NZ Weather Forum

2.4 C colder than the last 8 years here!
http://www.weather-display.com/windy/gb ... taout.html

drier than normal overall too for here

This June has been a much cloudier, colder and drier june than usual. Interestingly earlier i noticed there is still water logged paddocks which surprised me as there hasnt been any decent rain here for a bit. However, i think due to lack of sun and the prodominantly cloudy, dry days have not allowed for any real drying to occur. Infact this june was 2 degrees colder overall and in comparison to June 2008 (last year) WAY drier. June 2008 saw 103.4mm where as this June just 26.8. However, a SWer has been the dominant wind here in Christchurch with slightly calmer conditions than last June with the Northeasterly with a slightly greater wind mean for the month.

From my place,
mean temp=9.9° (mean low 5.7°, mean high 14.1°), max 18.4° and min -1.0°
total rain = 158mm, year so far = 535mm

Definitely felt colder than normal.

Extract from http://wx-matangi.dyndns.org/Current_We ... eekrep.htm
Matangi Weather:
Average temperature = 7.6°C
Average humidity = 91%
Average dewpoint = 6.1°C
Average barometer = 1016.5 mb
Average windspeed = 4.0 km/h
Average gustspeed = 6.3 km/h
Average direction = 176° ( S )
Rainfall for month = 114.8 mm
Rainfall for year = 521.6 mm

June 2009 Summary
Henderson, Auckland. S36.86962 E174.62065 41m ASL
Maxiumum Temperature: 20.2° Thursday 11-June-09
Lowest Maximum: 11.6° Thursday 18-June-09
Minimum Temperature: 0.0° Friday 05-June-09
Highest Minimum: 13.7° Thursday 11-June-09
Total Rainfall: 142.2 mm
Days with Rain: 16 out of 30 days
Most Rain: 20.0 mm Monday 01-June-09
Highest Pressure: 1034.0 mb Thursday 04-June-09
Lowest Pressure: 0985.8 mb Monday 29-June-09

Yes, I'm picking a cold June for northern New Zealand, especially with those frosts in Northland.
Cold here but not that cold, I suppose. I can't depend on records as my readings here only go back 2 years.

JohnGaul
NZThS

Looking at Climate Explorer's anomaly maps for MTD, I'm picking the coldest June for NZ since 1972 (but that one was more universally sunny). Large areas with a deficit of 1.5C or more.

NIWAs official summary is out:

http://www.infonews.co.nz/news.cfm?l=1&t=0&id=38982

But I can't find it on their website.
http://www.niwa.co.nz/our-science/clima ... msum-09-06

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It contains this rather curious comment:

"The highest temperature during June 2009 was 24.5 °C recorded at Henderson, Auckland, on the 29th (not a June maximum temperature record at this site)"

That sounds dodgy. 24.5C in Henderson when Auckland itself reached about 13C? AND it's not a record? Something fishy about that.

That Henderson value can't be right. That report is preliminary, and the website one can take up to a wwek later to appear. Irritatingly, they have quoted Wellington Aero instead of Kelburn for rainfall & temperature, so I am going to point this out to them - can't do comparisons meanwhile. But if the deficit of 1.4C is repeated at Kelburn it does make it by a very narrow margin the coldest June there since 1972, which however is much lower still.

The national average deficit of 0.7C sounds a bit small to me, and not in line with ther general comments.

I am going to query both these points for clarification.

Yes, the Henderson ARC site only recorded a T-max of 15.5°C on the 29th (highest T-max was 19.3°C on the 13th).

No problem with the pdf link btw?

Confirmed that the report quoted Wellington Aero, this will be fixed shortly. The seeming anomaly in the national temperature value is because that is calculated from long-term means for a small set of stations, whereas the individual station values in the report summary relate to current 30-year means, which are of course higher. The national value of 7.5C was actually beaten by 7.4C in 2006, but all other June values since 1972 are at least 7.6C (June 1972 was 6.8C, have to go back to 1941 (6.6C) to get a colder value still).

June 2006 was 1.2C below normal nationally from what I recall, so last month should be 1.1C below, rather than -0.7C.

If you look at the report in the archive, that's quoted relative to the 1971-2000 average, which is 0.3C above the longterm mean used in the current report. [June 2006 is quoted as 7.4C in the temp. series and 7.3C in the archive, a rounding issue explaining the other 0.1C of discrepancy].

