Moist and unstable week starting Jan 27th

treetop · Unread post by **treetop** » Sat 30/01/2016 23:35

Thanks for capturing that Tim {Mum] Had a similer storm a month ago over Rotorua.Not sure if we will get anything more tonight now, off to bed I suppose.

jamie · Unread post by **jamie** » Sun 31/01/2016 06:40

The trough has just gone thru here I think.

NZstorm · Unread post by **NZstorm** » Sun 31/01/2016 07:37

That Bay of Plenty storm dropped 27mm in an hour Matata.

Today the best instability is in the first half of the afternoon, it looks to weaken after 03Z, especially south of Auckland.

treetop · Unread post by **treetop** » Sun 31/01/2016 07:41

oh, was thinking about a chase today ? The Waikato needs a fine morning and some good sea breeze feed in from the Gulf. Overcast/dry/dull here, hopefully cloud cover just this side

jamie · Unread post by **jamie** » Sun 31/01/2016 08:03

Yup fine morning here. Lots of sunshine

spwill · Unread post by **spwill** » Sun 31/01/2016 08:07

Great clip Tim, always great when you can see the Cb top lighting up.

Some sunshine here with medium level cloud, 22C, dewpoint 20C, light winds.

How much will the upper level warming later affect storm chances today ?

jamie · Unread post by **jamie** » Sun 31/01/2016 08:20

Something is going up over Tauranga way on that trough.

ImageUploadedByTapatalk1454181599.970700.jpg

treetop · Unread post by **treetop** » Sun 31/01/2016 09:03

We are on the edge of it.Been building along the coast and moving out to sea ,looking at that photo I would expect a few rumbles by now ???. If Waikato is fine /clear I think any storms will backbuild westward and be slow moving.

Tornado Tim · Unread post by **Tornado Tim** » Sun 31/01/2016 09:21

Looking good:

Issued at: 9:02am Sunday 31 Jan 2016

A trough will move north up the east coast of the Coromandel Peninsula this morning and then rotate over Auckland and Northland this afternoon as an upper trough moves to the northeast. The surface trough reinforces the afternoon wind convergence due to daytime heating from western Northland down through western Auckland and into Waikato. With the airmass still being warm and moist,widespread showers are expected to be triggered.

This morning, there is a moderate risk of thunderstorms about the east Coromandel coast north of Tauranga which may give local rainfall rates of 10 to 25+mm/hr. This threat is expected to have passed by early afternoon.

There is now a high risk of scattered SEVERE THUNDERSTORMS over western parts of Northland and Auckland this afternoon, and over western Waikato as far south as Raglan into the evening. These have the potential to deliver rainfall rates of 25 to 40mm/hr or more, and hail of 10-20mm diameter.

For the remainder of Northland, Auckland, and western Bay of Plenty, there is a moderate risk of thunderstorms this afternoon and early evening having the potential for rainfall rates of 10-25mm/hr, and a lower risk of localised downpours of 25-40mm/hr and small hail.

These high rainfall rates have the potential for flash flooding, slips and to make driving very difficult. A SEVERE THUNDERSTORM watch will be issued this morning.

A surrounding envelope of low thunderstorm risk extends south from Waitomo to Taupo, to eastern Bay of Plenty.

Elsewhere, no thunderstorms or significant convection expected.

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Resulting Severe Thunderstorm Watch:

Issued by MetService at 09:14 am Sunday 31 January 2016
Valid until 09:00 pm Sunday 31 January 2016
This watch affects people in the following weather forecast districts:
Northland
Auckland
Waikato

A trough will rotate over Auckland and Northland this afternoon as an upper

trough moves to the northeast. The surface trough reinforces the afternoon wind

convergence due to daytime heating from western Northland down through western

Auckland and into Waikato. With the airmass still being warm and moist, widespread showers and thunderstorms are expected to be triggered. Some of these thunderstorms are likely to become SEVERE by early afternoon and have the potential to deliver rainfall rates of 25 to 40mm/hr or more. This activity will move offshore from Northland and Auckland by evening, but will remain in western Waikato until about mid evening.

Rainfall of this intensity can cause flash flooding, especially about low-lying areas such as streams, rivers or narrow valleys, and may also lead to slips. Driving conditions will also be hazardous with surface flooding and poor visibility in the heavy rain.

In addition, there maybe some localised hail in the 10 to 20mm diameter range.

