Unstable squally western NZ 11-15th July

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NZstorm
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Unstable squally western NZ 11-15th July

Unread post by NZstorm »

A cold front crosses the North Island today with possible squally thunderstorms/hail in the west. The front will be over Taranaki around the middle of the day and Auckland around mid evening. The instability on the front looks very marginal so we'll have to see what develops with it today. Its not as unstable as what we had Saturday night. Need a bit more moisture to come in from the North Tasman!

A very cold polar airmass will cross the North Island overnight with squally showers/hail and some thunder in the west.

H500mb chart below for midnight.
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Re: Unstable squally western NZ 11-12th July

Unread post by Tornado Tim »

Quite a few thunderstorm Warnings for the lower north island overnight.

The one that current now (8.20 AM) mentions the risk of a tornado dropping from this storm.
77ba-131158716c0-36ee80-13115921340-1.0.png
SEVERE THUNDERSTORM WARNING
TOP PRIORITY FOR IMMEDIATE BROADCAST
Issued by MetService at 07:42 am Monday 11 July 2011.
Valid until 08:30 am Monday 11 July 2011.
This warning affects people in the following local government areas:
HOROWHENUA, PALMERSTON NORTH CITY, MANAWATU and RANGITIKEI.
At 07:30 am, MetService weather radar detected severe thunderstorms near OFFSHORE MANAWATU, OFFSHORE WANGANUI and OFFSHORE NORTH OF THE MARLBOROUGH SOUNDS.
These severe thunderstorms are moving towards the east, and are expected to lie near OFFSHORE MANAWATU at 08:00 am and near PALMERSTON NORTH, FOXTON, FEILDING, TOKOMARU, RONGOTEA, SANSON and HIMATANGI at 08:30 am.
These thunderstorms are expected to be accompanied by very heavy rain, large hail, damaging wind gusts and possible tornadoes.
Very heavy rain can cause surface and/or flash flooding about streams, gullies and urban areas, and make driving conditions extremely hazardous.
Large hail can cause significant damage to crops, orchards, vines, glasshouses and vehicles, and make driving conditions hazardous.
Very strong wind gusts can break branches from trees, damage roofing, and make driving hazardous especially for high-sided vehicles and motorcycles.
Tornadoes can blow out windows, lift roofs, break large branches off trees, generate dangerous flying debris and blow vehicles off the road.
A Severe Thunderstorm Watch remains in force for BULLER, CANTERBURY HIGH COUNTRY, KAPITI-HOROWHENUA, MANAWATU, NELSON, TAIHAPE, TARANAKI, TARARUA, WAIRARAPA, WANGANUI and WELLINGTON.
The Ministry of Civil Defence and Emergency Management advises that as storms approach you should:
- Take shelter, preferably indoors away from windows;
- Avoid sheltering under trees, if outside;
- Move cars under cover or away from trees;
- Secure any loose objects around your property;
- Check that drains and gutters are clear;
- Be ready to slow down or stop, if driving.
During and after the storm, you should also:
- Beware of fallen trees and power lines;
- Avoid streams and drains as you may be swept away in flash flooding.
This warning is due to be updated or lifted by 08:30 am Monday 11 July 2011.
Looking forward to the squalls and thunder tonight.
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Re: Unstable squally western NZ 11-12th July

Unread post by David »

A fine sunny start here, only 1mm overnight. Although it's winter, the sunny conditions should provide a little surface heating I would hope! :smile:
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Re: Unstable squally western NZ 11-12th July

Unread post by jamie »

Thunder here just now
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Re: Unstable squally western NZ 11-12th July

Unread post by NZstorm »

I agree David, the daytime heating will help the instability along a bit but the front may not come into Auckland till well after sunset. Currently 17C in Grey Lynn.
Nice looking cb out to west, just offshore, looks like a thunderstorm.
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Re: Unstable squally western NZ 11-12th July

Unread post by David »

NZstorm wrote: Nice looking cb out to west, just offshore, looks like a thunderstorm.
Can't see anything ominous heading for Auckland area, typical LOL. Partly cloudy here now after a sunny morning, light NNW breeze. Looks like that CB is going into Nth Waikato.