So using the rather restricted criteria (which will be reviewed this year I understand) for assessing the national average, June 2006 was slightly cooler than this one, which surprised me slightly. NIWA should make the comparison standards clearer in their reports.

Checked the figures for Mangere (Akld). This June's average T-max should be 12.7°C (NIWA shows 13.6°C) and the average T-min should be 5.7°C (NIWA shows 6.1°C). That gives a mean-temp of 9.2°C, whereas NIWA's summary says 10°C. Not sure what criteria they are using, but even 10°C should still be a lot more than just 0.7°C below normal (sounds more like July).

Monthly summary for Horsham Downs. Was very cold and calm

Average temperature 6.9 °C
Average humidity 88 %
Average dewpoint 4.9 °C
Average barometer 1017.3 mb
Average windspeed 9 kmh
Average gustspeed 11 kmh
Average direction 200 ° (SSW)
Rainfall for month 122.0 mm
Rainfall for year 541.0 mm
-----------------------------------------------------------
Maximum rain per minute 0.8 mm on day 28 at time 19:59
Maximum temperature 17.2 °C on day 10 at time 14:05
Minimum temperature -5.4 °C on day 18 at time 07:54
Maximum humidity 100 % on day 28 at time 11:49
Minimum humidity 51 % on day 07 at time 14:26
Maximum pressure 1034.2 mb on day 03 at time 10:38
Minimum pressure 989.6 mb on day 28 at time 02:04
Maximum windspeed 46.3 kmh from 250° on day 16 at time 13:44
Maximum gust speed 57.4 kmh from 250° on day 16 at time 13:44
Maximum heat index 17.2 °C on day 10 at time 14:05

You were colder than me Jamie.

Nev wrote:Checked the figures for Mangere (Akld). This June's average T-max should be 12.7°C (NIWA shows 13.6°C) and the average T-min should be 5.7°C (NIWA shows 6.1°C). That gives a mean-temp of 9.2°C, whereas NIWA's summary says 10°C. Not sure what criteria they are using, but even 10°C should still be a lot more than just 0.7°C below normal (sounds more like July).

Is that the Mangere EWS given in the monthly stats. tables? - you could check with NIWA. I re-emphasise (for the national value) that the 0.7C is relative to an average which is at least 0.4C cooler than the 1971-2000 equivalent.

RWood wrote:Is that the Mangere EWS given in the monthly stats. tables?

Yes, but oops sorry, I overlooked the fact that there is 2 days of data missing at the Mangere EWS site for this June, so NIWA's monthly stat-tables showing an average T-max of 13.6°C, an average T-min of 6.1°C and an average T-mean of 9.8°C is more or less correct. The latter though is probably more like 9.7°C, as those missing days were well below the average. I suspect that NIWA's mean-temp of 10.0°C in this June's summary is therefore from Akld Aero rather than Mangere.

RWood wrote:I re-emphasise (for the national value) that the 0.7C is relative to an average which is at least 0.4C cooler than the 1971-2000 equivalent.

Yes, but as far as both Mangere and Akld Aero go (which both only have roughly a 50 year history), the generally warmer temps this century balance out those earlier cooler temps, bringing them more or less on par with the 1971-2000 average. However, the Mangere site did close in 1998, then reopened in 2002 (as the EWS), so a 1971-2000 average wouldn't necessarily be an accurate representation. Btw, the site has shifted slightly a few times, but has always been adjacent to the old wastewater treatment plant, so can't see that as being an issue.

Still, there is no way that the long-term mean-temp for June is 10.7°C for either Mangere or Akld Aero. Three years of missing data aside, Mangere's long-term June average (1960-2009) should be about 11.6°C (virtually the same as Akld Aero). Therefore, Mangere's mean-temp for this June should be at least 1.8°C below the long-term average and Akld Aero's about 1.6°C below both the long-term and the 1971-2000 average.

