Gales and Storms - 23rd -25th March

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David
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Re: General March Weather

Unread post by David »

Looks like some very decent instability for N/W facing areas Thursday afternoon/evening. Lifted index GFS forecast for 7pm Thursday:
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General March Weather

Unread post by jamie »

Very quiet on here of late.

I'm hoping/expecting at least 20mm from this system. Getting quite dry again here. 50mm would be great and doesn't seem out of the question if we can catch a downpour. What are others expecting?
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Re: General March Weather

Unread post by NZstorm »

jamie wrote:Very quiet on here of late.

I'm hoping/expecting at least 20mm from this system. Getting quite dry again here. 50mm would be great and doesn't seem out of the question if we can catch a downpour. What are others expecting?
Yes, 20mm atleast. The rainfall totals will get a boost from a squally downpour along the frontal boundary. Can't rule out thunder.
Ukmet and gfs different on timing.

Over Canterbury tomorrow afternoon, the southerly front may be able to trigger a slightly elevated thunderstorm.
Last edited by NZstorm on Wed 23/03/2016 07:21, edited 1 time in total.
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Re: General March Weather

Unread post by NZstorm »

gfs 48hr total for event
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Re: General March Weather

Unread post by spwill »

March has been a dry month so far, incoming system looks good for some downpours here tomorrow morning but as always they can be hit and miss.
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Re: General March Weather

Unread post by jamie »

Getting windy here now. Being an E wind the trees are not used to it. Max gust 55km but still building
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Tornado Tim
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Re: General March Weather

Unread post by Tornado Tim »

GFS prognostic indicating a decent upper level shortwave will pass through the upper half of the North Island Thursday afternoon.
Good upper level dynamics forecast, with the shortwave on the lee edge of the upper jet causing upper winds to narrow and accelerate which should create good buoyancy on any convection that occurs tomorrow PM.
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Re: General March Weather

Unread post by Bradley »

A massive downgrade for central Canterbury rainfall wise - gone from 30-40mm to now 5-10mm - hopefully it will be like last weeks event and we get 2-3 times more than forecast!!
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Re: General March Weather

Unread post by shovelopikis »

Big gusts on and off here in central plateau
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Re: General March Weather

Unread post by jamie »

Just had a whopper gust come thru but it clearly missed the cowshed where the anemometer is. Would think it would have been around 80km/hr
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Re: General March Weather

Unread post by Richard »

Yet there's not a leaf moving on the trees outside here
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Re: General March Weather

Unread post by spike_01 »

Calm and humid in Wellington. .

I would have thought there would be a new thread for this 24 hour event..
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Gales and Storms - 23rd -25th March

Unread post by Tornado Tim »

This event now deserves its own thread: Mod Note: Moved relevant posts from the General March Thread to here.

Metservice T-storm Outlook (23rd AM update):
Metservice wrote: Issued at: 8:38am Wednesday 23 Mar 2016

A series of lows and associated fronts over the Tasman Sea are expected to approach the country today, preceded by a strong, moist northeast flow.

Heavy rain and northeast gales are forecast for northern and western parts of New Zealand (refer to the latest Severe Weather Warning and Watch for more details).

There is a broad low risk of embedded thunderstorms within this rainband over western parts of the South Island from northwest Nelson down to Fiordland from this afternoon, with possible localised downpours. However, the risk of thunderstorms is considered moderate over Southern Westland and northern Fiordland late this afternoon and evening. Any thunderstorms that eventuate are likely to enhance rainfall rates up to 25mm per hour or possibly more.

There is also a low risk of one or two thunderstorms with heavy rain over northern parts of Northland today spreading down to Auckland this evening.However, this risk of thunderstorms increases to moderate over northern Northland tonight, with the potential for some localised intense rainfalls up to 25mm per hour or possibly more.

No thunderstorms or significant convection expected elsewhere.
756c-153a20eeb00-153a3588200-1539fd5a412.0.png
A low is forecast to cross central New Zealand Thursday morning, while an associated front moves onto the North Island. A strong, very moist northeast flow ahead of the front is forecast to bring heavy rain and gales to northern and western parts of New Zealand (refer to the latest Severe Weather Warning and Watch for more details).

There is a moderate risk of SEVERE thunderstorms over northern Northland before dawn and from Taranaki and Bay of Plenty northwards during Thursday morning, as indicated on the chart. These SEVERE thunderstorms could produce localised downpours of 25 to 40mm per hour or possibly more for a time. Rainfall of this intensity can cause surface and/or flash flooding as well as slips and hazardous driving conditions.

