Wellington / Kapiti floods 14/15 May

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Razor
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Wellington / Kapiti floods 14/15 May

Unread post by Razor »

Talking to my sister in Plimmerton, things seem pretty insane round there at the moment. Pictures in the media of some pretty severe floods, and another deluge due later today/ tonight for some areas.

The weather gods in Welly are certainly celebrating the reinstallation of the zephryometer wind wand

Hope all well with our Wellington correspondents
Last edited by Razor on Thu 14/05/2015 13:33, edited 1 time in total.
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Re: Wellington / Kapiti floods 14/15 May

Unread post by Razor »

Its a shame this forum doesn't have more Wellington folk. Schools being closed left right and center, sounds quite chaotic

If this was a ChCh or Jaffabowl event the forum would be going nuts
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Re: Wellington / Kapiti floods 14/15 May

Unread post by BeaconHill »

Certainly has been a significant event north of the city. The rain radar since midnight showed a "river" of rain focussed on the Mana to Paraparaumu area, and that’s where the flooding is by far the worst. My parents are right on the beach at Waikanae, and had had 107mm since midnight, and yet the rain was heavier to the south of them from what they have heard.

In town itself, it has been steady rain since midnight (30mm according to Metservice to midday), but nothing exceptional. It looks like we just missed a heavy band of rain over the Lower Hutt area between 11-12 (Metservice tweeted 48mm rain recorded in 1hr period vs 11mm in town in 10am-12 period.) Some BIG rumbles of thunder to the north of the CBD during that time.

A few more heavy showers incoming on the radar by the looks too in the next hour or 2. Any moderately significant showers are going to cause more problems that’s for sure!
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Re: Wellington / Kapiti floods 14/15 May

Unread post by David »

Paraparaumu has had about 120mm since midnight, impressive!
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Re: Wellington / Kapiti floods 14/15 May

Unread post by spike_01 »

Pretty wet in Ngaio.. Thunder, Lightening..
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Re: Wellington / Kapiti floods 14/15 May

Unread post by Manukau heads obs »

will be losts more rain for wellington area over the next 24 hours by the look of the sat image!
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Re: Wellington / Kapiti floods 14/15 May

Unread post by kiwisk8er »

The rain has been crazy. In the last 24 hours there's been 93.9 mm of rain at our place in Tawa. There's been thunder and lightning off and on during the day.

The Tawa main road got flooded and most of the businesses are cleaning up the mess. At least 4 schools in the valley got closed due to flooding. Our basement got flooded, along with our front and back yards. The porirua stream which is usually half a meter across is currently at 4 - 5 meters wide and roaring on it's way to the sea.
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Re: Wellington / Kapiti floods 14/15 May

Unread post by Razor »

According to metservice site, Lower Hutt had 63mm just in one 2 hour period alone after lunch. Now that is extreme for anywhere, let along an urban environment.

Wow.
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Re: Wellington / Kapiti floods 14/15 May

Unread post by RWood »

Not all that much rain in W'gton city, but its drainage systems in various parts are antiquated and not up to the job. Imagine the chaos if the city got 109mm in an hour (Leigh, May 2001) or 107mm in an hour (Whenuapai, Feb 1966 where 10.23" fell in on the 16th)
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Re: Wellington / Kapiti floods 14/15 May

Unread post by Nev »

Razor wrote:According to metservice site, Lower Hutt had 63mm just in one 2 hour period alone after lunch. Now that is extreme for anywhere, let along an urban environment.

Wow.
Think you mean before lunch. But yes, (as BeaconHill mentioned earlier) 3/4 of that (48mm) fell in the hour to midday. Also 101mm of today's rainfall at Paraparaumu Aero fell in the 8 hours 7 hours to 10am.
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Re: Wellington / Kapiti floods 14/15 May

Unread post by Manukau heads obs »

48mm in an hour is right up there :)
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Re: Wellington / Kapiti floods 14/15 May

Unread post by Richard »

Amazing watching the flooding in the Wellington area on TV tonight and huge rainfalls on the SI West Coast over the last week while here we are still in severe drought :rolleyes:
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Re: Wellington / Kapiti floods 14/15 May

Unread post by Orion »

Horrible event, and now a report that someone has perished in the floods.
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Re: Wellington / Kapiti floods 14/15 May

Unread post by Razor »

Orion wrote:Horrible event, and now a report that someone has perished in the floods.
Terrible news, an elderly man washed away from his car by the sound of things
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Re: Wellington / Kapiti floods 14/15 May

Unread post by Wildland »

Tawa Weather recorded 96 mm yesterday, the wettest day recorded during ten years of operation.
Previous wettest day was 25 May 2010 when 80 mm was recorded.

