Low for North Island Tues/Wednesday

Archive of NZ Weather & Climate
Forum rules
These topics are a read-only archive and may be subject to out-of-date information.

For today's weather discussion head to: New Zealand Weather & Climate
User avatar
NZstorm
Posts: 11333
Joined: Mon 10/03/2003 19:38
Location: Grey Lynn, Auckland
Has thanked: 342 times
Been thanked: 361 times

Low for North Island Tues/Wednesday

Unread post by NZstorm »

A small low is forecast to develop near New Caledonia today and will move quickly south and pass near East Cape early Wednesday. Looking like some rain for many northern and eastern regions of the North Island Tuesday/early Wednesday. The low doesn't look like much to get excited about though with no instability forecast apart from maybe in Gisborne. And the humid warm advection will pass east of the country. Forecast rainfall for Auckland is 20mm. According to GFS winds look like reaching gale force about exposed eastern areas from Northland to East Cape. The UKmet has the low passing just a bit further east with lass rain/wind for the NI. We will see what happens.
User avatar
Tornado Tim
Moderator
Posts: 4896
Joined: Sun 19/10/2008 17:17
Location: Raglan, Waikato / Hillcrest, Hamilton
Has thanked: 92 times
Been thanked: 178 times
Contact:

Re: Low for North Island Tues/Wednesday

Unread post by Tornado Tim »

NZStorm wrote:The low doesn't look like much to get excited about though with no instability forecast apart from maybe in Gisborne.
Funny that because i just got this and it says that Auckland has got some instability coming around on Tuesday at 1800 hours, However it does not look like much.
You do not have the required permissions to view the files attached to this post.
NZAPStrike.net - NZ Aus Pacific Strike Network
User avatar
Michael
Posts: 7210
Joined: Thu 27/03/2003 12:04
Location: Rainy Manurewa, Auckland - "City of Gales"
Has thanked: 0
Been thanked: 1 time
Contact:

Re: Low for North Island Tues/Wednesday

Unread post by Michael »

The map for Tuesday 1pm has the best prospect then Xmas day.....back to you know what.This was uploaded from the Metsercice rain tracker.
You do not have the required permissions to view the files attached to this post.
User avatar
NZstorm
Posts: 11333
Joined: Mon 10/03/2003 19:38
Location: Grey Lynn, Auckland
Has thanked: 342 times
Been thanked: 361 times

Re: Low for North Island Tues/Wednesday

Unread post by NZstorm »

Yes the 00Z GFS is now a bit more agressive with the moisture with 17-18C dps getting onto the North Island with possible destablisation Wednesday. Certainly seems to be a little bit of thunderstorm risk for us with this system now. But the UKmet keeps the very moist air just out to our east. For the instability it all comes down to those dewpoints, whether they come our way or not. No doubt we will see more changes in the details of this system in the coming model runs.
User avatar
Vertigo
Posts: 1181
Joined: Sun 09/12/2007 23:50
Location: Grafton, Auckland
Has thanked: 0
Been thanked: 7 times
Contact:

Re: Low for North Island Tues/Wednesday

Unread post by Vertigo »

looking very nice. will probably lose its convective activity before it gets here tho.
You do not have the required permissions to view the files attached to this post.
Collated weather maps @ http://ohthehugemanatee.com/weather/
User avatar
NZstorm
Posts: 11333
Joined: Mon 10/03/2003 19:38
Location: Grey Lynn, Auckland
Has thanked: 342 times
Been thanked: 361 times

Re: Low for North Island Tues/Wednesday

Unread post by NZstorm »

will probably lose its convective activity before it gets here tho.
Possibly, instability in this type of system can be fickle. GFS suggests the low will bring a bit of a thunderstorm risk into the north late Tuesday and this will spread south Wednesday. Afternoon heating Wednesday afternoon will favour further cb development over the west of the NI.

Chart here of modelled lifted index values for 12Z Tuesday (1am Wednesday). I have included 500mb winds which suggest good wind shear with this system.
You do not have the required permissions to view the files attached to this post.
Manukau heads obs
Posts: 12305
Joined: Mon 10/03/2003 16:30
Location: West Coast Road, Manukau Peninsula, North Island
Has thanked: 0
Been thanked: 0
Contact:

Re: Low for North Island Tues/Wednesday

Unread post by Manukau heads obs »

just back from being over in the coromandel over the weekend
bit of a heat shower over waiuku this aftenoon against the sea breeze :)
will be good to get the rain from this low from the north!
Last edited by Manukau heads obs on Mon 22/12/2008 20:37, edited 1 time in total.
Image
Brian Hamilton, weather enthusiast. My weather dataEmail: [email protected]
User avatar
Tornado Tim
Moderator
Posts: 4896
Joined: Sun 19/10/2008 17:17
Location: Raglan, Waikato / Hillcrest, Hamilton
Has thanked: 92 times
Been thanked: 178 times
Contact:

