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Complex low Oct 1 & 2
Posted: Fri 29/09/2017 15:12
by Cyclone Tracy
This is lining up to a very windy direct hit to the top half of the North Island. A surface low will spawn and deepen from a polar trough early Sunday morning. The finer details will be a little clearer in the next 24 hours but its certainly an unstable cold shot from the Antarctic as the surface temperature leak is currently underway.
Re: Complex low Oct 1 & 2
Posted: Fri 29/09/2017 17:55
by TonyT
There is no "unstable cold shot from the Antarctic" feeding this system. Its a wave in the westerly flow. The air in the system originated south of Australia, well north of sub Antarctic waters.
127156_trj001.gif
Re: Complex low Oct 1 & 2
Posted: Fri 29/09/2017 19:10
by Cyclone Tracy
TonyT wrote: ↑Fri 29/09/2017 17:55
There is no "unstable cold shot from the Antarctic" feeding this system. Its a wave in the westerly flow. The air in the system originated south of Australia, well north of sub Antarctic waters.127156_trj001.gif
Hi Tony, nice input but the latest EC & GFS runs don’t entirely agree with you. They think there is a polar air injection into the base of the trough from around 65 to 70 degrees south. If they are right, it looks like the convergence is spring cold shot to me, which would be a tad unstable and quite windy through the north island from the latest runs. I won’t be hanging out the washing on Sunday up here
Re: Complex low Oct 1 & 2
Posted: Sat 30/09/2017 08:14
by NZstorm
Yes, tomorrows trough is a polar trough. Tony's output from the Hyspilt model is not measuring the set up well as the source selected is at the 500m level. The cold air advection is higher up in the atmosphere.
Looking like squally thunder on the cards for Sunday for the west of the North Island. Front coming in tomorrow morning after dawn.
Re: Complex low Oct 1 & 2
Posted: Sat 30/09/2017 13:42
by Cyclone Tracy
MetService now starting to crank up the outlook on the North Island. Gales and thunderstorms for Sunday into Monday.
Latest Access R (18z) shows the cold core gyre drop to around 979 hPa Sunday morning off the west coast of the south Island and then develop a 2nd core around the south Taranaki bight Sunday night. It's going to have a nice wrap around south westerly attack late Sunday into Auckland.
Re: Complex low Oct 1 & 2
Posted: Sat 30/09/2017 20:37
by NZ Thunderstorm Soc
Cyclone Tracy wrote: ↑Sat 30/09/2017 13:42
MetService now starting to crank up the outlook on the North Island. Gales and thunderstorms for Sunday into Monday.
Yes, well I wish they wouldn't go to bloody Auckland all the time, and come down this way instead
Re: Complex low Oct 1 & 2
Posted: Sun 01/10/2017 10:12
by spwill
The better upper level cooling moving in this afternoon, best chance to hear thunder looks like later in the day in the west.
Re: Complex low Oct 1 & 2
Posted: Sun 01/10/2017 10:46
by Cyclone Tracy
spwill wrote: ↑Sun 01/10/2017 10:12
The better upper level cooling moving in this afternoon, best chance to hear thunder looks like later in the day in the west.
Spot on - Latest GFS 3 hour snap shot showing around -29 to -30c @500 hPa west of the North Island. Sustained winds over 100 km/h @850 hPa, it's going to get a little breezy and unstable.
Re: Complex low Oct 1 & 2
Posted: Sun 01/10/2017 11:32
by David
Feeling more like July here today rather than October. 12C with rain most of the morning. Was quite heavy between 9 and 10am.
Re: Complex low Oct 1 & 2
Posted: Sun 01/10/2017 15:14
by Cyclone Tracy
10mm so far here. Baro currently 993 hPa and highest wind gust so far of 52km/h
Re: Complex low Oct 1 & 2
Posted: Sun 01/10/2017 15:32
by RODALCO
Vector has issued a storm warning for us field staff when we are called out to attend faults.
Do it safe and don't take any risks out there. Main risk is tonight and tomorrow morning at this stage.
Re: Complex low Oct 1 & 2
Posted: Sun 01/10/2017 16:02
by GraemeWi
Just had a very sharp squall hit here is Swanson with very strong wind and hail
Re: Complex low Oct 1 & 2
Posted: Sun 01/10/2017 18:16
by NZstorm
GFS has the wind threat aimed at Northland and North Auckland overnight.
Re: Complex low Oct 1 & 2
Posted: Sun 01/10/2017 19:48
by Cyclone Tracy
Gusting to around 70 km/h here with hail in that last squall. Some private stations on the north shore are 80 km/h to 90 km/h now with the latest batch of squalls coming through.
Re: Complex low Oct 1 & 2
Posted: Mon 02/10/2017 03:15
by Simon Culling
Looks like it was a bit windy at the NZ Women's Open Golf Tournament at the aptly named Windross Farm golf course on Sunday afternoon:
http://www.bbc.co.uk/sport/golf/41460869
I believe the course is a little inland from Auckland.
Re: Complex low Oct 1 & 2
Posted: Mon 02/10/2017 06:29
by NZstorm
Quite a decent system on the charts but the max gust at the airport was only 40 knots. But I reckon Northland must have got some decent gusts this morning.
There was a couple of flashes and distant thunder about 3.30am here.
Re: Complex low Oct 1 & 2
Posted: Mon 02/10/2017 07:27
by Cyclone Tracy
18mm, top gust of 88 km/h, hail, thunder during the night.
I see a private weather station west of Whangarei was gusting over 120 km/h during the night.
A few inches of snow in central north island overnight.
Re: Complex low Oct 1 & 2
Posted: Mon 02/10/2017 08:22
by David
Max gusts only 52 km/h here, nothing particularly unusual. 29mm rain since early yesterday.
Re: Complex low Oct 1 & 2
Posted: Mon 02/10/2017 08:34
by spwill
I was expecting more in the way of wind and thunder from this system, no strong winds at my place.
Re: Complex low Oct 1 & 2
Posted: Tue 03/10/2017 07:30
by Nev
Re the LPGA golf tournament video at Windross Farm, Ardmore Aero right next door recorded gusts to 65 km/h on Sunday afternoon (and up to 78 km/h yesterday), although it looked more squally at Ground Zero. Media reports also say gusts were close to 100 km/h on the Harbour Bridge and around 110 km/h in the Hauraki Gulf. While further south, Aurora Energy said gusts of more than 100 km/h caused outages to 900 Otago Peninsula customers yesterday.
Here's some of the higher gusts MS recorded over the last 2 days…
Code: Select all
Oct 1-2 Gusts km/h
Cape Reinga 135
Manukau Heads 125
Golden Valley 109
Mamaku Radar 109
Hokianga 107
Stratford Mount 106
Kaikohe 104
Okahu Island 104
Nugget Point 104
Mokohinau Islands 102
Whangaparaoa 94
Invercargill Aero 93
Takapau Plains 91
Tutukaka Harbour 89
Auckland Aero 89
Dunedin Aero 89
Whenuapai 87
Port Taharoa 85
Hicks Bay 85
Mahia 83
Le Bons Bay 83
Re: Complex low Oct 1 & 2
Posted: Tue 03/10/2017 08:59
by GraemeWi
I checked my weather station last night to see what the peak gust was for us, 91kph just after midnight / early am Monday morning.
Plenty of tree debris on the roads too
Re: Complex low Oct 1 & 2
Posted: Tue 03/10/2017 13:07
by Cyclone Tracy
A few trees down around here yesterday as well.
Nice stats Nev. 100 km/h on the Harbour bridge lines up pretty close to my 88 km/h not far from there.