Past October weather

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Michael
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Past October weather

Unread post by Michael »

Perhaps it should have a topic of its own.
Where you get yours then?Do you have how many mm?Mine was from the NZ Herald.Why are there descrepencies with the 2 sets of data then?
RWood wrote:Michael - those numbers I quoted were from a well-established Auckland site.
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David
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Re: Past October weather

Unread post by David »

Michael wrote:Why are there discrepancies with the 2 sets of data
This is also something I would like to know. Why is the rainfall here usually higher than elsewhere in Auckland?
I've recorded 973mm for this year but if you search around the other Auckland weather stations you'll be finding totals up to 250mm lower. #-o
If you look at this image attached this is probably the reason for the differences in the two sets of data.


Rainfall distribution is predominantly governed by topography. Elevated areas of the Waitakere and Hunua Ranges, Hotea Catchment and One Tree Hill, all receive high annual rainfall when compared with other parts of the region. Areas of low rainfall occur in proximity to the Kaipara and Manukau Harbours, and over the Hauraki Gulf. This is evident in rainfall records, which show an average annual rainfall in the Waitakere Ranges of 2030mm while Tiritiri Matangi Island receives only 950mm. An annual rainfall distribution map for the region is shown below.
From ARC website

One thing I'd like to know is why out in the Hauraki Gulf there is much lower rainfall and also why there is less around the harbours?
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RWood
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Re: Past October weather

Unread post by RWood »

The comments I made were based on the "Climate Digest" monthly summaries. From memory, the site was Owairaka.
Anyway, the discrepancies weren't very large, and either way my point remains valid - most of those Octobers had average or warmer than average temps., and several weren't "wet" by any sane definition base on typical local data.

You can always expect a fair amount of variability in a region as large as greater Auckland.
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Re: Past October weather

Unread post by RWood »

David, I can't read your map properly. In fact, further out on the "Barriers" the mean rainfall is much higher than most of the city in places. 30-year averages: Waiheke (Awaroa Valley) 1257 Port Fitzroy 1797 Little Barrier 1327.
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David
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Re: Past October weather

Unread post by David »

Yes well the average here is 1300mm+ and the map shows under 1200
I think it might be a little inaccurate/outdated?
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Re: Past October weather

Unread post by NZstorm »

Mean October temp at Auckland Airport 1980-2000 14.4C

2001 16.1C up 1.7C :)
2002 13.3C down 1.1C :(
2003 13.7C down 0.7C :(
2004 14.2C down 0.2C :(
2005 14.8C up 0.4C :)
2006 14.1C down 0.3C :(
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Re: Past October weather

Unread post by David »

2001 must have been very wet October with many winds from N and E quarters. I's say 2002 the following October must have had persistent southwesters, cool nights and days and more southerlies spreading up NZ.

October seems to be a very changeable month, maybe the most changeable month of the year as the weather patterns break out of the wintry mode and start improving in November. Always seems to be an unstable month such as what Auckland's been having recently (maybe not that dramatic though).

Last two Octobers here have been fairly wet, in the first two weeks of October 2005 there had already been 180mm rain. I'd also assume by seeing RWood's rain stats that if the rainfall average was updated to take into account more recent recordings (2000 onwards) that Auckland's average October rainfall would have increased slightly.

October some cold periods which can often be colder than September itself. In 2006 the average daily maximum for September here was 17.7C and the average in October turned out at 17.6C. Also last year October's lowest temperature was lower than that of September by 0.5C.

Either it has just been a run of unsettled Octobers, or, as is extremely common these days, we can blame 'global warming'.
Also I've often found that if Winter does not offer much action usually some is served up in spring, and vice versa - but I don't know whether that is me just losing the plot or just that I have not observed for long enough (which makes it hard to discuss climatic averages on the forum :( )
Last edited by David on Wed 03/10/2007 22:16, edited 1 time in total.
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Re: Past October weather

Unread post by Michael »

Can remember the 31st the rain teamed down I think it was 02
David wrote:2001 must have been very wet October with many winds from N and E quarters. I's say 2002 the following October must have had persistent southwesters, cool nights and days and more southerlies spreading up NZ.
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Re: Past October weather

Unread post by Michael »

Used to be able to go swimming in October it was so warm,now its cold in December to go swimming
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Re: Past October weather

Unread post by David »

Some statistics from the Owairaka station:
October totals:
2001 - 70.5mm
2002 - 78.7mm
2003 - 144.0mm
2004 - 106.5mm
2005 - 209.4mm
2006 - 188.3mm

average for Sep 2001 - 2006 is 95.2mm
average for Oct 2001 - 2006 is 132.9mm
average for Nov2001 - 2006 is 76.7mm

This therefore proving that in the last six years October has been much wetter on average and by far the wettest month of spring on average over the six year period. If the current weather patterns keep up then we'll be on track for another wet October.
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RWood
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Re: Past October weather

Unread post by RWood »

You can't conclude anything much from 6 years of data: Here's a set of Sep-Oct pairings for 30-year means from some of the Auckland stations (in Northalnd the difference is more pronounced, with Cape Reinga 50% wetter in Sept).