Re: Low for North Island Tues/Wednesday

Unread post by Tornado Tim »

Looking at the GFS tomorrow looks quite promising for Auckland to get thunderstorms.
DP:15
Cape is good and lifted index is good also with -2 to -3 values.
Hopefully it pans out for you guys up north from me.
You do not have the required permissions to view the files attached to this post.
NZAPStrike.net - NZ Aus Pacific Strike Network
User avatar
NZstorm
Posts: 11333
Joined: Mon 10/03/2003 19:38
Location: Grey Lynn, Auckland
Has thanked: 342 times
Been thanked: 361 times

Re: Low for North Island Tues/Wednesday

Unread post by NZstorm »

The system will pass off just to the east of us now by the looks. I hope we still get some rain here in Auckland but with a S/SE we could miss out.
spwill
Posts: 9407
Joined: Sun 29/06/2003 22:39
Location: Mt Eden Auckland
Has thanked: 472 times
Been thanked: 541 times

Re: Low for North Island Tues/Wednesday

Unread post by spwill »

Looks like another sub tropical Low will be moving down later in the month. Bad news for holiday makers but atleast it's another rain opprotunity for farmers.
User avatar
Nev
Moderator
Posts: 5731
Joined: Tue 07/03/2006 15:24
Location: Waiheke Island, Hauraki Gulf
Has thanked: 326 times
Been thanked: 631 times

Re: Low for North Island Tues/Wednesday

Unread post by Nev »

Yes, ideally we'd be very happy if our tanks were topped up before Xmas - here's hoping!

MetService have a Gale warning in force for the Hauraki Gulf later this morn. Was relatively calm and sunny here earlier, but, about 100 km NE of Akld, winds at 7am were already at 67 km/h.
Manukau heads obs
Posts: 12305
Joined: Mon 10/03/2003 16:30
Location: West Coast Road, Manukau Peninsula, North Island
Has thanked: 0
Been thanked: 0
Contact:

Re: Low for North Island Tues/Wednesday

Unread post by Manukau heads obs »

still looking like some usefull rain me thinks for the auckland area are a coming :)
Image
Brian Hamilton, weather enthusiast. My weather dataEmail: [email protected]
User avatar
Tornado Tim
Moderator
Posts: 4896
Joined: Sun 19/10/2008 17:17
Location: Raglan, Waikato / Hillcrest, Hamilton
Has thanked: 92 times
Been thanked: 178 times
Contact:

Re: Low for North Island Tues/Wednesday

Unread post by Tornado Tim »

Northern Waikato has got some Altocumulus Castellanus.
If this South Easterly continues, Waikato might get a thunderstorm later on.
The GFS does not think so..... it seems to think all the instability has shifted past the coromandel area.
We will see.
You do not have the required permissions to view the files attached to this post.
NZAPStrike.net - NZ Aus Pacific Strike Network
User avatar
Vertigo
Posts: 1181
Joined: Sun 09/12/2007 23:50
Location: Grafton, Auckland
Has thanked: 0
Been thanked: 7 times
Contact:

Re: Low for North Island Tues/Wednesday

Unread post by Vertigo »

an interesting spin-up west of cape reinga this morning, associated with the ex-tropical low moving east of us. looks like a small cyclone in its startup stages, but much too shallow.
You do not have the required permissions to view the files attached to this post.
Collated weather maps @ http://ohthehugemanatee.com/weather/
User avatar
Nev
Moderator
Posts: 5731
Joined: Tue 07/03/2006 15:24
Location: Waiheke Island, Hauraki Gulf
Has thanked: 326 times
Been thanked: 631 times

Re: Low for North Island Tues/Wednesday

Unread post by Nev »

Was 21°C here just after midday - down to about 15°C now. Light rain from about 4pm. The highest of the E'erly winds predicted for the Hauraki Gulf earlier today seem to be staying well offshore...

