Settled weather for the week starting 4th August

[Michael]

David youre much furthur east than me,like today theres still a huge bank of cloud to the SW,We cannot shake off these anticyclonic SW till the Rain from the next system is on our back doorstep.Everywhere else in the country gets a good fine spell(I mean cloudless or next to nothing)Anticyclones here unless we get good SE or NNW flows are rubbish here.There was a friday about 2 weeks ago that was fine and even think that day it was more than a 24 hrs precipitation break.At least with a low you can guage the weather but some of these anticyclones....

[spwill]

Kaitaia (1951-2006) 54 53 51.5 51 49 45 49 50 50 48 49 50 50
Auck City (1933-1985) 55 54 50 51 47 42.5 47.5 47.5 46.5 48 49 52 49.5
Mangere (1964-2006) 54 54.5 51 50 46.5 41 45 46 44.5 46 47.5 48 48
N Plymouth Aero (1973-2006) 57 60 56 55.5 48.5 44 48 50 47.5 49 49.5 50 51.5RWood

Thanks RWood.
Do you have some numbers for eastern locations and Wellington.

[Nev]

October's usually the one for wind; "Gales of the Antarctic Dawn" as Bob McDavitt puts it.

Yes, for Auckland, October and November are months that under perform( low sunshine and windy ) due to the westerlies that crank up over NZ at this time. ...

Yes, westerlies strengthen across NZ due to the increasing polar/equator temp-differential as the sub-tropics begin to warm relatively faster. Perhaps 'equinoctial gales' would have been a more appropriate term (just really like Bob's phrase ).

However, as RWood's figures suggest, actual sunshine hours at Mangere for October and November would normally be above the yearly average.

[RWood]

Kaitaia (1951-2006) 54 53 51.5 51 49 45 49 50 50 48 49 50 50
Auck City (1933-1985) 55 54 50 51 47 42.5 47.5 47.5 46.5 48 49 52 49.5
Mangere (1964-2006) 54 54.5 51 50 46.5 41 45 46 44.5 46 47.5 48 48
N Plymouth Aero (1973-2006) 57 60 56 55.5 48.5 44 48 50 47.5 49 49.5 50 51.5RWood

Thanks RWood.
Do you have some numbers for eastern locations and Wellington.

OK - here's some more, but note the caveats:

(1) Up to date profile info. is not available
(2) Differing timespans and stability - if you just take the last 30 years there are some changes as Wellington and particularly Christchurch have increased their averages significantly over the period (see below). Also site changes at Nelson and Blenheim.

Napier (1930-2006) 57 55 54.5 52.5 52 51 49.5 51 53.5 55 54 54 53.5
Blenheim (1930-2006) 59.5 61 60 59 59 58 58 57 57.5 57 55 58.5
Nelson (1930-2006) 61 62 60.5 61 59.5 57 59 58 58 56 57 55.5 58.5
Wellington (1928-2007) 55.5 55 52.5 50 44.5 40.5 41.5 45.5 48.5 49 51 51 49.5
Christchurch (1949-2006) 49.5 50.5 47.5 50 46.5 47 46 49 48.5 50.5 50.5 46.5 48.5

Last 30 years only: Kaitaia 50
Mangere 48
N Plymouth 51.5
Napier 53
Blenheim 58
Nelson 58.5
W'gton 50.5
Ch'ch 50.5

[spwill]

The cloudier spring weather for the west of NZ shows up well in those numbers.

[David]

David youre much furthur east than me

Oh come on, its probably only a matter of a dozen (or two) kilometres - and this statement doesn't apply when I bring up clear weather, because if I couldn't see any clouds there is a mighty good chance you couldn't either!

Blenheim (1930-2006) 59.5 61 60 59 59 58 58 57 57.5 57 55 58.5
Nelson (1930-2006) 61 62 60.5 61 59.5 57 59 58 58 56 57 55.5 58.5

It is interesting that December is the month during which Nelson and Blenheim record the lowest percentage of sun out of the total sun possible. Any reason for this?

The cloudier spring weather for the west of NZ shows up well in those numbers.

Do blocking or sluggish anticyclones have a lower tendency to occur in spring than the other seasons? This perhaps a reason for cloudier springs?

[RWood]

Blenheim and Nelson are not alone in that regard. I'll shortly post an older list (only based on data up to about 1998) of averaged % for both islands. It will have altered a little by now, but December still wouldn't rate very well. The slow spring start in the western locations is simply (at least primarily) due to the westerlies, as is the relative spring superiority in eastern districts.

[spwill]

Do blocking or sluggish anticyclones have a lower tendency to occur in spring than the other seasons? This perhaps a reason for cloudier springs?

Yes, the pattern is more mobile from the west in spring also High preasure often tracks through the central Tasman at this time keeping the west of the country in post frontal cloudy southwesterlies rather than clearing Southerlies.

[NZstorm]

Yes, the late spring/early summer north Tasman high is the reason we get so much cloud in Auckland at that time. It casts a large tempertaure inversion over us and directs a moist SW flow onto the west of the North Island. This means stratocumulus is a fairly typical cloud October to December and it keeps our mean daily maximum quite low too given the time of year.

[RWood]

I don't have a satisfactory version of the older lists anymore, but anyway for the South Island December ranked last or last equal. It would still rate fairly low if one could update the numbers.

For 3 patterns different from any in the North Island (though for Dunedin and Invercargill the averages have increased significantly in recent years) these are interesting:

Timaru - winter maximum, summer minimum

44 44.5 42.5 46 46 49.5 48 48 46 45.5 45 41 45

Dunedin - small range, but slightly higher in early autumn and early spring

40 42 40 41 38.5 39 40 42 42 41 39.5 37.5 40

Invercargill - late autumn minimum, sharp drop from February

40.5 42.5 38 35 31.5 30 35.5 40.5 41.5 41 41 40.5 38.5

[David]

Not much rain from the front overnight at all! 3mm here. Was surprising that at school today there was a very heavy downpour before 10am for 5mins or so - the eastern beach station recorded 4mm, and I get home to find that there was 0.2mm

[NZstorm]

Yes, I noticed those big t/cu and showers this morning. A bit of early mositure triggered them. A drier brighter day followed though with 17.6C here in Grey Lynn.

[Manukau heads obs]

rather wettting frequent drizzle/light rain showers here at the moment now