Note: A Severe Thunderstorm Watch means conditions are favourable for severe thunderstorms in and close to the watch area. People in these areas should be on the lookout for threatening weather conditions and listen for possible Severe Thunderstorm Warnings.

Issued by: Paul Mallinson

This watch will be updated by: 02:00 pm Sunday 31 January 2016

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Tornado Tim · Unread post by **Tornado Tim** » Sun 31/01/2016 09:47

Warrants an impromptu Weather Meet I think. Depends where you want to chase, you going to be lumbered into two Camps (Auckland - Northland) or North Waikato to Central West Waikato.

Im going to get my Gym session out of the way first before the big instability numbers start to pop up. Feel free to contact me though and hopefully we can get a proper chase going today.

jamie · Unread post by **jamie** » Sun 31/01/2016 09:51

I have a party to be at over the middle of the day but i should be free by 2-3. I just hope its not too late by then.

I will then head towards Mercer and then decide from there if i head North Waikato's or South Auckland's west coast. The Waikato river could become a downer regarding chasing today. If your at the port you have to drive all the way back to the Tuakau bridge and then back to Waiuku to continue chasing up the coast towards Brians.

treetop · Unread post by **treetop** » Sun 31/01/2016 10:10

I may do a circuit to Paeroa/Cambridge and back to TGA PM, not keen to waste petrol in West Waikato unless looking really good

treetop · Unread post by **treetop** » Sun 31/01/2016 10:20

Heard a rumor of 40mm hail at around 730 Pm Edgecome area ? Hard to get any decent reports [not enough weather nuts !! ]

Orion · Unread post by **Orion** » Sun 31/01/2016 10:30

Spectacular video of the lightning in the cloud-tops, Tornado Tim - my compliments to the videographer!

Richard · Unread post by **Richard** » Sun 31/01/2016 11:04

Good luck to all those who are hoping in ya cars chasing, look forward to the photos later.

How much long did that storm keep it up for Tim

Orion · Unread post by **Orion** » Sun 31/01/2016 11:13

Auckland Civil Defence notification: http://www.aucklandcivildefence.org.nz/ ... cy-status/

Sunday 31 January 2016 11:07 AM

Current Situation
MetService have advised that there is a HIGH risk of severe thunderstorms which may form on mainland Auckland today. Some storms may impact Waiheke Island, the Hauraki Gulf and Great Barrier but these are not expected to be as intense.

Auckland will start to see showers forming soon, and thunderstorms between 2pm and 5pm, some of these these thunderstorms are likely to become SEVERE and they have potential to deliver rainfall rates of 25 to 40mm/hr. Hail between 10 and 20mm is also possible.

Where thunderstorms form, surface flooding is likely and localised flooding of streams, may occur.

Small localised tornadoes can be associated with severe thunderstorms.

- See more at: http://www.aucklandcivildefence.org.nz/ ... Lj128.dpuf

spwill · Unread post by **spwill** » Sun 31/01/2016 11:40

Some towering Cu around now but no real convergence yet.

jamie · Unread post by **jamie** » Sun 31/01/2016 11:48

Great towers tho! As seen here.

ImageUploadedByTapatalk1454194115.446623.jpg

spwill · Unread post by **spwill** » Sun 31/01/2016 12:01

A local T Cu

Brassnz · Unread post by **Brassnz** » Sun 31/01/2016 12:13

Am just leaving Pukekohe now, and heading home to Laingholm. Looks promising down this way with lots of buildups all around. Good luck to today's chasers.

NZstorm · Unread post by **NZstorm** » Sun 31/01/2016 12:53

Temp 27 with dp 20 at the airport.

Can see cb tops to SE. (from the showers over north Waikato).

Paul Mallinson · Unread post by **Paul Mallinson** » Sun 31/01/2016 12:55

T=26.5C and Dewpoint = 19.0C gives a CAPE of 1815 on the midday Whenuapai sounding and a lifted index of -5.4C

David · Unread post by **David** » Sun 31/01/2016 13:07

A very humid day in Howick with 21-22C dewpoint. Big convection visible to the S/SE of here

David · Unread post by **David** » Sun 31/01/2016 13:10

According to Metservice on twitter, a storm cell dropped 41mm on Great Barrier Island in an hour a little earlier

GraemeWi · Unread post by **GraemeWi** » Sun 31/01/2016 13:22

Dark base to my north west, looks to be near the coast towards Muriwai, a good anvil off to the north near the Kaipara, and a distant anvil out to the east maybe Coromandel way. Fingers crossed for some action around Auckland

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