General August Weather

[NZstorm]

Looking like a strong echo just to the north of Auckland now. 19mm here today.

[David]

A deluge in Howick now!

[Cyclone Tracy]

Water vapour continues to increase in the mid levels as the occluded front moves down the NI. Some fast big rainfall totals coming up in the central NI and BOP soon.

32mm and still ticking over here.

You have certainly been in the sweet spot a few times this year David

[spwill]

Heavy rain here currently but the radar shows the front is about to clear here. Looks like more heavy showers/isolated storms possible Friday.

[jamie]

Very stormy here. Very strong wind and sheets of heavy rain


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[David]

You have certainly been in the sweet spot a few times this year David

Yeah, interesting. It seems this is a good location to catch heavy downpours drifting south from the coastline (or just off the coast) of northern Auckland, which seems to be fairly common occurrence of late. Picked up 53mm for the day.

[Nev]

31mm here this morn, mostly between 5am-9am. Very strong winds peaked around 9am.
Sun's out now (edit: albeit briefly).

I see 21mm of Whangaparaoa's 40mm fell in the hour to 8am.

[David]

Pleasant 18.4C here this afternoon after the morning rain cleared, the warmest since 16th June.

[Cyclone Tracy]

Finished on 37mm here before the sun returned. Roughly double what models expected on the 12z run. They struggle with the impacts of cut off lows on a mesoscale level IMO.

Latest 00Z UKMet run showing the newly born cut off low from the subtropics much closer to the SI and NI eastern coastline on Friday, under a fujiwhara effect influence with the current Tasman low. One to watch over the next 72 hours for both North and South

[NZ Thunderstorm Soc]

I noticed that today's MS short forecast said a fine day for Canterbury, well the east coast of the SI.
South Canterbury/Timaru can't be in Canterbury anymore as it has been overcast all day with light rain especially this afternoon but has eased now. 7mm so far.
Still rather overcast and cloudy but it should clear this evening.

[Richard]

Well at least you are not lumbered in the High Country forecast area John

[Chris W]

Some beautiful cb forms visible from Kaikoura to the north early this evening. A rainy morning eased to a fine afternoon.

[NZ Thunderstorm Soc]

On 7 sharp, this evening, apparently there was an article about lightning.
Did anyone see it?

[Thunder081]

On 7 sharp, this evening, apparently there was an article about lightning.
Did anyone see it?

Yeah it was cool, I wonder if he's on this forum? Also anyone who didn't see it can watch it here: http://www.tvnz.co.nz/shows/seven-sharp ... ping-count

[Cyclone Tracy]

SSW event has stalled around the Tropopause. Tropospheric polar vortex is gaining incredible strength now, signs of weakening have stopped. Antarctic surface temperature anomaly now down to a level I've not seen before Looking like uncharted territory IMO....

More popcorn required

[Bradley]

Interesting that for Monday Metservice are now going for snow down to 300m asl for their rural Canterbury forecast for Darfield, seems a bit low based on both EC and GFS models at the moment?

[Cyclone Tracy]

Interesting that for Monday Metservice are now going for snow down to 300m asl for their rural Canterbury forecast for Darfield, seems a bit low based on both EC and GFS models at the moment?

There is a lot of uncertainty on where exactly the upper low will position itself which is having a flow on affect to where a potential surface cut off low will position itself on Tuesday morning. GFS just went rogue on the 18z run for parts of Canterbury for rainfall next week. No common agreement yet though.

[jamie]

Cyclone Tracy do you mind explaining what a cut off low is? And how this is different to a regular low?


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[Cyclone Tracy]

Cyclone Tracy do you mind explaining what a cut off low is? And how this is different to a regular low?


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Sure, its when a low-pressure system becomes disconnected from the westerly flow. Rapid deepening lows around the equinox is normally the peak time for these types of lows. That current Tasman low underwent deep intensification on Tuesday and cut off from the westerly belt Tuesday night, moving North West for 24 hours. Once they weaken, the ridge moves in and they move east again. These lows are much harder for models and Met agencies to predict once they disconnect from the westerly flow.

[jamie]

Thanks for that.

MetService have had another shocker forecast for here today. Forecast was for fine and 17 high. All we have had today is drizzle and rain totalling a measly 2mm but the drizzle and rain patches haven’t let up at all. I was looking forward to a fine day after the 35mm we had yesterday.


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[jamie]

Now over 10mm today with more to come from a day that was supposed to be fine. Zero sunshine hours and maxed out at 14 rather than 17.


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[Richard]

A range of 19 deg today from 0deg, nice spring feeling to the day

[David]

Now over 10mm today with more to come from a day that was supposed to be fine. Zero sunshine hours and maxed out at 14 rather than 17

Turned out quite dull and cloudy here too for much of the day, and felt quite cool with 15C max reached

[NZ Thunderstorm Soc]

A range of 19 deg today from 0deg, nice spring feeling to the day

Nice day here, as well. lovely, sitting in the sun talking to people.
Tomorrow, however, looks awful for here. gloom.

[cbm]

Now over 10mm today with more to come from a day that was supposed to be fine. Zero sunshine hours and maxed out at 14 rather than 17.


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Yeah, and the rain getting heavier now. Even with all the tools available these days still can get weather wrong less than 12hrs in advance. I know a few 10's of km error in position of a low makes all the difference but shows weather prediction is a task that has been nowhere near completely cracked yet.

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