General December Weather

[Razor]

Hot hot hot here today, nearly hit 30 with high humidity to boot. Very unusual conditions

[NZstorm]

Looks like the top of Northland should catch some of the thunderstorm activity tomorrow.

[jamie]

i like the looks of Sunday afternoon for storms in the Waikato. GFS is currently plotting LI of -4 over the Waikato.

New thread time for this sub tropical low i think

[NZ Thunderstorm Soc]

Nice sunset this evening
Orange Sc line west to east with a nice moon observing over

[NZ Thunderstorm Soc]

Can't wait until tomorrow's or this evening's overnight southerly change.
It should be very interesting with low cloud, mid-teen temperatures after a, probably, bit of rain.
The chance of any thunderstorm activity should be from a range of 0 to 40 NIL
I love this La Nina weather

[Orion]

Southerly change just arrived here in the last few minutes.

[snowstormwatcher]

Southerly change has just arrived here too.
High of 24 degrees.

[Richard]

Thick heavy drizzle here this morning,9 mm so far and 13deg

[Michael]

It be interesting reading the summaries for 2011 once things get back to normal,Ithought in akld its been a calm windwise year apart from november,even winter wasnt lots of wind days,the best part was aug 15th

[David]

Some pretty large December rain totals looking at the metservice site - Tauranga 272mm, Rotorua 342mm, New Plymouth 339mm, Nelson 445mm, looks like Kerikeri got over 400mm too but can't get the historical graphs to load for there.

Auckland Airport had 191mm. I recorded 137mm so not that wet here. Apparently Whangerei only had 101mm.

[Manukau heads obs]

240mm here, I think that was a record for here

[snowstormwatcher]

pretty much an average December here weatherwise.

Avg max 20.7
Avg min 9.6
rainfall 66mm

[Nev]

Some pretty large December rain totals looking at the metservice site - Tauranga 272mm, Rotorua 342mm, New Plymouth 339mm, Nelson 445mm, looks like Kerikeri got over 400mm too but can't get the historical graphs to load for there.

Auckland Airport had 191mm. I recorded 137mm so not that wet here. Apparently Whangerei only had 101mm.

Note that MetService's Whangarei Aero site has no available rainfall data for the 30th and 31st of Dec (the 29th looks a little short as well). NRC's city gauge recorded over 60mm during those last few days and over 185mm for the month.

Also worth noting that NIWA's Te Puke EWS recorded about 168mm during the last 48 hrs of Dec, bringing its month's total to 413mm.


P.S. Re Akld sunshine, NIWA's Albany EWS has 187 hrs for Dec as opposed to Mangere's 132 hrs.

[spwill]

P.S. Re Akld sunshine, NIWA's Albany EWS has 187 hrs for Dec as opposed to Mangere's 132 hrs.

I think seabreeze convergence has caused quite a bit of variation in sunshine hrs across Auckland in December.

[NZ Thunderstorm Soc]

We only got 64.8mm here in West Melton for December but the year total was 727.7mm which is about average for here. Just reading the above totals for some areas of NZ makes it sort of a bit of a dry spot here.

[RWood]

P.S. Re Akld sunshine, NIWA's Albany EWS has 187 hrs for Dec as opposed to Mangere's 132 hrs.

As with Paraparaumu EWS, Albany's numbers are way out of kilter with other regional values both north and south of it, and I regard neither one as reliable at this point.

You only have to put the daily readings side by side with mangere to get some really silly contrasts. These are not the only 2 EWS sites with values that are in no way concordant with manual sites and the better-behaved EWSs - the worst current offender is Telford near Balclutha, which is averaging about 400 hours more year than Finegand! Just bollocks!

[Nev]

Had a quick look at the daily sunshine data for Mangere and Albany and can't say as I'd agree with you RWood. Both currently appear to be using the same type of sunshine recorders (Li-Cor Silicon Cell - Global), and the contrasts, although rarely that great, appear to be very consistent with what one might expect of the topographical/microclimatic variation between the two sites. I think spwill is on to it - convergence is typically the culprit here.

[RWood]

Had a quick look at the daily sunshine data for Mangere and Albany and can't say as I'd agree with you RWood. Both currently appear to be using the same type of sunshine recorders (Li-Cor Silicon Cell - Global), and the contrasts, although rarely that great, appear to be very consistent with what one might expect of the topographical/microclimatic variation between the two sites. I think spwill is on to it - convergence is typically the culprit here.

You'd have to come up with a reason why Albany's sunshine levels were up with the BOP values and much higher than Kaitaia (142), Dargaville (124) and Hamilton (136) along with Mangere. Are you suggesting that convergence can also explain away the differences with Kaitaia, which has always been competitive with Auckland sites used thus far? Remember that these recorders can be tweaked to various levels of sensitivity. Philip Eden, an expert in the UK, has written extensively on the problems inherent in both trying to make comparisons with manual (Campbell-Stokes) data, and in managing the EWS recorders themselves. I would also remind you that the Whakatane equipment had to be down-adjusted by NIWA. I believe there is something significantly wrong with Albany, and even more so with the likes of Paraparaumu, Ohakune, Telford, Ashburton, Waipara, Taumarunui and Te Kuiti, to name just a few.

I am not at all convinced by these readings. But if you northerners want to convince yourselves that you've found a locality whose readings are clearly superior, I'll put up the stupid Paraparaumu EWS values as a counter! (they're considerably higher than the manual ones there, but what the hell....)

[spwill]

You'd have to come up with a reason why Albany's sunshine levels were up with the BOP values and much higher than Kaitaia (142), Dargaville (124) and Hamilton (136) along with Mangere. Are you suggesting that convergence can also explain away the differences with Kaitaia, .)