Really hope tonight delivers the thunder, as I see we have no risk tomorrow (according to MS)...
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Re: Unstable squally western NZ 11-12th July

Unread post by NZstorm »

Really hope tonight delivers the thunder, as I see we have no risk tomorrow (according to MS)...
I see the Met Service have got no thunderstorm risk for after midnight for Auckland/Waikato. But there will be a thunderstorm risk in the west from about Auckland south. midnight to 6am Tuesday. See 500mb chart above.
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Re: Unstable squally western NZ 11-12th July

Unread post by Tornado Tim »

Yup thunderstorms have already hit Waikato.

This line heading towards Otorohanga looks very beefy must have a good amount of Hail....
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Re: Unstable squally western NZ 11-12th July

Unread post by jamie »

So why no severe thunderstorm warning on it? It seems to me as if it would be severe.
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Re: Unstable squally western NZ 11-12th July

Unread post by Manukau heads obs »

I could see the tops from here as it went south of me
similar to the other CB's that have passed through that area yesterday

getting windy here now
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Re: Unstable squally western NZ 11-12th July

Unread post by David »

Heaps of lightning showing out to the west! :smile:

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Re: Unstable squally western NZ 11-12th July

Unread post by Tornado Tim »

Yup very strong echos being picked up by the Auckland radar, since its such a strong echo at a considerable distance be prepared for some wild weather coming up in 2-4 hours...

Nice thunderstorms too going by the satellite pictures.
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Re: Unstable squally western NZ 11-12th July

Unread post by Manukau heads obs »

yes, my boltec is picking up heaps of lighting on that CB MASS heading our way ...whooo!
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Re: Unstable squally western NZ 11-12th July

Unread post by NZstorm »

I can see the distant thunderheads out to W/SW from here. Should arrive in Auckland after sunset!
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Re: Unstable squally western NZ 11-12th July

Unread post by Vertigo »

if its anything like the other night, ill be very happy!
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Re: Unstable squally western NZ 11-12th July

Unread post by Manukau heads obs »

tracking an active cell to the west of kaipara...heading for the kaipara area,,...heads up!
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Re: Unstable squally western NZ 11-12th July

Unread post by Manukau heads obs »

actually that storm to the west of the kaipara area is moving ESE
towards auckland....
M/S should at least have a watch on it?
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Re: Unstable squally western NZ 11-12th July

Unread post by Philip Duncan »

Vertigo wrote:if its anything like the other night, ill be very happy!
I was in Chch on Sunday morning so missed it :-( Got an earthquake instead...but would prefer a good thunderstorm.
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Re: Unstable squally western NZ 11-12th July

Unread post by bmo »

Some dark clouds rolling in here, winds have increased a bit but not that much. Winds are around 38kph.
Hoping for some decent thunderstorms tonight!
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Re: Unstable squally western NZ 11-12th July

Unread post by David »

what makes the lightning detector plot strikes closer to Auckland than they really are? I notice a few strikes being plotted over West Auckland.
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Re: Unstable squally western NZ 11-12th July

Unread post by Manukau heads obs »

thats a good sign
means they are strong lightning bolts :)
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Re: Unstable squally western NZ 11-12th July

Unread post by Manukau heads obs »

the timing of this front is nice....just when it gets dark it will be here...hopefully it stays strong...
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Re: Unstable squally western NZ 11-12th July

Unread post by jamie »

blardy heck... its throwing out some strikes and they are strong too. my bolteck is plotting them very close to me but the are still over the ocean
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Re: Unstable squally western NZ 11-12th July

Unread post by bmo »

It's deteriorating really fast here very strong winds rolling in and getting darker by the minute.
Cant wait for this front to come and looking out to the harbour i would say we're going to be hit head on... \:D/
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Re: Unstable squally western NZ 11-12th July

Unread post by Tornado Tim »

Yup the boltek units are going nuts :D

Man I love this weather \:D/
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