Darfield Temps

Willoughby · Unread post by **Willoughby** » Sun 13/08/2006 13:14

umm 18 and 16Â°C.. can you verify those temperatures please?

spwill · Unread post by **spwill** » Sun 13/08/2006 13:18

umm 18 and 16Â°C.. can you verify those temperatures please?

Looks like 12-13C down there with negative dewpoints, very dry air.

Dean. · Unread post by **Dean.** » Sun 13/08/2006 13:20

Makes sense to me,Darfield is 25 kms or so inland from ChCh.

Smeagol · Unread post by **Smeagol** » Sun 13/08/2006 13:22

http://weather.selwyn.govt.nz/DRF/

RWood · Unread post by **RWood** » Sun 13/08/2006 13:23

Darfield's temps. are often misquoted or misrepresented (ask GR about Twizel's "heat sink" where temps are reported by many- and lots of other cases for that matter) so I'm skeptical.

In one recent summer a claim was made for an "official" 41 or thereabouts there - it got revised downwards 2 or 3 degrees in due course.

Willoughby · Unread post by **Willoughby** » Sun 13/08/2006 13:27

This page is updated every five minutes from data collected
on the roof of the Darfield Service Centre

Well that's a weather station no no!

Karen may tell us tonight then

RWood · Unread post by **RWood** » Sun 13/08/2006 13:28

In other words - it's bollocks. The max. probably coincided with the best incident angle of the sun on that roof.

Darfield's reputed 41 of a couple of seasons back made it into the preliminary NIWA summaries before it was revised.

spwill · Unread post by **spwill** » Sun 13/08/2006 13:31

Makes sense to me,Darfield is 25 kms or so inland from ChCh.

In early August when the rest of the country is cool you would have to query 18C.

03Stormchaser · Unread post by **03Stormchaser** » Sun 13/08/2006 13:37

Oxford is at 11C if that helps!

RWood · Unread post by **RWood** » Sun 13/08/2006 13:42

Deano wrote:Makes sense to me,Darfield is 25 kms or so inland from ChCh.

The average daily max. in August for the following 5 stations covers a range of only 0.4C (the highest being Waipara and the lowest Chch. Aero):

ASHBURTON COUNCIL
WAIPARA
DARFIELD
CHRISTCHURCH AERO
CHRISTCHURCH GARDENS

03Stormchaser · Unread post by **03Stormchaser** » Sun 13/08/2006 13:48

RWood wrote:
Deano wrote:Makes sense to me,Darfield is 25 kms or so inland from ChCh.

The average daily max. in August for the following 5 stations covers a range of only 0.4C (the highest being Waipara and the lowest Chch. Aero):

ASHBURTON COUNCIL
WAIPARA
DARFIELD
CHRISTCHURCH AERO
CHRISTCHURCH GARDENS

If that was the case wouldnt then Darfields Max temps then be accurate!

Willoughby · Unread post by **Willoughby** » Sun 13/08/2006 13:54

If that was the case wouldnt then Darfields Max temps then be accurate!

I believe there's two stations there, the NIWA station (in guidelines with WMO), and that Selwyn Council station on a roof.

Hey Smeagol, maybe you should advise these people that it isnt the right spot to be sticking temperature and humidity sensors?

03Stormchaser · Unread post by **03Stormchaser** » Sun 13/08/2006 13:57

Foggy Hamilton wrote:
If that was the case wouldnt then Darfields Max temps then be accurate!
I believe there's two stations there, the NIWA station (in guidelines with WMO), and that Selwyn Council station on a roof

ofc

Smeagol · Unread post by **Smeagol** » Sun 13/08/2006 14:02

Foggy Hamilton wrote:
If that was the case wouldnt then Darfields Max temps then be accurate!
I believe there's two stations there, the NIWA station (in guidelines with WMO), and that Selwyn Council station on a roof.

Hey Smeagol, maybe you should advise these people that it isnt the right spot to be sticking temperature and humidity sensors?

Hmm... Will do when I'm back at work as it's only around the road

Flutterbye · Unread post by **Flutterbye** » Sun 13/08/2006 14:06

I see it's down to 11.3Â° now.

Weathermad · Unread post by **Weathermad** » Sun 13/08/2006 16:21

Here are the official maximum temps for the day around canterbury from the MetService...Darfield 'officially' hitting a high of 12 degrees...

Kaikoura : 14
Christchurch : 13
Ashburton : 12
Timaru : 13
Timaru Gardens : 13
Hanmer_Springs : NODATA
Culverden : 12
Amberley : NA
Lyttelton : 13
Darfield : 12
Waipara : 13

Weathermad · Unread post by **Weathermad** » Sun 13/08/2006 16:23

Here is the rest of the country at a glimpse...

