Metservice wrote:Valid to: Midnight Thursday 9 Jan 2014
Issued at: 10:46am Wednesday 8 Jan 2014
The central and eastern North Island is expected to be very unstable on Thursday afternoon and evening, with the combination of daytime cloud buildups, a southerly wind change and cold temperatures aloft producing scattered heavy showers and thunderstorms from Waikato and Bay of Plenty through to Gisborne and Hawkes Bay. These thunderstorms will produce localised heavy rain or downpours up to 25mm/hr (or possibly a little higher in some places), and hail of 10-20mm diameter.
A lower risk of thunderstorms covers Northland and northern Auckland in the afternoon, and also a broad area from South Auckland and Coromandel through to northern Taranaki, inland Wanganui and northern Manawatu as indicated on the chart.
In the South Island, daytime cloud buildups should produce scattered showers about Nelson, inland Marlborough and Buller, with a low risk of thunderstorms as indicated on the chart.
No other thunderstorms or significant convection expected over New Zealand on Thursday afternoon and evening.
Unstable Jan 9th - North Central North Island
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For today's weather discussion head to: New Zealand Weather & Climate
- Tornado Tim
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Unstable Jan 9th - North Central North Island
Looks like a good day for chasing tomorrow, if storms develop on the southerly change, it will be a linear setup, but it will be much more widespread.
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Re: Unstable Jan 9th - North Central North Island
It is a particularly cold upper level trough for January, should be plenty of hail tomorrow. Hopefully the day is not too messy. I will likely chase.
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Re: Unstable Jan 9th - North Central North Island
I will probably Join you.....spwill wrote:It is a particularly cold upper level trough for January, should be plenty of hail tomorrow. Hopefully the day is not too messy. I will likely chase.
PM me your cell and hopefully we can meet up.
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Re: Unstable Jan 9th - North Central North Island
There is something i dont particuarly like about this but i cant put my finger on what it is. Perhaps its that i have not seen a setup like this in Jan so i have no experience to call back on.
Perhaps im thinking of this setup as a winter one. In winter we would get a couple of light showers, mostly south of Hamilton. We remain quite dry on a SW. But i suppose being summer there is the extra heat. How about moisture though? In winter the air is more easily saturated. Will there be enough moisture to get a good storm going?
Sorry just thinking outloud there.
Perhaps im thinking of this setup as a winter one. In winter we would get a couple of light showers, mostly south of Hamilton. We remain quite dry on a SW. But i suppose being summer there is the extra heat. How about moisture though? In winter the air is more easily saturated. Will there be enough moisture to get a good storm going?
Sorry just thinking outloud there.
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Re: Unstable Jan 9th - North Central North Island
I will chase if something shows promise (like a nice linear line)
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Re: Unstable Jan 9th - North Central North Island
I think SE of your location Jamie, the southern Hauraki Plains could be a good starting point early tomorrow afternoon. Hoping for plenty of sunshine in between the showers tomorrow.
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Re: Unstable Jan 9th - North Central North Island
The trop is just shy of 300hpa tomorrow, so any potential Cb's will be of moderate size. Might be worth taking a sweatshirt tomorrow, esp if that southerly is cold.
Hopefully plenty of sunshine tomorrow, any temps over 22 will be very much appreciated
Hopefully plenty of sunshine tomorrow, any temps over 22 will be very much appreciated
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Re: Unstable Jan 9th - North Central North Island
Trying to keep the afternoon clear. Will see if I can make it if it looks promising.
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Re: Unstable Jan 9th - North Central North Island
coastal BOP may be worth a look as the westerly may run down the coast [under warm conditions hopefully] and provide some good fuel for the incoming S change ,verycold upper level temps should create some additional drama.
ttttttttttt
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Re: Unstable Jan 9th - North Central North Island
Updated Outlook:
Metservice wrote: Very unstable conditions are expected to affect the central and eastern North Island on Thursday afternoon and evening, with the combination of daytime cloud buildups, a southerly wind change and cold temperatures aloft producing heavy showers and a high risk of thunderstorms from Waikato and Bay of Plenty through to Gisborne and inland Hawkes Bay as indicated on the map. These thunderstorms will produce localised heavy rain or downpours up to 25mm/hr (or possibly a little higher in some places), and hail of 10-20mm diameter.
