Heavy Rainfall in Nelson Region

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Tim S
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Heavy Rainfall in Nelson Region

Unread post by Tim S »

I couldn't find a valid open topic for this so I thought I would start a new one, apoligies in advance if there is one hiding somewhere. :)

I noticed Nelson had around 100mm in the 24hrs to 9am this morning! the metservice site says 93mm fell to 9am. Is that a fairly unusaully high fall for them or are falls in the order of 100mm fairly common for that area at this time of the year?

I was following this event quite closely and noticed all the heavy rainfall and tstorm warnings put out last night so I knew it was going to be a goodie, but thought the heaviest rain would be on the west coast of the south island, going by the metservice map for rain to 9am this morning looks as though the area around Nelson between the Richmond ranges and Takaka Hill got the heaviest falls. :? Must have been due to the wind direction I guess?
Snowlover
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Unread post by Snowlover »

My Aunty just emailed me she is in Stoke. Fire bridgage came to pump out water from their garage and sheds. They have also just been interviewed by 3 news for tonight. Local school is awash and insurance company is coming around it sounds kind of bad up there!!!!
RWood
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Unread post by RWood »

Yes, inflows from the N/NE can produce very heavy rains. Nelson city only averages about 990 mm/year but occasionally gets very heavy falls. The Takaka area in Golden Bay has averages ranging from 1600+ mm at Pohara beach to about 2500+ mm in nearby hills and very heavy falls of up to 300mm in a day have been recorded (259mm at Kotinga on 11/11/1990 of a monthly total of 488mm). Noteworthy daily falls of over 100mm occurred at Nelson in January 1985 & January 1986 - January is normally rather dry there - these were both very warm months.
RWood
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Unread post by RWood »

Snowlover wrote:My Aunty just emailed me she is in Stoke. Fire bridgage came to pump out water from their garage and sheds. They have also just been interviewed by 3 news for tonight. Local school is awash and insurance company is coming around it sounds kind of bad up there!!!!
I see from pictures that there's been some slippage on the Panorama Heights subdivision - more shoddy work by developers?
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Unread post by RWood »

Update: 98mm recorded somewhere in Nelson. Not close to a record, but a lot of it fell in just a few hours. Also some very heavy falls near New Plymouth, don't have any totals yet. Taranaki (except parts of its south) is no stranger to very heavy falls from time to time, even away from the mountain. Here's some instances:

24/2/71 11.41" at N Plymouth, 12.94" at airport (both 1-day records)
16.05" at Stratford Mountain House (31.3" in 2 days)

10/3/90 (approx.) 338mm at Lepperton, 275mm at Inglewood.

The wettest location of North Egmont wasn't recording data in 1971, otherwise it would almost certainly have topped the quoted values.
Tim S
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Unread post by Tim S »

Cheers for that info RWood, I notice there are usaully two rainfall figures for Nelson, I know one site is at the airport is the other at Stoke?

I notice the average rainfall for Nelson (Airport?) for May is 77mm, so 93-98mm in one day is a pretty good fall by any standards.

I have actually been getting some info on Nelson's climate as I am looking at moving there, though I think after todays event I will stay away from new housing developments where they have completely removed all trees and such! ;)
RWood
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Unread post by RWood »

Nelson Aero: mean annual sunshine 1930-2006 is 2435 hrs (a bit higher over the last decade but there have been a few site changes or adjustments over the period). Mean rainfall 1941-2006 is 978 mm (same comments); 30-year normal 1971-2000 is 943 mm. Mean number of rain days with 1.0mm or more is 95.

The second site quoted is probably at nearby Appleby. Rainfall in the hill catchments to the S and SE of the town is considerably higher.

We investigated the place fairly closely a few years back with a view to moving there one day. I wouldn't go near the type of subdivision you described - developers get away with far too much. Note that there is a marked changed in the climate as you leave the town to the NE (towards the Marlb. sounds) - a few kms down the road after leaving Tasman Bay it's significantly damper and cloudier.
Tim S
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Unread post by Tim S »

Seems developers over here are the same as over in NZ, they love removing every single tree when they develop land. Its not a major problem here as we dont have very hilly terrain (or heavy rain for that matter :( ) though I imagine when you have topography like Nelson its just asking for trouble taking out all the land anchoring trees.

Were there any reports of the river ( I forget its name) that runs through Nelson flooding? I noticed some house were fairly close to that when I was there at the end of last year.
RWood
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Unread post by RWood »

You mean the Maitai river. Didn't hear anything, it usually figures significantly in heavy rain events there. In both January 1985 (particularly) and January 1986 it ran pretty high after daily totals well over 100mm. The Maitai Valley catchment gets about 1540mm per year. My preference for living zones in Nelson would be on older gently sloping parts (not the shaded bits on the wrong sides of the main hills), some flat areas near the water or up on hilltops around Princes Drive and the like.
Tim S
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Unread post by Tim S »

Ahh yeah of course the Maitai, I guess that isnt too bad in heavy rain events due to the fact the Matai Dam controls the flow a fair bit? Unless of course its full which I wouldnt imagine it would be considering how dry it was in that region in the few months at the start of the year. I remembering hearing they had around 30 days in succesion without rain back at the start of the year.

Yeah Princess drive is one of the areas we've been looking at, when I was there I stayed down a bit from there on the Port Hills side, lovely area there but house prices on that side are astromonical.
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Unread post by RWood »

Yes, dam should be OK most of the time. Dry starts are not too uncommon but the longterm rain records for the airport (back to 1941) have the driest month averaging about 68mm so it's not too bad.

They do pay rather a lot for the views across Tasman Bay up on those slopes.
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