Unstable Sunday 5th to Monday 6th North Island

[NZstorm]

An active trough develops out to the west of the North Island tomorrow. A front with possible thunder afternoon/evening in western and northern areas. Hail and squalls also on the cards.

500mb chart for tomorrow 6pm.

[Tornado Tim]

Tonights Metservice Outlook looks interesting.... Tomorrow afternoon looks quite nice

Tomorrow Morning: - 5th May, 2013

Valid to: Noon Sunday 5 May 2013
Issued at: 9:04pm Saturday 4 May 2013
A front is forecast to move across the central North Island Sunday morning and weaken. There is a moderate risk of a few thunderstorms about coastal parts of Bay of Plenty and northern Gisborne in the early hours of Sunday, with a low risk extending down to northern Taranaki and Hawkes Bay. Any thunderstorms that eventuate here could produce localised heavy rain of up to 25mm/hr.

Later in the morning, a more mobile front is expected to move out of the north Tasman Sea onto the northern North Island, with a band of heavy showers and squally thunderstorms. There is a moderate risk of thunderstorms about Northland late morning, and in Auckland around the middle of the day. Brief heavy rain, hail, and squally northwesterly winds gusting 90-110km/hr can be expected with these thunderstorms. There is however a low risk one or two of these storms could be SEVERE, producing potentially damaging gusts in excess of 110km/hr and possibly a small tornado.

In the South Island, a front over southern Westland and northern Fiordland Saturday night bringing heavy rain to these areas should weaken during Sunday morning. There is a moderate risk of embedded thunderstorms in these areas before dawn, producing localised heavy rain in the 10-25mm/hr range.

Finally, there is a low risk of thunderstorms embedded in areas of rain about Nelson during the morning, as indicated on the chart.

No other thunderstorms or severe convection expected over New Zealand on Sunday morning.

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Tomorrow Afternoon/Evening: - 5th May, 2013

Issued at: 9:06pm Saturday 4 May 2013

Updated at 9.05pm Saturday

Over the northern half of the North Island, northwesterlies are expected to strengthen during the second half of Sunday.

An organised band of heavy showers and thunderstorms should move across areas from Auckland to Taranaki, Taupo and Bay of Plenty during the afternoon, then be followed by further heavy showers and isolated thunderstorms (especially near the west coast) in a strong northwest flow.

There is a moderate risk of a few thunderstorms over the northern half of the North Island, especially from about Auckland southwards. These thunderstorms will be very squally, producing brief heavy rain, hail, and gusts to 110 km/hr. However, there is a continued low risk of one or two SEVERE thunderstorms producing potentially damaging gusts in excess of 110km/hr and possibly a small tornado.

Around central New Zealand, there is a moderate risk of thunderstorms about Wairarapa from Sunday evening, and Marlborough at night, embedded in a broad scale rainband. If these thunderstorms occur, they will boost local rainfall rates into the 10-25mm/hr range.

Finally, because the atmosphere will become increasingly unstable over northern and central New Zealand on Sunday afternoon and evening, there is a broad low risk area covering everywhere else north of Ashburton and Kahurangi National Park, as indicated on the chart.

No thunderstorms expected elsewhere, however a strong cold southeasterly flow will bring heavy rain to southern and eastern parts of the South Island. See latest Severe Weather Warning and Watch for more details.

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[Michael]

Believe it when I see it...Gale NW,When that last happen,last winter a day or 2.

[Manukau heads obs]

wow, low looks great on latest sat image
warm and cold front spirrling into low center and all

[NZstorm]

Cold front due in Auckland/Waikato this afternoon. Dewpoints will be 14C ahead of the cold front which should be enough for a few thunderstorms to develop. I'm considering driving down to western Waikato pm.

The gradient tightens up later today over the upper North Island which means some big squall gusts in exposed areas.

[spwill]

See what can develop today, currently can see towering cumulus showers over the warm Gulf, scrappy Cb over the sea to the west, 14C, dewpoint 13.7C, light northeast wind.

Some fog here earlier

[David]

Had an extra 10mm here between 1.30am and 2am, heavy enough to stir me from my sleep

[David]

Mostly sunny morning here so far, barely a breath of wind too... went for a walk just after 8am, was really nice. Hadn't been expecting such good conditions given the forecast!

[Philip Duncan]

Should've checked out forecast David! We have light winds for this morning - just like we weren't predicted heavy rain and thunder all across Saturday morning!

[Manukau heads obs]

we are in between a departing low and an incoming low though
the barometer is dropping steadily
lots of high cloud sheets coming off the warm front here

the NW wind is increasing at Cape reinga

[NZstorm]

Front has just gone through here with a short period heavy rain.

Anyone else missing the weatherzone satellite pics today, don't seem to be updating.

[Michael]

the low is further away than expected ,the westerly may pickup over night as it moves over the NI

Mostly sunny morning here so far, barely a breath of wind too... went for a walk just after 8am, was really nice. Hadn't been expecting such good conditions given the forecast!

[NZstorm]

Observed sounding from Whenuapai today 00Z.

Marginally unstable.

[Michael]

Not a breath of wind out there now.

[seej]

Slight breeze here.

[spike_01]

Still an awesome day in Wellington.. But that will change as the day goes on.. Tomorrow will be interesting for sure..

[Manukau heads obs]

thunder heard here

[Thunder]

I've been missing the weatherzone sat pics also Steven, hope they come back soon!

[spwill]

A cool showery mess here this afternoon with isolated lightning strikes showing up.

[Manukau heads obs]

I see stronger winds are starting to move into the far north now
you can see that on the sat image

[littleheaven]

How long before it hits Auckland, do you think? I'm a bit nervous about my new pergola roof, although we're pretty sheltered from all but a straight-on southerly.

[NZstorm]

How long before it hits Auckland, do you think? I'm a bit nervous about my new pergola roof, although we're pretty sheltered from all but a straight-on southerly.

WNW gusts to 50knots are possible in exposed parts of Auckland this evening and early morning associated with any shower activity that occurs. More likely out Brian's way I think.

[seej]

Very gusty here now with moderate rain.

[ScottyD]

I've also noticed the increase in wind over the last hour

[Nev]

Blowing a gale out this way. I see the Waitemata Harbour's Bean Rock had mean-winds of 63km/h at 9pm and 83km/h way out in the outer Gulf's Mokohinau Islands.