Mean Winds at 4pm:
Waitemata Harbour - 44 km/h
Tiritiri Lighthouse - 61 k/h
Colville Channel - 82 km/h
Mokohinau Islands - 85 km/h
User avatar
David
Posts: 7189
Joined: Sat 18/08/2007 21:02
Location: Howick, Auckland
Has thanked: 346 times
Been thanked: 543 times
Contact:

Re: Low for North Island Tues/Wednesday

Unread post by David »

Rain arrived here around 5pm but is very intermittent - up to 5mm so far from quick heavier bursts mainly. Interestingly the SE has completely died off and there is now a southerly with only 14C? :?
Image
User avatar
Vertigo
Posts: 1181
Joined: Sun 09/12/2007 23:50
Location: Grafton, Auckland
Has thanked: 0
Been thanked: 7 times
Contact:

Re: Low for North Island Tues/Wednesday

Unread post by Vertigo »

large dollop of red on the latest auckland rain radar! brian, did you catch that? looks close to you.
also noticing some electrical activity around this system.
You do not have the required permissions to view the files attached to this post.
Collated weather maps @ http://ohthehugemanatee.com/weather/
spwill
Posts: 9407
Joined: Sun 29/06/2003 22:39
Location: Mt Eden Auckland
Has thanked: 472 times
Been thanked: 541 times

Re: Low for North Island Tues/Wednesday

Unread post by spwill »

There was a brief Thunderstorm out in the Hauraki Gulf between Waiheke and Coromandel .
Up to 22C today with a sunny morning. Rain now, heavy at times, 14C.
Manukau heads obs
Posts: 12305
Joined: Mon 10/03/2003 16:30
Location: West Coast Road, Manukau Peninsula, North Island
Has thanked: 0
Been thanked: 0
Contact:

Re: Low for North Island Tues/Wednesday

Unread post by Manukau heads obs »

we have had some good rain here so far....11mm now :)
looks like there was some lee trough amplificaiton going on there Vertigo
Image
Brian Hamilton, weather enthusiast. My weather dataEmail: [email protected]
User avatar
Nev
Moderator
Posts: 5731
Joined: Tue 07/03/2006 15:24
Location: Waiheke Island, Hauraki Gulf
Has thanked: 326 times
Been thanked: 631 times

Re: Low for North Island Tues/Wednesday

Unread post by Nev »

Interesting - must've missed those strikes. Over 19mm here so far, Kerikeri nearly up to 60mm and both Whangarei and the Coromandel's Pinnacles over 30mm.
User avatar
NZstorm
Posts: 11333
Joined: Mon 10/03/2003 19:38
Location: Grey Lynn, Auckland
Has thanked: 342 times
Been thanked: 361 times

Re: Low for North Island Tues/Wednesday

Unread post by NZstorm »

27mm at Grey Lynn so far this evening. This system certainly did amplify. You can see that unstable air/cbs out to the east of Northland on sat pic.
User avatar
CHCH Weather Chaser
Posts: 3460
Joined: Thu 26/06/2008 16:10
Location: Halswell / Hoon Hay Christchurch
Has thanked: 0
Been thanked: 0

Re: Low for North Island Tues/Wednesday

Unread post by CHCH Weather Chaser »

Looks very neat the Auckland radar, has done for a few hours now. Looks like it is fairly slow moving as well! Some good rain totals to be made by the looks of it. Possibly another one coming next Tuesday as some models are picking. Very strong winds here at the moment in Christchurch, fine with a NE gusting up to 65km/h.
Reporting Live from Southern Christchurch
Leighton Thomas

2014 Rainfall: Jan: 21mm Feb: 76mm March: 170mm April: 201mm YTD: 468mm
Manukau heads obs
Posts: 12305
Joined: Mon 10/03/2003 16:30
Location: West Coast Road, Manukau Peninsula, North Island
Has thanked: 0
Been thanked: 0
Contact:

Re: Low for North Island Tues/Wednesday

Unread post by Manukau heads obs »

50mm here now, to 5:45 am, and still raining nicely
great xmas present for the farmers in the district!
Image
Brian Hamilton, weather enthusiast. My weather dataEmail: [email protected]
User avatar
Vertigo
Posts: 1181
Joined: Sun 09/12/2007 23:50
Location: Grafton, Auckland
Has thanked: 0
Been thanked: 7 times
Contact:

Re: Low for North Island Tues/Wednesday

Unread post by Vertigo »

just a question.. the latest 1am skew-t diagram for whenuapai shows pretty much constant 100% humidity all the way up to 500mb, and even further up its not much lower than 80%.. is this contributing to the heavy rainfall we are seeing from this system? never quite seen a diagram like this. its like the air is wringing water from itself.
You do not have the required permissions to view the files attached to this post.
Collated weather maps @ http://ohthehugemanatee.com/weather/
User avatar
NZstorm
Posts: 11333
Joined: Mon 10/03/2003 19:38
Location: Grey Lynn, Auckland
Has thanked: 342 times
Been thanked: 361 times

Re: Low for North Island Tues/Wednesday

Unread post by NZstorm »

Yes, thats an impressive sounding. The precipitable water is 36mm which is a very high number for a sounding with surface dewpoint of just 12C! All that moisture in the middle of the sounding is where the rain obviously is coming from.

The GFS yesterday was forecasting 65mm for Auckland and Massey recorded 62mm! Grey Lynn got 42mm.
Locked