Unsettled weather & possible thunderstorms, 28-30 Dec

David · Unread post by **David** » Fri 27/12/2013 12:38

Looks like it's time for a new thread for the incoming unsettled weather. A low from the north looks set to bring rain and possible thunderstorms to the north Sat night through Sunday. Also looks to be a low crossing the South Island Monday 30th.

Looks like thunderstorms possible in many areas Sunday & Monday, especially in the afternoons/evenings. Here is a chart showing CAPE for 4pm Sunday 29th.

CAPE4pm29Dec2013.png

tgsnoopy · Unread post by **tgsnoopy** » Fri 27/12/2013 12:42

Excellent. Mental note, keep Sunday free.

spwill · Unread post by **spwill** » Fri 27/12/2013 17:56

Dewpoint chart for Sunday, afternoon sunshine is what we are after.

NZstorm · Unread post by **NZstorm** » Fri 27/12/2013 18:07

I wouldn't rule out an isolated tornado with that system in the north later Saturday/early Sunday.

Dean. · Unread post by **Dean.** » Sat 28/12/2013 08:10

Steady rain all night in Hanmer.Plenty of water under the tent.Love NZ summers!

NZstorm · Unread post by **NZstorm** » Sat 28/12/2013 08:40

Clear morning in Queenstown. Forecast sounding shows trigger temp for convection 24C.

GreggWard · Unread post by **GreggWard** » Sat 28/12/2013 09:12

Far less low cloud here today, with the sun streaming down, so should be better for the storms they are forecasting below:

GreggWard · Unread post by **GreggWard** » Sat 28/12/2013 09:55

I hope all of that mid-high level cloud from the new low out to the NW doesn't dampen things down too much.

David · Unread post by **David** » Sat 28/12/2013 10:09

Severe weather watch issued for heavy rain
http://www.metservice.com/national/warn ... ther-watch

Valid to 9:55am Sunday 29 Dec 2013

SEVERE WEATHER WATCH FOR NORTHLAND, AUCKLAND, COROMANDEL PENINSULA, BAY OF PLENTY ROTORUA, GISBORNE

ISSUED BY METSERVICE AT 0955hrs 28-Dec-2013

BURST OF HEAVY RAIN FOR THE NORTHEAST OF NORTH ISLAND TONIGHT AND SUNDAY.

A low over the Tasman Sea will spread a very moist and unstable northerly airstream over the upper North Island during today and Sunday. Fronts associated with this low should bring a burst of heavy thundery rain to the upper North Island.

The heaviest falls are likely in Northland this evening and early Sunday morning and in Auckland during Sunday morning and about the Coromandel Peninsula Sunday morning and early afternoon. For Bay of Plenty and the northern and western ranges of Gisborne the heaviest falls are likely during Sunday and early Monday morning.

This Watch is for the possibility of rainfall accumulations reaching warning criteria in these areas.

A few isolated areas may possibly reach warning amounts due to the embedded convection (especially in Bay of Plenty and the ranges of Gisborne), but at this stage models indicate that the rainfall distribution is not widespread enough to warrant a full warning.

MetService will continue to monitor the situation and advises people to keep up to date with the latest forecasts in case any areas in this Watch are upgraded to a full Warning.

This Watch will be reviewed by 9pm Saturday 28 December 2013

Storm Struck · Unread post by **Storm Struck** » Sat 28/12/2013 10:32

Getting some good steady showers wafting in from the east here, MS says low risk thunder slightly north of here but I think we will see some sunshine between midday and 3pm before rain redevelops overnight.

Nev · Unread post by **Nev** » Sat 28/12/2013 11:31

Here's tomorrow's T-Storm Outlook (also a high-risk for Northland this evening)...

MetService - Severe Thunderstorm Outlook

Valid to: Noon Sunday 29 Dec 2013
Issued at: 10:12am Saturday 28 Dec 2013

An active front is expected to move across Northland and Auckland, and onto the Coromandel Peninsula and western Bay of Plenty during the morning, bringing a burst of heavy rain as detailed in latest SEVERE WEATHER WATCH. There is a high risk of embedded thunderstorms with this front, with may produce localised rainfall rates up to 25mm/hr. A lesser risk of thunderstorms extends over Waikato and eastern Bay of Plenty. Sea breeze convergences are expected to develop showers over the Fiordland Lakes and Southern Lakes regions late morning, with a low risk of one or two thunderstorms.

