NZ Weather Forum

Interesting to see the Singapore flight avoiding TS and that active front in the Tasman - usually it's a straight NW flight path.

thats NZstorm's quote, not mine

NW wind ramping here quickly

NZstorm wrote: The jet stream provides the lift as well orographic effects of Alps.

Hows this ?

Yes,you can see that orographic effect of the Alps in that the lightning is not happening near the coast but along the Alps and to the east.

Thunder every minute here, currently in between sheffield and springfield. Although not seeing many visible strikes

I dont think i have ever seen the 3 south island rain radars pick up so much rain over the alps. These storms must be reaching a very high altitude and must be really saturated to be giving back echos over the most part of the south island.

Look at this front, Blitzortung !

Metservice data

50 mil plus and snow

Really long rumble of thunder here

Big thunder here in riccarton. Must be nuts in the hills. Still stuff all wind

That was a big zap on the radio and rumble of thunder. Thats the third period of NW thunder in a couple of months. How extraordinary.

another period of heavy rain, gusty wind and thunder rolling through at the moment.
recorded a station record high wind gust earlier in the arvo.

Thunder very close by now

Long rumbles of thunder here with a significant elongated thunderous rumble at the end.
One flash overhead, which scared the guttering guy who was measuring the guttering for replacement after being damaged in the "Big Blow" last month.

Richard wrote:

NZstorm wrote: The jet stream provides the lift as well orographic effects of Alps.

Hows this ?

Yes,you can see that orographic effect of the Alps in that the lightning is not happening near the coast but along the Alps and to the east.

The lightning is occurring over the sea west of the Alps as well.
Jet stream adds to the large scale ascent by divergence and speed shear aloft.
Jet stream also enhances the oroghrapic lift by reinforcing the NW flow at lower levels.

NZstorm wrote: The lightning is occurring over the sea west of the Alps as well.
Jet stream adds to the large scale ascent by divergence and speed shear aloft.
Jet stream also enhances the oroghrapic lift by reinforcing the NW flow at lower levels.

Thanks for explaining that Steven,such interesting weather today and now the wind has swung around to the NE with a steady rain

Yes I quite like that elevated thunder sound you get the thunder rumble then quiet followed by a dumping boom much different to the usual thunderstorm activity due to the travel of the lightning bolts im sure.
Last rumble I heard was 30 minutes ago not long after I had got home, so shes still at it hopefully see some flashes after dark maybe.

Speaking of which I am baffled with the MS thunder outlook for tomorrow? I would be putting out at the lowest a moderate risk but ceratainly a high risk over south Canterbury moderate up to Christchurch even provided the storms keep going after dark.
That hail will be up there in size again with possibly even slower storm movement than Saturday.
They speak of onshore winds down on the coast there yet its going to be onshore everywhere in Canterbury tomorrow.
Can we expect a nowcast I bet we will.

Storm Struck wrote:Yes I quite like that elevated thunder sound you get the thunder rumble then quiet followed by a dumping boom much different to the usual thunderstorm activity due to the travel of the lightning bolts im sure.

...yes Jase, the "dumping boom" seems to be much longer the your usual 'dump thunder' associated with a lower, long lightning strike. One clap, this afternoon, did result in a shuddering boom that did shudder the windows.

NZstorm wrote:

Manukau heads obs wrote:wouldnt be nice if that mid tasman front stayed like that as it crossed the north island

We seem to miss out on it here Brian. Typically weakens as it comes onto NI.

And dies altogether when it hits the Kaimai's

Storm Struck wrote:
Speaking of which I am baffled with the MS thunder outlook for tomorrow? I would be putting out at the lowest a moderate risk but ceratainly a high risk over south Canterbury moderate up to Christchurch even provided the storms keep going after dark.
That hail will be up there in size again with possibly even slower storm movement than Saturday.
They speak of onshore winds down on the coast there yet its going to be onshore everywhere in Canterbury tomorrow.
Can we expect a nowcast I bet we will.

MS will change the outlook in the morning id say jase, i wouldnt worry to much with there outlook tonight.

Wow, 27.4C at Kaikoura yesterday arvo, along with gusts to 111 km/h. Jim also mentioned gusts of 220 km/h in the 'Canterbury High Country', which I assume is from Mt Hutt?.

Meanwhile across the Strait, I see CentrePort (Ports of Wgtn) reported gusts to 157 km/h (just 4 km/h shy of Mt Kaukau), along with 139 km/h gusts at Kelburn and 141 km/h at the Rimutaka Summit (although The Press quotes MS as saying 170 km/h at Rimutaka Summit and Mt Kaukau?).

wind gone northerly here (so much lighter)
but might go back NNW as the front gets closer, as the NNW wind is ramping up over the far north now
as the low on the front deepens more

The breakfast show interviewed the Mayor or welly this morning ...she mentioned about is climate change making gales more commen in welly....when in fact the trend has been the other way around...but this spring is more like back to "normal"

there is good N gales moving down the eastern side of northland now...the Hauraki plains will be getting those

I suspect I will cop it here as the front goes through

I like the way that narrow band of rain on the frontal edge is developing off the west coast of the north island. I tend to think it will slide south of Hamilton though. But looks like it will have sever gales associated with it.

NNW wind ramping up here...huge gusts coming through
I would not be suprised if I get 60 kts soon
as I can see alot of wind on the water out on ocean

and the barometer is still dropping fast..this low is deepening alot at the moment

update: gusting to 51 kts here now and sand pouring down the coastline...things are going to get severe here soon

gusting to 58 kts here now...

Moisture is a problem in the set-up for the South Island today. Here is a GFS Skew-T chart for the South Canterbury area, notice the shear. However the SFC moisture is very dry.
It may lead to development further up in the atmosphere..... But I doubt convection would be at the SFC.

Hail is still in the picture due to the very cold upper air. I dont think this setup will pan out like a Summer convective event but I do think you will get Lightning activity in any CB's that develop due to the good lapse rates.