Easterlies in Christchurch

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Easterlies in Christchurch

Unread post by NZ Thunderstorm Soc »

I thought I would start up a new topic on the ENE winds that tend to spoil Christchurch's weather.
Like how Michael went on about the gales in Auckland, is there someway we can prevent the NE ruining our lives especially the ones that frequent places, and hinder beach goers at beaches like New Brighton beach and Sumner, during the supposedly warmer summer months. Why do we have north-easterlies? Why can they spoil a nice sunny day? Why are they can become fresh and strong?
The NE wind is a strong influence on Christchurch weather, making it much cooler on summer days when the weather could be much warmer. If the wind is fresh or from a more ENE direction, the indicators are evident of a southerly change coming through, later, or the next day.
Enough said.
Anymore contributions to this, most appreciated. :smile:
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Re: Easterlies in Christchurch

Unread post by Thunder »

Move to Mount Somers, nice days with light winds when there is a gusty easterly in Christchurch :D
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Re: Easterlies in Christchurch

Unread post by Richard »

Thunder wrote:Move to Mount Somers, nice days with light winds when there is a gusty easterly in Christchurch :D
Yes either head west John or north past Amberley.
There's a pattern ive notice with the Pegasus Bay onshore wind is when its blowing a straight E in the bay here in the Amuri we get a lighter southerly breeze, but if that onshore wind is more NE it will be NE here as well.
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Re: Easterlies in Christchurch

Unread post by Razor »

Have heard in the past that its partially related to the Cook Strait funnel effect as it fans out into the eastern seaboard but I can't substantiate it. So I'm sceptical on that. However, its clearly a relationship between sea and land and I suspect Banks Peninsula enhances the feature locally

Certainly the curse of the summer here.
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Re: Easterlies in Christchurch

Unread post by TonyT »

NZ Thunderstorm Soc wrote:I thought I would start up a new topic on the ENE winds that tend to spoil Christchurch's weather.
Like how Michael went on about the gales in Auckland, is there someway we can prevent the NE ruining our lives especially the ones that frequent places, and hinder beach goers at beaches like New Brighton beach and Sumner, during the supposedly warmer summer months. Why do we have north-easterlies? Why can they spoil a nice sunny day? Why are they can become fresh and strong?
The NE wind is a strong influence on Christchurch weather, making it much cooler on summer days when the weather could be much warmer. If the wind is fresh or from a more ENE direction, the indicators are evident of a southerly change coming through, later, or the next day.
Enough said.
Anymore contributions to this, most appreciated. :smile:
There is quite a lot known about the Canterbury northeasterlies. The expert is Ian McKendry, who did his Phd thesis on the subject at Canty University back in the 1980s. He is a local fella who is now professor of geography at the University of British Columbia. This paper is a good start:

http://www.metsoc.org.nz/system/files/j ... kendry.pdf

He found there were three types of northeast wind:
1) the true sea breeze, which is more of an easterly across Christchurch, can be east southeast in North Canterbury and south of Banks Peninsula, which is mainly a summer phenomenon.
2) a genuine northeast airstream, which comes along from time to time, and often starts out as a southwest wind across the Plains, but turns northeast once the flow gets strong enough.
3) the lee trough northeasterly which is a combination of outwash from Cook Strait funnelling down the east coast, and air getting "sucked in" to the lee trough which occurs when our usual upper level westerly airflow rises up and over the Southern Alps (and gives us that well known kink in the isobars over the Plains).

Its the lee trough northeasterly which can get quite strong as the pressure gradient builds up over the South Island, leading to increasing westerly wind strength above, but prior the northwest wind breaking through the surface. We sometimes get northwest winds in say Amberley, but its still a lee trough northeasterly from about Woodend southwards to Christchurch. The very hot day in December was a good example too, with Christchurch Airport getting a light northwest wind and reaching 36deg, but the cool easterly still blowing at New Brighton with 18deg there.

The northeasterly is also interesting in that (counter-intuitively) it often begins inland, and spreads towards the coast, rather than the other way around.
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Re: Easterlies in Christchurch

Unread post by Razor »

Thanks Tony! Always a go to for these things round here, cheers :)
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Re: Easterlies in Christchurch

Unread post by Captain Salty »

how far offshore does the true sea breeze get sucked in from?
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Re: Easterlies in Christchurch

Unread post by TonyT »

Captain Salty wrote:how far offshore does the true sea breeze get sucked in from?
I dont know, but I would guess its only about as far as it gets inland, so perhaps 50km?
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Re: Easterlies in Christchurch

Unread post by RWood »

I still recall driving from Central Otago to Ch'ch in Jan 1972 - sunny and a modest 21C or so at Tekapo, plunged into cloud from the top of Burkes Pass onwards, cloud seemed to cover the entire Plains. About 15C at Ch'ch at 6pm with moderate E/ENE. I found maps later which suggested an anticyclone over the country that day but perhaps a suggestion of NW flow starting in the far southwest. Probably a case of return flow through Cook Strait?
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Unread post by melja »

I think the Mackenzie is just to high an altitude for most low cloud and NE winds to make it over the foot hill's. I've seen 28C in tekapo then only 9C in Burke's pass and thick drizzle, very common in summer.
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Re: Easterlies in Christchurch

Unread post by Storm Struck »

More to the question, why are we getting more frequent days of strong NE this summer than that of the past 5 years.
Ive noticed in particular this year it seems to get stronger around 5-6pm, which would indicate the change in air temperatures as the evening rolls in.
The same affect can be seen when warm NW flows are incoming from the Tasman, the NE becomes strong.
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Re: Easterlies in Christchurch

Unread post by Razor »

And right on cue...the sun is back...and so is the dreaded easterly.
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Unread post by melja »

Must be NW tomorrow then I'm guessing
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Re: Easterlies in Christchurch

Unread post by spwill »

I think warmer afternoon temperatures inland will be helping crank up the coastal northeaster.
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Unread post by melja »

Yeah and that 5pm peak is around peak heating inland that Jason mentioned.
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Re: Easterlies in Christchurch

Unread post by TonyT »

Northwest 15 knots and 27 degrees in Amberley from about midday today, still northeast 15 knots and 21 degrees at Christchurch Airport.
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Re: Easterlies in Christchurch

Unread post by Captain Salty »

Up on the Port Hills this evening warm with no real wind, felt NW'ery. Back into the cool easterly at the bottom of the hill.
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Re: Easterlies in Christchurch

Unread post by dogmelon »

You could move inland to escape the easterly but then you get lower night time temperatures. You can't win.
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Re: Easterlies in Christchurch

Unread post by bobbymcd »

Strength of the easterly seabreeze is proportional to differnce in land/se temperature.
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