No thunderstorms expected over the remainder of New Zealand.

MetService T-Storm Outlook to Noon 29th - Is. Dec 28, 10.12am.png
Valid to: Midnight Sunday 29 Dec 2013
Issued at: 10:19am Saturday 28 Dec 2013

The active front should bring a burst of heavy rain to Coromandel Peninsula and Waikato in the afternoon, and to the Bay of Plenty during the afternoon and evening. See the latest SEVERE WEATHER WATCH for details. There is high risk of embedded thunderstorms with this front, which may produce localised rainfall rates of 25mm/hr. A lesser risk of thunderstorms extends across Waitomo, Taranaki and Taupo with the passage of this front.

Behind the front, afternoon convergence zones are expected to set up across Waikato, Auckland and southern Northland, bringing a few heavy showers and a low risk of thunderstorms.

As a low approaches Northland at night, heavy showers are likely there, along with a low risk of a few thunderstorms.

Over the South Island, sea breeze convergences are expected in the south and west, along with cold temperatures in the upper atmosphere. There is a moderate risk of thunderstorms across western parts of Southland and the Otago Southern Lakes, which may produce localised rainfall rates of 10 to 25mm/hr. A lesser risk of thunderstorms extends over the Southern Alps.

No thunderstorms expected over the remainder of New Zealand.

MetService T-Storm Outlook to Midnight 29th - Is. Dec 28, 10.19am.png

jamie · Unread post by **jamie** » Sat 28/12/2013 11:59

We had a heap of Mammatus move over not too long ago within the overcast sky. Sign of thing destabilizing above?

spike_01 · Unread post by **spike_01** » Sat 28/12/2013 15:03

Nice big thunder cloud just north of Wellington right now

spike_01 · Unread post by **spike_01** » Sat 28/12/2013 15:06

Pic never attached

http://s1177.photobucket.com/user/tiger ... 3.jpg.html

Nev · Unread post by **Nev** » Sat 28/12/2013 17:53

Yes, just managed to grab the last T-Storm Warning for Carterton and Masterton. Presumably there were earlier ones around that area?

I see WW have nice pic of a funnel cloud around the Hauraki Plains this arvo.

spwill · Unread post by **spwill** » Sat 28/12/2013 18:08

Certainly a funnel cloud there, thanks Nev.

A few drops of rain here late morn/early afternoon, temp max low 20s today.

Thunder081 · Unread post by **Thunder081** » Sat 28/12/2013 18:09

These pictures are from then CB's currently north of Palmerston North taken from Levin.

GreggWard · Unread post by **GreggWard** » Sat 28/12/2013 19:11

Went for a long drive today, but only saw one good CG lightning stroke, from this storm just NW of Halcombe.

David · Unread post by **David** » Sat 28/12/2013 19:59

Metservice 3 day model consistently forecasting 50+ mm for Auckland city area, but GFS going for a more modest 25-30 mm. Either way, I get to avoid garden-watering again for a while

Thunder081 · Unread post by **Thunder081** » Sat 28/12/2013 22:33

Today I went for a chase to Foxton where Metservice had issused a severe thunderstorm warning for. Whilst on the Foxton bridge it rained very heavy possibly torrential. I didn't see any lightning but heard some thunder. Whilst in Foxton as the storm moved away towards Waitarere I witnessed an updraft close to the ground that lasted for a few seconds. There was also some surface flooding in Foxton. YouTube video coming tonight or tomorrow.

- Thunder081

Manukau heads obs · Sun 29/12/2013 05:57

you have done very well so far David for rain I see

jamie · Unread post by **jamie** » Sun 29/12/2013 06:03

Wow David you have had a good drink. Rain really only just starting here.

spwill · Unread post by **spwill** » Sun 29/12/2013 07:19

Rain has eased here, the 20mm will be good for the garden/lawns. Can see blue sky in the west but that may take a while to move in. Some thunder activity off shore Northland

Nev · Unread post by **Nev** » Sun 29/12/2013 07:25

We've had 52mm here so far this morn.

ben g · Unread post by **ben g** » Sun 29/12/2013 07:34

Had some very good rain last nite in mangawai, the unofficial "depth of water in the pint glasses left out side gauge", shows about 65-70mm. Good Xmas prezzie for the farmers up here

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