Deep Subtropical Low - Sept 24-26

[jamie]

I'm on my ipad ATM so can't post a picture of the Gfs forecast for 1 week out. Always exciting to see things like that but I'm not holding my breath for it to eventuate. I won't be in the country anyway actually.

[Tornado Tim]

I'm on my ipad ATM so can't post a picture of the Gfs forecast for 1 week out. Always exciting to see things like that but I'm not holding my breath for it to eventuate. I won't be in the country anyway actually.

If your meaning Wednesday, yes it looks very good. But we have quite a few days before we can get properly excited, LOL

[jamie]

the only reason i mentioned it is that the BOM (even better) and ECMWF (much weaker) models have it too.

[shovelopikis]

What exactly is this weather event Wednesday? Can't access gfs on phone.

[jamie]

very deep low from the north. dont even worry about it for at least another 4 days. Chances are it will not be there on the next runs anyway.

[spwill]

Yes, a decent looking low system in the modelling for next week, the North Island looks in the firing line but yes, it is still very early days with this system. I will be away on the Sunshine Coast, Qld next week hopefully in sunshine.

[Tornado Tim]

If the forecast pan's out, it will be very interesting, as you dont see many tropic based low's migrating south this early. We aren't even in Summer yet!....

I will be away on the Sunshine Coast, Qld next week hopefully in sunshine.

Rub it in why dont ya, LOL

[Manukau heads obs]

we have school kids on camp at whangaporoa next week...wont be very good for them...dang

[CWUweather]

I know it is a long way out but models are showing the first sub-tropical low for a while moving down over the north island! This could bring heavy rain and gales for the upper half of the north island! Metservice already has it featuring in their Severe Weather Outlook and WeatherWatch.co.nz already mentioning it!
What are thoughts on this?

[NZstorm]

Rainfall/flooding looks to be the primary severe weather risk with that subtropical low modeled for next week. Places exposed to E/SE such as Northland and Gisborne stand to get a good soaking. The ground is already saturated so there will be good run off. Its early for details though.

[Manukau heads obs]

beause this event has been raised early, then I have been able to inform the camp teacher for a school camp next week at whangaparoa....about the fact that a trip to tiritiri island on wedensday might not be able to go ahead...and if the day that occurs could be changed...
i.e having lots of advanced warning can help...
its still looking likely that wedensday is not going to be good for taking a ferry to tiritiri (it is a quick cat though fullers...I wonder at what point it would be cancelled...an east or SE wind in the gulf is a fair bit of fetch...

ps, its the jet stream sitting way up over new caledonia that looks like the driver for this low

[NZstorm]

GFS chart here Brian of the polar jet pattern on Wednesday. The polar jet unusually far north!

[jamie]

Now this is unlocked could a mod move over all the previous posts about this event. Thanks

[Nev]

Now this is unlocked could a mod move over all the previous posts about this event. Thanks

Done!

[CWUweather]

I created a thread for this but it got locked!!

[David]

Metservice have moderate/high confidence of heavy rain and gales across much of the North Island, and also heavy rain in the NE of the South Island

metservice_severe_outlook_210913.png

http://www.metservice.com/national/warn ... er-outlook
Issued: 2:31pm Saturday 21 Sep 2013
Valid from Monday 23 September 2013 to Thursday 26 September 2013

A narrow ridge of high pressure is expected to spread onto the country on Monday, then become slow moving over the lower South Island on Tuesday and Wednesday.

A deep subtropical low is expected to approach the far north of the North Island late Tuesday, then move southeast past the upper North Island and away to the east of the North Island on Thursday. The low is forecast to spread rain and strong easterlies over northern and central New Zealand on Tuesday and Wednesday, then the flow turns southerly over the entire country on Thursday as the low oves away to the east and a ridge of high pressure pushes into the Tasman Sea.

There is high confidence that heavy rain and severe gale easterlies will affect Northland, Auckland, Coromandel Peninsula, western Bay of Plenty and Gisborne on Tuesday and Wednesday. On Wednesday, there is also high risk of heavy rain for Hawkes Bay, Wairarapa, Wellington, Marlborough and northern Canterbury, while on Thursday there is moderate confidence of heavy rain in the east from Hawkes Bay to Marlborough, including Wellington.

In addition, there is moderate confidence of severe gale east to southeasterlies during Wednesday and early Thursday for the North Island west of the main ranges from eastern Bay of Plenty and Waikato southwards, and for the Marlborough Sounds.

[Manukau heads obs]

at this rate our schools trip to Tiritiri island on wedensday looks very doubtfull

[David]

at this rate our schools trip to Tiritiri island on wedensday looks very doubtfull

I hope your school will reschedule to do the trip at a later date rather than completely cancel. I went there on a school trip around 10 years ago and it really is an enjoyable day trip!

[Richard]

With many of the models showing no rain at all for the NE of the SI I'm wondering why the MS have a high risk

[NZ Thunderstorm Soc]

With many of the models showing no rain at all for the NE of the SI I'm wondering why the MS have a high risk

Just incase, there, Richard boy

[Richard]

With many of the models showing no rain at all for the NE of the SI I'm wondering why the MS have a high risk

Just incase, there, Richard boy

But just incase should be more a low to mod risk given the models are not consistent at this stage.

[NZstorm]

European and Ukmet both have low crossing top of Northland and then moving SE.

European for midnight Tuesday.

[Richard]

Looking to be coming down more to the west than it was forcasted to a day or so ago.

[David]

European and Ukmet both have low crossing top of Northland and then moving SE.

European for midnight Tuesday.

Only 2 days out now and GFS still wants to drag it down further east. UKMO and ECMWF are in pretty good agreement though.

[David]

Updated severe weather outlook is largely unchanged:

metservice_severe_outlook_220913.png

http://www.metservice.com/national/warn ... er-outlook
Issued: 1:58pm Sunday 22 Sep 2013
Valid from Tuesday 24 September 2013 to Friday 27 September 2013

A deep subtropical low is expected to approach the North Island during Tuesday and should lie near Cape Reinga by midnight Tuesday, with a strengthening easterly flow and rain spreading across the North Island and upper South Island during Tuesday and Wednesday. The low should move southeast during Wednesday and Thursday, towards the Chatham Islands, with the flow over New Zealand turning southwest.

There is high confidence that heavy rain and severe gale easterlies will affect Northland, Auckland, Coromandel Peninsula, western Bay of Plenty and Gisborne on Tuesday and Wednesday. Rain should gradually spread south later Tuesday and on Wednesday, with a moderate confidence of heavy rain in Hawkes Bay late Tuesday and on Wednesday, then in Wairarapa and Wellington on Wednesday. Further south, there is a high confidence of rain reaching warning criteria in Marlborough and northern Canterbury on Wednesday.

In addition, there is moderate confidence of severe gale east to southeasterlies during Tuesday and Wednesday for the North Island west of the main ranges from eastern Bay of Plenty and Waikato to Wellington, and also for the Marlborough Sounds.