant be processed (the closer you are to a storm, the more finer grain discharges get picked up (ie. stepped leaders etc), those signals cant be cross referenced back unless there is multiple stations within 1 KM of strike).
Alans station would have probably gone into "Interference mode", which would have dropped his station out and there would'nt have been enough stations that picked up the strike to participate.
This is why we want...... need new stations.

Another thing is the Windows tracker is more prone to go into Interference mode more often than the server operated tracker program is, there are multiple phases the server tracker will go into whenstuff comes close so its more likely to get a position out of it.
Every participant who has a system Green should consider using the compiled server tracker program: Thread on it here

yeah, I suspected the interference mode was why it did not pick up the strikes close to alan's detector

Just had a small tornado through Paroa near Greymouth about 45 minutes ago .Hit the West Coast Regional Council building ripped an air conditioning unit off the building and knocked over a row of Porta Loos !(nobody inside! ).They are stored there for emergencies

Chris Raine wrote:Just had a small tornado through Paroa near Greymouth about 45 minutes ago .Hit the West Coast Regional Council building ripped an air conditioning unit off the building and knocked over a row of Porta Loos !(nobody inside! ).They are stored there for emergencies

That's a bit of a..... shitty.... situation

They are stored there for emergencies

oh the Irony

we have "torrential drizzle" here now on the back side of the front...and the sky is looking brighter...

A line of Tstorms crossing Northland now, Whangarei would be a good spot to be right now for some lightning

can see blue sky out to my SW now