A feature of the months weather was slow moving fronts and E/NE flow, NewPlymouth with good sheltering had 233hrs sunshine. Albany will catch the cloud on a E/NE flow but you need to get north of Owera or even Warkworth to start getting the full cloudiness affects. BOP is exposed to the E/NE.

I don't know if the Albany readings are correct or wrong , best make some Winter/Spring comparisons between Albany and Mangere to get a feel if it is reading too high.

[RWood]

You'd have to come up with a reason why Albany's sunshine levels were up with the BOP values and much higher than Kaitaia (142), Dargaville (124) and Hamilton (136) along with Mangere. Are you suggesting that convergence can also explain away the differences with Kaitaia, .)

A feature of the months weather was slow moving fronts and E/NE flow, NewPlymouth with good sheltering had 233hrs sunshine. Albany will catch the cloud on a E/NE flow but you need to get north of Owera or even Warkworth to start getting the full cloudiness affects. BOP is exposed to the E/NE.

I don't know if the Albany readings are correct or wrong , best make some Winter/Spring comparisons between Albany and Mangere to get a feel if it is reading too high.

Points taken - however my general criterion is sunshine totals over longer periods, say annually. The thing that is generally becoming apparent with many EWSs like (probably) Albany and (certainly) Paraparaumu is anomalously high totals when compared to a range of sites in similar regions, especially against manual ones. The ones I listed already, plus Greymouth, show this very markedly over a period of several years now. If you look at the sunshine anomaly charts in Climate Explorer, time after time you can see positive distortions around these sites because they are comparing values with earlier manual ones. In the cases of EWSs like Blenheim and Kaitaia where the values look reasonable, I strongly suspect the calibration has been set to get good agreement with former manual values - UK Met had that as a specifically stated objective at one point (don't know if it still is). (see next post)

[RWood]

{had to continue here because the editor wasn't showing me the text} ...

I concede that it is still "early" days in the Albany case - the 2010 value (If May had been complete) would have been suspiciously high at around the 2300 mark (over 210 ahead of Mangere), but some lower values in mid-2011 mean its overall lead over Mangere was not all that large this time. However I'll be surprised if anomalies don't soon show up again in months that are not necessarily dominated by the characteristics you mentioned above.

[Nev]

I see Albany's solar radiation sensor was replaced last Sep, so that may explain the recent anomalies. And yes, prior to that most 2011 months were lower than Mangere's, but in 2010 (since records began), most were higher.

Not sure if I've read Philip Eden's particular comments, but the inherent problems in trying to replicate the classic Campbell-Stokes method of recording electronically must be a nightmare. My point was that both Mangere and Albany both appear to use similar modern sunshine recorders.

I do believe however that different areas around Akld don't always receive the same amount sunshine and, generally speaking, I suspect that the central North Shore may well receive a little more than their regional southern coastal counterparts. Bit hard to prove if NIWA's using unreliable sensors though. Now if I could only convince NIWA to set up a sunshine recorder on Waiheke, lol.

[RWood]

I see Albany's solar radiation sensor was replaced last Sep, so that may explain the recent anomalies. And yes, prior to that most 2011 months were lower than Mangere's, but in 2010 (since records began), most were higher.
Not sure if I've read Philip Eden's particular comments, but the inherent problems in trying to replicate the classic Campbell-Stokes method of recording electronically must be a nightmare. My point was that both Mangere and Albany both appear to use similar modern sunshine recorders.
I do believe however that different areas around Akld don't always receive the same amount sunshine and, generally speaking, I suspect that the central North Shore may well receive a little more than their regional southern coastal counterparts. Bit hard to prove if NIWA's using unreliable sensors though. Now if I could only convince NIWA to set up a sunshine recorder on Waiheke, lol.

Yes, a little more for central North Shore may well be reasonable - but one possibly paradoxical thing is that for a number of years there was also a sun recorder at Auckland Aero (1969+), and it was consistently somewhat higher in totals than Mangere was, and similar to the typical values at both the former Mechanics Bay site and concurrent Auckland City site (this latter deteriorated markedly after about 1985, presumably because of changes in nearby buildings or the like). I suppose it is possible that the Mangere exposure was (and possibly still is?) inferior to that at the airport. If that is the case then the north (or central) - south difference across Auckland may be more apparent than real as far as annual timescales go, as a revived Aero site might be getting totals nearer to Albany's. If on the other hand the Mangere exposure was and still is OK, then the difference from the old Aero site needs explanation.... so some unanswered questions. (TBC)

[RWood]

I do hope you can get a sensor set up on Waiheke!

It is certainly true that the "matching" exercise has been a controversial nightmare for the UK met. folk.

Meanwhile to illustrated some extreme EWS cases: Ohakune 1961-74 averaged barely 1800 - EWS suggests after 3 years at least 2075! Balclutha Finegand is not "flash" now but even in its better days was barely near the 1700 mark - Telford near Balclutha after 5-6 years is averaging 2050! South Otago near the coast - please!!
Ashburton had a long record with values no higher than Timaru and considerably less then Ch'ch - around the 1900 mark, now looking more like 2200-2250. And so it goes - Greymouth had decades of values inferior to Hokitika's with their manual sites - now it's the Coast's "sun town" according to its EWS. And so on ...I won't bother re-litigating Whakatane ...

I hope some sense can be made of all this one day!

[Nev]

Here's NIWA's, 'December 2011 National Climate Summary'.

Lots of rainfall records broken, both highest and lowest.