Strong, Cold Southwest Flow over NZ - 18th-20th July

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Michael
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Strong, Cold Southwest Flow over NZ - 18th-20th July

Unread post by Michael »

Metservice on their rain chart has a "Bomb" goes from 992hpa on Friday to 950hpa on Saturday 24hrs later as it crosses the south island lying to the SE of Canterbury sat 12pm.

Mod edit: Title edit due to change in scenario
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Re: Even Deeper low Fri sat 17th 18th July

Unread post by Storm Struck »

Abit early days but one to watch if it continues to follow simular predictions through out the week coming, 961hpa off BP thats crazy :lol: .
Anyway we shall see, its about time the SI got one these big buggers :-) .
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Re: Even Deeper low Fri sat 17th 18th July

Unread post by gllitz »

HOLY CRAP!! :eek: ....is all I have to say...but NO DOUBT it will change...more than likely fizzle, dare I say it...but worth keeping an eye on.
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Re: Even Deeper low Fri sat 17th 18th July

Unread post by CHCH Weather Chaser »

Yes, looks very extreme and scary at the moment! Im sure it will change, it can only weaken you would think! Looks very messy in the near waters for the next week or so
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Re: Even Deeper low Fri sat 17th 18th July

Unread post by Myself »

I wouldn't worry. ECMWF has it off to the east (forecast charts are 6 hours out but it's enough to give an impression, and 6 hours is meaningless at this range anyway) and looking less scary.
Don't "hang your hat" on the GFS this time (as usual). If it turns out right though, post your hats to me and I'll eat them.

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Re: Even Deeper low Fri sat 17th 18th July

Unread post by NZstorm »

Todays 00Z gfs run for next Friday is a heavy snow set up for inland South Island. Would be interesting if that could come off. 12 June 2006 all over again. But 6 days away, the modeling is liable to change.
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Re: Even Deeper low Fri sat 17th 18th July

Unread post by Dale »

Anything beyond 48 is pushing it, no matter the model.. 168 is simply insane but provides 1 of 2 things.. an eat your hat scenario, or a lot of laughs & 2 pages of chitter before it fizzles into a puff of smoke. Lets start looking at LWT's.. or lack of them.
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Re: Even Deeper low Fri sat 17th 18th July

Unread post by Myself »

Dale Small wrote:Anything beyond 48 is pushing it, no matter the model
Might have been true 10-20 years ago but is no longer that case. Models are often pretty damn good out to 120.
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Re: Even Deeper low Fri sat 17th 18th July

Unread post by gllitz »

Latest ECMWF seems to show a bit of nastiness around from the +120-192 hr mark...will be interesting to watch how the runs go for the next couple of days. Would be nice if the model had smaller chunks and was broken down further...like 3 or 6 hourly, for example...or maybe this is already available and I am not looking in the right place?
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Re: Even Deeper low Fri sat 17th 18th July

Unread post by southerly-hunter »

They've weakened again by the look of the newest map predictions, further north again and just clipping canterbury. Still early though, I'm best to start wishing against it i'd say knowing my luck if i start hoping for it venturing further south it'll take a savage swing and bail for fiji!
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Re: Even Deeper low Fri sat 17th 18th July

Unread post by spwill »

ECMWF has it off to the east (forecast charts are 6 hours out but it's enough to give an impression, and 6 hours is meaningless at this range anyway) and looking less scary.
ECMWF has followed GFS with the general idea of a deep low forming near NZ, off to the east.
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Re: Even Deeper low Fri sat 17th 18th July

Unread post by Storm Struck »

Interesting set up this weekend as i mentioned earlier, a slow moving low crosses central NZ on Friday around 995hpa with scatterd rain about the top half of the South Island.
This continues into Saturday morning and if it manages to connect up with the cold blast coming up from the south then things could get interesting.
But still it does look alot better now for Overnight Saturday and into early Sunday for some very low level snow if not near sea level for Canterbury at this stage.
The high now sits further west over Australia meaning a wider and much better S-SW flow can be established not just in Otago and Southland but as i say in Canterbury, Marlborough as well.
But the darn models can and will change we shall see :crazy: _b .
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Re: Even Deeper low Fri sat 17th 18th July

Unread post by southerly-hunter »

Latest charts i've seen have gone slightly more intense again, with a decent burst sat morning, but nothing like that map the charts released on sunday, which looked very intense with a deep low hanging off banks peninsula, now it's looking much more like a couple of days of soutwest showery weather, mainly in otago and southland i would think but we'll see, hoping there's more moisture in it than they're curently expecting too.
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Re: Even Deeper low Fri sat 17th 18th July

Unread post by Storm Struck »

Yes and then a more westerly pattern for early next week which will bring temperatures into the mild teens in some areas, before another cold snap by that weekend 25th July etc.
So certainly a busy time ahead.
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Re: Even Deeper low Fri sat 17th 18th July

Unread post by NZstorm »

Looking like a cold blast across much of NZ Sunday. Both GFS and UKmet point to this. Looking like Southland, south Otago and Dunedin will get some snow to sea level and some weaker showery activity spreading north with snow to 200m or lower on Banks Peninsula. Colder air spreads over North Island early Monday but without much precip.
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Re: Even Deeper low Fri sat 17th 18th July