Kaitaia : 16
Whangarei : 14
Auckland : 14
Tauranga : 14
Hamilton : 12
Whakatane : 14
Rotorua : 11
Tokoroa : 11
Taupo : 10
Gisborne : 14
New Plymouth : 13
Napier : 15
Hastings : 13
Wanganui : 11
Palmerston North : 12
Levin : 11
Kapiti : 13
Masterton : 13
Wellington : 12
Nelson : 12
Blenheim : 13
Westport : 9
Greymouth : 9
Hokitika : 9
Christchurch : 13
Timaru : 13
Oamaru : 11
Alexandra : 8
Queenstown : 7
Dunedin : 6
Invercargill : 9
Bay of Islands : 14
Murchison : NA
Kaikoura : 14
Culverden : 12
Amberley : NA
Rangiora : NA
Ashburton : 12
Darfield : 12
Lyttelton : 13
Hanmer_Springs : NODATA
Methven : NA
Hororata : NA
Timaru Gardens : 13
Milford Sound : 10
Haast : 11
Gore : 6
Dunedin Airport : 7
Manapouri : 7
Totaranui : NA
Lake_Rotoiti : NODATA
Molesworth : NA
Kenepuru : NA

Todays highest temperature was 16 at Kaitaia

Todays lowest maximum temperature was 4 at Waiouru

squid · Unread post by **squid** » Sun 13/08/2006 16:32

where did this come from

TonyT · Unread post by **TonyT** » Sun 13/08/2006 16:38

If you check the data from http://nrfa.fire.org.nz it shows a temp of 12.4 at 1pm for Darfield, whereas the graph from the Selwyn District Council site shows around 17-18 deg at the same time.

As has been pointed out, the Council weather station is on the roof, whereas the NRFA station is the one you can see from SH73 as you drive into Darfield from Chch. It is a conventional AWS with the temperature and humidity sensors at the right height (1.2m) in a metal screen. The location is rural, and I would imagine fairly representative of a broad area of the Plains around.

So, this anomaly is a classic illustration of the problems of sensor exposure contaminating weather data. [Where is Gary when you need him? ] It should serve as an important lesson for all of us who set up and operate weather stations, and make the data available to others.

The issue with the 41deg was that at those levels of warmth the electronic sensor in the small metal screen without forced ventilation over reads compared to the old mercury in glass thermometer in a Stevenson screen. There is a formula which can be applied to correct the electronic reading to be comparable, and thats why that reading was revised downwards. It wasnt because the exposure of the current sensor is anything less than optimal.

Oh, and Weathermad, that reading is no more official than any other, it just happens to come from a better exposed sensor.

RWood · Unread post by **RWood** » Sun 13/08/2006 17:08

TonyT wrote:
So, this anomaly is a classic illustration of the problems of sensor exposure contaminating weather data. [Where is Gary when you need him? ]

Where indeed???

Interesting info. re the corrections for electronic sensors.

Weathermad · Unread post by **Weathermad** » Sun 13/08/2006 17:30

MetService provide the maximum daily temps for broadcast on radio and email them to me and they come through at around 4.15 each day(which suggests that the max temps are up to 4pm and in summer that could possibly be a little misleading as maximum temps can be after 4pm...any thoughts on this?)

These sites are the 'official' MetService sites and are the temperatures that are shown on TV in the evenings

Whats also interesting is how a few sites seem to provide little or no data on a daily basis

NZ Thunderstorm Soc · Sun 13/08/2006 17:56

Weathermad wrote:MetService provide the maximum daily temps for broadcast on radio and email them to me and they come through at around 4.15 each day(which suggests that the max temps are up to 4pm and in summer that could possibly be a little misleading as maximum temps can be after 4pm...any thoughts on this?)

Dunedin had problems with this years ago when the guy on the TV3 weather would say that the current reading in the town was ...say 18C, when recently he mentioned the fact on the maximum temperature chart that the maximum was only 16C ..

JohnGaul
NZTS

TonyT · Unread post by **TonyT** » Sun 13/08/2006 18:42

Weathermad wrote:These sites are the 'official' MetService sites

They are the sites Metservice obtain data from. In the case of Darfield the site is owned and operated by the NRFA. There is nothing official or otherwise about them.

Weathermad · Unread post by **Weathermad** » Sun 13/08/2006 19:05

The so called sites that MetService use are 'official' in their eyes

I have yet to see 'other' daily maximums issued nationwide

TonyT · Unread post by **TonyT** » Sun 13/08/2006 19:24

Weathermad wrote:I have yet to see 'other' daily maximums issued nationwide

Isnt that what this whole thread is about? There are plenty of non-MetService temps out there for people to see, including the ones on the roof of the Council building in Darfield.

My point is that it doesnt matter whether a site is considered 'official' or not, what matters is that the sensors are installed and operated in accordance with standards which, based on experience, produce consistent and repeatable data. There are plenty of sites around that meet that criteria which are not owned by Metservice. Whether you feel they qualify as 'official' is up to you.

I now take off my cloak and mask, and reveal myself to the group as Gary in disguise...