Peak rain rate calculated by Weather Display yesterday was 1.5 mm/min (92.3 mm/hr) at 13:47. Rain was intense at times but didn't exceed the short deluge calculated at 10 mm/min on 15 May 2006.

Looking at those dates, it seems that May might be a month of weather extremes for Tawa. :-k
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Re: Wellington / Kapiti floods 14/15 May

Unread post by Wildland »

On reflection that peak rain rate of 10 mm/min for 15 May 2006 looks a bit odd. Extreme
There may be a glitch in my database. :crazy:
I'll have to go back through records to confirm it or correct it.
It was timed at 22:24 - too late for me to be doing crazy things with a hose...
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Re: Wellington / Kapiti floods 14/15 May

Unread post by Manukau heads obs »

Those are instantaneous rain rates
based on the time bbetween tips
but you can set to use the console rain rate if Davis station :)
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Re: Wellington / Kapiti floods 14/15 May

Unread post by kiwisk8er »

Our weather station is in Linden, I'm often checking your weather station to compare :-)
Wildland wrote:Tawa Weather recorded 96 mm yesterday, the wettest day recorded during ten years of operation.
Previous wettest day was 25 May 2010 when 80 mm was recorded.

Peak rain rate calculated by Weather Display yesterday was 1.5 mm/min (92.3 mm/hr) at 13:47. Rain was intense at times but didn't exceed the short deluge calculated at 10 mm/min on 15 May 2006.

Looking at those dates, it seems that May might be a month of weather extremes for Tawa. :-k
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Re: Wellington / Kapiti floods 14/15 May

Unread post by Wildland »

Manukau heads obs wrote:Those are instantaneous rain rates
based on the time bbetween tips
but you can set to use the console rain rate if Davis station :)
After posting I was a bit concerned about the extreme rate, so decided to check.
On 15 May 2006 we had a southerly gale with showers in the morning and during the evening.
18 mm was recorded for the day, so the intense downpour is within reason. It was a wet month with 109 mm recorded.
I'll let it stand, but wanted to make sure.
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Re: Wellington / Kapiti floods 14/15 May

Unread post by Wildland »

kiwisk8er wrote:Our weather station is in Linden, I'm often checking your weather station to compare :-)
Ditto :D

I checked out the flooded area at Collins Ave today and talked to some residents whose properties back onto the Porirua Stream near Duncan Park. Actually we shouted at each other across the noise of the stream! The damage to their streamside gardens is a shock, and the high water level indicates how close they were to having water through their houses as well. We were lucky that the rain eased off when it did.
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Re: Wellington / Kapiti floods 14/15 May

Unread post by RWood »

For the city itself the rain was heavy but not exceptional - a 48mm reading, with 34mm a couple of days earlier.
W'gton monthly record not likely to be threatened - that was part of a bizarre sequence in 1942 - 301mm May (wettest and cloudiest May on record), 14mm June (record low), 258mm July (and near-record low sun).
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Re: Wellington / Kapiti floods 14/15 May

Unread post by kiwisk8er »

You should check out the Tawa Volunteer Fire Services facebook page, lots of photos from the day.

We live on the hill above the railway line and the stream on Handyside Street. On Thursday I could hear the Porirua stream roaring from our kitchen inside.
Wildland wrote:
kiwisk8er wrote:Our weather station is in Linden, I'm often checking your weather station to compare :-)
Ditto :D

I checked out the flooded area at Collins Ave today and talked to some residents whose properties back onto the Porirua Stream near Duncan Park. Actually we shouted at each other across the noise of the stream! The damage to their streamside gardens is a shock, and the high water level indicates how close they were to having water through their houses as well. We were lucky that the rain eased off when it did.
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Re: Wellington / Kapiti floods 14/15 May

Unread post by Wildland »

The Greater Wellington Regional Council issued a media release today containing rainfall and river flow summaries.

Here's a few items relevant to Thursday's event:

“The Porirua Stream peaked at a flow rate of 66 cubic metres per second which was the third largest flow seen there since the floods of 1976, and the largest since 1980. It ranks as the largest flood to have occurred since the Seton Nossiter and Stebbings flood detention dams were constructed in the upper catchment.”

"The Waikanae River peaked at a flow 270 cubic metres per second above SH1. This was the 3rd largest flow recorded since 1975 – only January 2005 and October 1998 were larger. A flow in the river of this size is expected once every 13 years.”

“In the Hutt Valley, 42mm of rain was recorded in Avalon in just one-hour – that’s estimated to be in excess of a 1-in-50 year event.”

The report contains rainfall data for selected sites:

MacKay's Crossing 145 mm
Battle Hill (Porirua) 144 mm
Tawa Pool 115 mm
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