Unread post by CHCH Weather Chaser »

I think it may be the warmest it has been in weeks out there. Its 9 degrees but feels mild! Had half an hour or steady light rain with big drops though earlier. Still very overcast, but light northerly airstream allowing soem mildness to be felt. Metservice going for Snow to sea level in Otago, Southland which i agree with. However, to 500m in Canterbury, i cannot understand that! Here they were saying to 200m when clearly it was not going to get below 600m Wednesday and now they go for 500m when any precipitation that does fall will see snow to 200m at the highest I would have thought with thickness of 520. Yes, we do not have the precipitation, yes it is hardly anything exciting to look forward to and no snow will accumulate but any precipitation that makes it to the coast will fall to lower than 500m I would have thought. If im wrong ill eat my hat! :lol:

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Re: Even Deeper low Fri sat 17th 18th July

Unread post by Razor »

It will be for the most part largely a fine sunny weekend for ChCh.
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Re: Even Deeper low Fri sat 17th 18th July

Unread post by rawdon »

Its been a very pleasant day here in the Upper Valley of the Hutt .. peaked 14.6c a short time ago ..The warmest for quite some time. And sunny to boot ... Rule of thumb going back many years tells that when the temps reach 16c (61F as it was back then ) over several days ..SPRING has arrived ..We can only live in hope.

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Re: Even Deeper low Fri sat 17th 18th July

Unread post by Shepherds Valley WX »

Gday Steve - I'm a fellow Upper Hutt resident. Could'nt agree more with you re the winter weather, it seems like it has been overcast, gloomy and raining for months in the Hutt now! We have already gone through a full cord of firewood as I am sure it has also been colder than normal as well. Must compare WX Station data from the last few years to confirm that though...
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Re: Even Deeper low Fri sat 17th 18th July

Unread post by Storm Struck »

I am thinking the same as Mark and wondering just why 500m for the snow when the models indicate very low level snow.
To me the change comes through around 8pm Saturday night with heavy squally showers, and i am picking the snow level to 400m at first then dropping to 200m by around 10pm so it will be a sharp drop.
However if there is any convective heavy type CB showers then i think the snow may reach near sea level at times, as the MS forecast the chance of TS down south some of these might come up.
Although they will probly be low topped because of strong wind shear.
Sunday most likly more a Banks Peninnsula event with fine weather elsewhere and cold strong blustery SW winds, maybe the odd shower belting through the city late afternoon for awhile.
Then the frosts come for Sunday/Monday nights, before a westerly flow becomes established over the South Island.

Ok nobody point thier fingers :-$ but looks to be another low system near the end of next week i say no more :-# .
Dont blame me if it fails i didnt curse it =; .
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Re: Even Deeper low Fri sat 17th 18th July

Unread post by RWood »

Shepherds Valley WX wrote:Gday Steve - I'm a fellow Upper Hutt resident. Could'nt agree more with you re the winter weather, it seems like it has been overcast, gloomy and raining for months in the Hutt now! We have already gone through a full cord of firewood as I am sure it has also been colder than normal as well. Must compare WX Station data from the last few years to confirm that though...
Here's something I've already posted in a few other spots. Personally I loathe the kind of weather described (persistently dull) more than any other. In terms of cloudiness it's about equivalent to a London December, or actually a little worse relatively speaking, as their available daylight is less than ours.

Record low sunshine at Kelburn
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In the 3 weeks 25 June - 15 July, Wellington managed just 23.9 hours of sunshine, this being less than 1/3 of the average daily rate for this time of the year. 9 days had no sun, and 4 others had less than 1 hour.. The highest total was 5.6 hours on July 3.

This total is 4 hours lower than the previous mark set during June 1978, a significant margin. Daily records (or rather those currently available on NIWA's CliFlo) go back to 1954.

Such a spell would be fairly uninspiring in any circumstances, but coupled with a long period of unusual coldness, it is adding insult to injury! Rainfall was not high during the period or the previous weeks of June, but a general lack of warmer drying winds has left everything looking very damp.


The slight promise of some brighter days ahead may at least prevent the 4-week record being broken as well.
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Re: Strong, Cold Southwest Flow over NZ - 18th-20th July

Unread post by spwill »

Personally I loathe the kind of weather described (persistently dull) more than any other.
I think the cold makes dull weather much worse.
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Re: Strong, Cold Southwest Flow over NZ - 18th-20th July

Unread post by Manukau heads obs »

this low has taken a while to take shape, but it looks like its starting to deepen quickly now
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Re: Strong, Cold Southwest Flow over NZ - 18th-20th July

Unread post by GraemeWi »

Cool - thunder in West Auckland
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Re: Strong, Cold Southwest Flow over NZ - 18th-20th July

Unread post by ricky »

Pretty sure I just saw the sky lit by a flash of lightning and heard some thunder, though the detector didn't show up anything.
Looks like that low centre is quite close NW of Auckland going by the rain radar
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