There is also a moderate risk of localised downpours with rainfall rates of 25 to 40mm per hour within the Severe Weather Warning area from northern Marlborough, Nelson, Buller down to northern Westland, mainly before dawn.

There is a low risk of embedded thunderstorms with localised downpours over a broader area extending across remaining northern and western areas, as indicated on the chart.

No thunderstorms or significant convection expected elsewhere.
756c-153a20eeb00-153a5ebb000-153a059012e.0 (1).png
spike_01 wrote: I would have thought there would be a new thread for this 24 hour event..
Done :)
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Re: Gales and Storms - 23rd -25th March

Unread post by spike_01 »

Haha here we are . :lol:

Looks to be a very interesting 24 hours..
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Re: Gales and Storms - 23rd -25th March

Unread post by littleheaven »

Blustery here in Glenfield - my anemometer is too sheltered to capture correct wind speeds but the house has shaken a few times. Rain has been thin and somewhat sideways. My gauge is showing no rainfall - seems to be clear of leaves and properly connected, so maybe the horizontal nature of the rain means it's being blocked by the house and is missing the little catcher.
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Re: Gales and Storms - 23rd -25th March

Unread post by Orion »

From Auckland region Civil Defence: http://cdem.co/viewer.jsp?token=l1ucyHUQ -
"MetService has issued a severe weather watch for heavy rain in Auckland with the risk period being early tomorrow morning with downpours of 25 to 40 mm/hr. MetService has also issued a warning for severe wind gusts of 120 to 130km/hr. Winds will build from 3pm today, gusts over 100km/hr are possible until 11am tomorrow morning."
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Re: Gales and Storms - 23rd -25th March

Unread post by Manukau heads obs »

currently most of the rain is out to the west of the NI
and the sub tropical low is moving more S of SSE ?
and alot of the energy/cloud has now formed along the jet stream to the south of the low center...
i.e it looks like Auckland/waikato/coromandel might miss most of the rain
but taranaki and the top of the south island are in the firing line?
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Re: Gales and Storms - 23rd -25th March

Unread post by spwill »

Some short duration heavy rainfall for us with the front tomorrow morning.
Some big Cbs/thunderstorms near Northland this evening, showing up well on the lightning tracker/radar
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Re: Gales and Storms - 23rd -25th March

Unread post by mikestormchaser »

SW change I see tomorrow with what I'd say a low risk of a thunderstorm in Canterbury in the afternoon. Quite a strong change to by the looks on the maps so southerly buster type storm if any.
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Gales and Storms - 23rd -25th March

Unread post by jamie »

Manukau heads obs wrote:currently most of the rain is out to the west of the NI
and the sub tropical low is moving more S of SSE ?
and alot of the energy/cloud has now formed along the jet stream to the south of the low center...
i.e it looks like Auckland/waikato/coromandel might miss most of the rain
but taranaki and the top of the south island are in the firing line?
I've been thinking along those lines most of today.
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Re: Gales and Storms - 23rd -25th March

Unread post by NZ Thunderstorm Soc »

Could get some hail in the showers tomorrow with the southerly change, sadly no chance on any lightning to form to make the sound of thunder, which we have so much of missed in this great El Nino summer :rolleyes: [-X
.........but there is the risk of some 'violent drizzle' with the change >_<
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Re: Gales and Storms - 23rd -25th March

Unread post by Manukau heads obs »

I see its been gusting to 74 kts and averaging 63 kts (that's Hurricane force) at Cape Reinga
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Re: Gales and Storms - 23rd -25th March

Unread post by Tornado Tim »

Storms continuing to fire, but Lightning activity much weaker than previously.

New lot of convection of firing under the Jet and the previous lot of convection and assoc storms is under a exit region of the jet where the upper winds starts to fan out.

More convection and storms will flare up on that jet entrance later on tonight and tomorrow morning.
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Re: Gales and Storms - 23rd -25th March

Unread post by cbm »

Manukau heads obs wrote:I see its been gusting to 74 kts and averaging 63 kts (that's Hurricane force) at Cape Reinga
Must be some significant site specific enhancement happening there as Kaitaia only showing 39kmph, similar to other upper North island urban stations.
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Re: Gales and Storms - 23rd -25th March

Unread post by NZstorm »

cbm wrote:
Manukau heads obs wrote:I see its been gusting to 74 kts and averaging 63 kts (that's Hurricane force) at Cape Reinga
Must be some significant site specific enhancement happening there as Kaitaia only showing 39kmph, similar to other upper North island urban stations.

I think when you look at wind events you have ignore the elevated coastal headland sites as they give a distorted view.
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