Major Low Pressure system - 8th to 12th May

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Manukau heads obs
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Re: Major Low Pressure system - 8th to 12th May

Unread post by Manukau heads obs »

also note the isobar spacing
i.e gfs is small spacing (steps between)
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Re: Major Low Pressure system - 8th to 12th May

Unread post by NZstorm »

Remember that MetVuw is exclusively GFS. So the worst model of the lot.

I don't think the gfs is any worse than any other model. UKmet and ECMRF are not any better. And GFS is more comprehensive in its forecast period and output.
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Re: Major Low Pressure system - 8th to 12th May

Unread post by Vertigo »

its a best guess forecast based on its internal algorithms, which become less accurate the further out you look, like all models. its debatable whether its more innaccurate than other models, but i think they all get it wrong sometimes. not to say dont use them as a reference - just expect things to change a bit.

that said, its a good looking system from the model runs. stormy weather ahead indeed.
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Re: Major Low Pressure system - 8th to 12th May

Unread post by spwill »

I was looking at the isobars and thinking how windy it was going to get but metservice hadnt got anything about that. You learn something new everyday
http://www.metservice.co.nz/public/mari ... ipara.html
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Re: Major Low Pressure system - 8th to 12th May

Unread post by Manukau heads obs »

i see the marine forecast now reports 5m swell
I thought it looked way bigger than 4m swell
I reckon it was 6m at one stage yesterday (around lunch time)
the coast was a real mess!
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Re: Major Low Pressure system - 8th to 12th May

Unread post by Razor »

Metservice now saying for ChCh on monday....fine weather with NE.
Its all over the place.
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Re: Major Low Pressure system - 8th to 12th May

Unread post by Michael »

Ecmwf often changes almost the opposite each day until about 3 days out then its more accurate.
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Re: Major Low Pressure system - 8th to 12th May

Unread post by CHCH Weather Chaser »

Razor wrote:Metservice now saying for ChCh on monday....fine weather with NE.
Its all over the place.
Razor ive noticed over the past few weeks that before 1030-11am when they update their brief forecasts and make alterations to the 5 day forecast the 5th day (in this case monday) is always the same symbol and forecast as the current day. The temp seems to be different but the symbol and description is always the same, it must be a setting they have. So dont read anything into that.

Latest models seem to show this as a bit of a fizzer for Christchurch now :(
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Re: Major Low Pressure system - 8th to 12th May

Unread post by Manukau heads obs »

still good instability around
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Re: Major Low Pressure system - 8th to 12th May

Unread post by Razor »

MarkThomas wrote:
Razor wrote:Metservice now saying for ChCh on monday....fine weather with NE.
Its all over the place.
Razor ive noticed over the past few weeks that before 1030-11am when they update their brief forecasts and make alterations to the 5 day forecast the 5th day (in this case monday) is always the same symbol and forecast as the current day. The temp seems to be different but the symbol and description is always the same, it must be a setting they have. So dont read anything into that.

Latest models seem to show this as a bit of a fizzer for Christchurch now :(
If thats true its a bit of a shocker.
They still show fine and NE for monday
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Re: Major Low Pressure system - 8th to 12th May

Unread post by spwill »

Classic looking Cb tops around Auckland today, some lightning strikes just west of Auckland /Northland over the warm sea.
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Re: Major Low Pressure system - 8th to 12th May

Unread post by Manukau heads obs »

Thunder heard :)
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Re: Major Low Pressure system - 8th to 12th May

Unread post by waterboy »

No one down south seems very worried about thiese forcasts. Is it crying wolf thing? It seems strange to me since we are now moving into the part of the year where the nz weather all seems to happen in the south island but this yyear no one seems to be planning for it the way we normally do.
Maybe we will all be caught out on the hop?
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Re: Major Low Pressure system - 8th to 12th May

Unread post by Lawrence »

I think I`m going to stick to Monday for this system,snow down to 200m,possibly sleet for lower parts of Canterbury :|
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Re: Major Low Pressure system - 8th to 12th May

Unread post by Brassnz »

I'm on Waiheke Island today for work - hard life! Nice calm ferry crossing from Half Moon Bay at 7am this morning, and some fairly spectacular formations popping up out Akld way now.
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Re: Major Low Pressure system - 8th to 12th May

Unread post by Razor »

Karshvardidgâh wrote:I think I`m going to stick to Monday for this system,snow down to 200m,possibly sleet for lower parts of Canterbury :|
You couldn't be further away from what the Metservice are saying so far today then!
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Re: Major Low Pressure system - 8th to 12th May

Unread post by Razor »

haha...MarkThomas is vindicated, the MS have flip flopped Monday now cold and showery!
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Re: Major Low Pressure system - 8th to 12th May

Unread post by Lawrence »

Razor wrote: You couldn't be further away from what the Metservice are saying so far today then!
Not sure they are looking at the whole picture,SLT etc.and the way the system is moving.Some times its better to throw away the model and look at whats happening further away instead. ;)
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Re: Major Low Pressure system - 8th to 12th May

Unread post by DT-NZ »

Manukau heads observer wrote:Thunder heard :)
_b nice... pic... had a couple of those clouds pass over a few minutes ago... with some heavy squally rain... now, the sun's out.... hmm..... take care.
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Re: Major Low Pressure system - 8th to 12th May

Unread post by Vertigo »

great looking instability today! i happened to lock my keys in the house, so i was treated to a delightful walk to work amongst the Cb's. the overcast seems to be creeping in now.
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Re: Major Low Pressure system - 8th to 12th May

Unread post by CHCH Weather Chaser »

Razor wrote:haha...MarkThomas is vindicated, the MS have flip flopped Monday now cold and showery!
;) It happens for every city before 1030am or sometimes a little later until they update their more extended forecast. Its something they need to change. Should say "N/A" until they update.
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Re: Major Low Pressure system - 8th to 12th May

Unread post by Tornado Tim »

Yes I can see the nice Mature thunderhead all the way from Matangi,
Here it is: Look in the Background, the anvil is quite defined.
Nice example of CB incus, I wish I was closer.
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Re: Major Low Pressure system - 8th to 12th May

Unread post by Storm Struck »

Nice to see blue dome skies after what we had yesterday, and there's a good coating of snow along the Southern Alps too.
Yes this low system has become more a later on event for Canterbury now, more a Sunday,Monday,Tuesday event.
Snow levels look to get reasonable low around 200-300m along with heavier rain for Tuesday, so definatly some intermixed sleet and hail maybe some of the hill suburbs around the Port Hills might see some flakes Tuesday night.
Tonights SW change might bring in the chance of a thunderstorm i am thinking, if going by Tuesday nights front which was abit weaker than this cold front and managed to form some CB's offshore.
I just realised also its a Full Moon this weekend so the tides will be higher, which means all that surface water has to go somewhere and depending on how much falls could cause some problems.
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Re: Major Low Pressure system - 8th to 12th May

Unread post by Philip Duncan »

Vertigo wrote:great looking instability today! i happened to lock my keys in the house, so i was treated to a delightful walk to work amongst the Cb's. the overcast seems to be creeping in now.
How are you going to get back inside after work!?
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Re: Major Low Pressure system - 8th to 12th May

Unread post by Tornado Tim »

Another lot have blown through the Cap.
They may move south as I am getting a NW wind.
Update 2.51 PM: About 3 CB's have blown up in the Waikato, 1 to West, 1 to the SSW, and one to the SE of me.
Here some pics.
I really cant figure out why met service didn't even put a thunderstorm risk for the waikato today?
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Last edited by Tornado Tim on Thu 07/05/2009 14:51, edited 1 time in total.
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