A lower risk of thunderstorms covers much of the remainder of the North Island,from Hawkes Bay through the north of Taihape and Taranaki northwards as indicated on the chart.
In the South Island, daytime cloud buildups should produce scattered showers about Nelson, inland Marlborough and Buller, with a low risk of thunderstorms as indicated on the chart.
No other thunderstorms or significant convection expected over New Zealand on Thursday afternoon and evening.
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Unstable Jan 9th - North Central North Island
Turns out I'm heading to Taihape tomorrow afternoon so ill try time it that I can drive straight through some action.
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- NZstorm
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Re: Unstable Jan 9th - North Central North Island
I can't recall the last time I saw polar airmass thunderstorms in the Tasman Sea in January!
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Re: Unstable Jan 9th - North Central North Island
Just for the record. 500mb chart for midday.
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Re: Unstable Jan 9th - North Central North Island
yes, there was some nice looking CB blown off top anvils just south of me first thing
and one out to the NW of me now
yes a winter looking sky
and one out to the NW of me now
yes a winter looking sky
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Re: Unstable Jan 9th - North Central North Island
A 16C start to the day here which is about average but you can see the upper air is very cold with some towering Cu/ Cb in the area. Dewpoint is 13C .
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Re: Unstable Jan 9th - North Central North Island
Didnt hear that, oh well.....jamie wrote:Thunder here! Quite a cold nip in the air too.
Seems there is little bit of Lightning in the Storms that have developed in the SW flow.
Certainly shows that the atmosphere is very unstable when there is Lightning early in the morning....
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Re: Unstable Jan 9th - North Central North Island
Just released Thunderstorm Outlook:
Metservice wrote: A very unstable south to southwesterly flow will cover northern and central New Zealand today, with the combination of cold temperatures aloft, daytime cloud buildups, and a southerly wind change over the central North Island this afternoon and evening producing heavy showers and thunderstorms in many areas.
In Northland, Auckland, and near the west coast from Taranaki northwards, the main risk of thunderstorms is this morning and early afternoon, with the thunderstorm activity easing by evening. Brief heavy rain and hail will accompany these thunderstorms.
Over the central North Island from Waikato and Bay of Plenty southwards to the central high country and Hawkes Bay, there is a high risk of thunderstorms this afternoon and evening, mostly on a southerly wind change. These thunderstorms will be accompanied by localised heavy rain, squally winds and hail. Over eastern Bay of Plenty, Rotorua, Taupo, and inland Hawkes Bay and Gisborne, a few of these thunderstorms are likely to be severe with localised downpours of 25-40mm/hr and larger hail.
A low risk of thunderstorms covers all other North Island areas from northern Manawatu northwards through the day.
In the South Island, there is a low to moderate risk of thunderstorms about Nelson, Buller and western Marlborough, with the main risk of thunderstorms about the Nelson area this afternoon. Localised heavy rain and hail will accompany these storms.
No other thunderstorms or significant convection expected over New Zealand today.
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Re: Unstable Jan 9th - North Central North Island
I am up for a chase...maybe I could get join up at bombay...let me know...time to meet
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Re: Unstable Jan 9th - North Central North Island
what time will this southerly move up? Ill try time my trip south so im in tirau area ready for it. Does 3pm at tirau sound safe?
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Re: Unstable Jan 9th - North Central North Island
Unfortunately its a big drive from Auckland down to the thunderstorm zone which looks south and east of Tirau.
Surface southerly creeps up during the afternoon. A sea breeze in the BOP would spice up convection there.
Surface southerly creeps up during the afternoon. A sea breeze in the BOP would spice up convection there.
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Re: Unstable Jan 9th - North Central North Island
I am up for a South Waikato Chase.... Hopefully it goes off this time, other times I have chased a high risk and it came to nothing, LOL
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Re: Unstable Jan 9th - North Central North Island
yeah...I did wonder about having to drive that far south...
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Re: Unstable Jan 9th - North Central North Island
Just done some looking and the southerly is on Palmerston Norths door step right now. Doesnt look to be moving all that fast.NZstorm wrote:Surface southerly creeps up during the afternoon. A sea breeze in the BOP would spice up convection there.
But the 12z GFS shows it at taupo by 1pm. Well into BOP at 4pm.
Oh yes a sea breeze there will really get things going!
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Re: Unstable Jan 9th - North Central North Island
GFS surface wind chart for 4pm today.
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