Nev, if you go to the page indicated below in Climate Explorer {you should be in the "national" section} and select the MTD chart (20090701) for mean temperatures, the chart indicates that Mangere and Auckland Aero would be at least 1.5C below average (which here will be the 1971-2000 average), in fact on the borderline with an area 2.0C or more below average. You could ask Andrew Tait about this, or wait until the statistics PDF comes out in a few weeks - it lists Mangere EWS and Auckland Aero. I also notice that they still haven't replaced the Wellington Aero data with Kelburn data in the "main centres" part of the report.

https://secure.niwa.co.nz/climate-explorer/home.do

However the 0.7C for the "national average", which relates to the NZ temperature series calculated from a set of 7 indicator stations, is not necessarily "wrong". If you imagine subtracting about 0.4C from the deficits indicated on the chart for the whole of NZ and allow for a variability of say another 0.2C because of the limited geographic coverage, it could be right.

Edit: the 30-year means for June I have are 12.4C for Albert Park and 11.6C for Auckland Aero and Owairaka, rechecked them in the Cliflo database - nothing quoted for Mangere beyond 1951-80.

Updating the Kelburn data (still not on the website) - mean June temp. was 8.3C, the lowest since 1976 when it was 8.2C. Rainfall was 75mm, not much more than half the average, though the number of raindays was probably at least average. The May-June combination was the coolest since 1959.

Thanks for link(s) RWood. Surprised that the national average temp is calculated from only 7 indicator stations. Seems very limited. The national average June temp being just 0.7°C below the norm still sounds a little dubious though.

Just to clarify, I was only questioning Akld temp stats in NIWA's June summary, also showing just 0.7°C below average, which is obviously wrong.

However, I'm a little perplexed by some of the other main centres as well. The Dunedin mean-temp appears to be taken from Dunedin Aero (5.2°C), rather than Musselburgh (6.6°C) and Hamilton appears to be taken from the Hamilton Aws (7.2°C), rather than Ruakura (7.1°C). Haven't checked to see how accurately they relate long-term averages, but wouldn't be surprised if they're out as well.

Given all the other discrepancies (did you query the highest June temp being 24.5°C recorded at Henderson on the 29th btw?), it does make one wonder just how much of a shambles the rest of the preliminary summary is?

Perhaps Jim Salinger (now an honorary research fellow at Akld Uni and president of the WMO Commission for Agricultural Meteorology) wasn't the only one to be given the boot?

Nev wrote:Thanks for link(s) RWood. Surprised that the national average temp is calculated from only 7 indicator stations. Seems very limited. The national average June temp being just 0.7°C below the norm still sounds a little dubious though.

Just to clarify, I was only questioning Akld temp stats in NIWA's June summary, also showing just 0.7°C below average, which is obviously wrong.

However, I'm a little perplexed by some of the other main centres as well. The Dunedin mean-temp appears to be taken from Dunedin Aero (5.2°C), rather than Musselburgh (6.6°C) and Hamilton appears to be taken from the Hamilton Aws (7.2°C), rather than Ruakura (7.1°C). Haven't checked to see how accurately they relate long-term averages, but wouldn't be surprised if they're out as well.

Given all the other discrepancies (did you query the highest June temp being 24.5°C recorded at Henderson on the 29th btw?), it does make one wonder just how much of a shambles the rest of the preliminary summary is?

Perhaps Jim Salinger (now an honorary research fellow at Akld Uni and president of the WMO Commission for Agricultural Meteorology) wasn't the only one to be given the boot?

It's a space-time tradeoff, but NIWA tell me the matter is being reviewed. However, looking at the series as it stands and the various monthly summaries, I think it is doing a fairly good job.

Yes, the Dunedin numbers are from the airport whereas they were previously from Musselburgh. The report should say so. The promised alteration for Kelburn hasn't happened yet.

Someone else queried the 24.5C error, haven't heard the outcome. When it comes to the data I always rely on the monthly stats. reports - if I see anything fishy there that is of interest I usually tell them.

I just eyeballed a few of the maximum temp. anomalies in the early part of the report and compared them with the 30-year normals, and they looked OK.

Note that there are 2 days of missing sunshine data for Akld last June, which would probably put Akld near equal with Hamilton and Tauranga for the month (assuming Tauranga's figures are correct - not sure where they came from for last month?).

Did you look at Cliflo? I just did a preview and there are 30 lines of data for June, so must all be there.

Ah! They must have just been updated in the last hour or so. NIWA's June summary has 130 hrs (129.7) for Akld, so should be 138.2 hours. Ok, so not quite on par Hamilton and Tauranga.