122 92
127 98
119 94
119 98
118 92
114 87
137 110
106 90
95 85
197 182
181 158
203 186
116 91
108 85
108 86
108 86
113 95
112 88
97 84
114 96
spwill
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Re: Past October weather

Unread post by spwill »

I seem to remember much of the rain here last October fell in the first 4 days of the month with TStorms then a boring month.
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Re: Past October weather

Unread post by David »

RWood wrote:You can't conclude anything much from 6 years of data
Yes but remember Michael saying the last six Octobers have been wet? Although he is not completely correct there, the average rainfall for the last six Octobers has been fairly high compared to the long term mean.
spwill wrote:I seem to remember much of the rain here last October fell in the first 4 days of the month with TStorms then a boring month.
True for some, but most of those flooding downpours were in the central districts, with only 48mm here in the east in the first 4 days. Another 102mm fell for the month after that. But all this really proves is the strong local variability in Auckland.
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David
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Re: Past October weather

Unread post by David »

Don't know where to put this, so I'll put it here. Made a conclusion and analysis about Auckland rainfall.
Auckland rainfall stats and patterns:
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Re: Past October weather

Unread post by RWood »

The decrease is consistent with the fact that a La Nina-favouring PDO that covered 1948-1976 was followed by an El Nino-favouring phase that hasn't really ended yet.
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Re: Past October weather

Unread post by NZstorm »

Mean October temperature for Christchurch 11.6C (1980 to 2000)

2001 12.3 up 0.7C :)
2002 10.1C down 1.5C :(
2003 10.5C down 1.1C :(
2004 10.8C down 0.8C :(
2005 10.9C down 0.7C :(
2006 11.4C down 0.2C :(
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Re: Past October weather

Unread post by janewaystv »

Well done David - really excellent graphs and data - keep up the good work matey :D

I remember 1993 quite well - the low rainfalls (apart from June and August) contributed to the water crisis of 1994.
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Re: Past October weather

Unread post by RWood »

NZstorm wrote:Mean October temperature for Christchurch 11.6C (1980 to 2000)

2001 12.3 up 0.7C :)
2002 10.1C down 1.5C :(
2003 10.5C down 1.1C :(
2004 10.8C down 0.8C :(
2005 10.9C down 0.7C :(
2006 11.4C down 0.2C :(
However - to compensate somewhat for the cold - 2002 Oct was easily the sunniest on record (272 hrs), and 2003 at 235 did well in that respect also. :)
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Re: Past October weather

Unread post by RWood »

PS - October 2001 was also wet and cloudy in many areas, including Christchurch! Just baldly listing those temp. anomalies gives a wrong impression.
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Re: Past October weather

Unread post by tich »

PS - October 2001 was also wet and cloudy in many areas, including Christchurch!
First half was warm and sunny; 2nd half cool and wet, rainfall ending up above normal.
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Re: Past October weather

Unread post by RWood »

By the start of Oct 2001 the central regions were rather desperate for rain after an exceptionally dry and sunny 12 months (overall). Many native plants were under severe stress, made worse by the dry September conditions. The weather changed here almost instantly at the start of October - a few cloudy days, then about 90mm of rain from 7th to 9th. The month was cloudy and damp overall, which was just as well really (though I was fortunate enough to be out of the country on holiday at the time). Wet unsettled weather through to January sorted out the dryness in the affected areas.
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Re: Past October weather

Unread post by David »

As with last time I'll post here...
Been downloading statistics from the National Climate Database and then processing & analysing them in my spare time recently. I've done one on temperatures for Auckland as well (not an attempt to impress, but may as well share the data and also see if anyone has opinions/thoughts), I know it isn't as well organised as it could be but hopefully it is easy enough to follow (and it takes about 2 hours to create!). My analysis (graphing) pretty much supports global warming - but whether or not that is caused by humans is for the individual to decide.

I should also some time do the same for few other major centres around NZ and compare the findings, but that will take time and also I only have the weekend left before the end of holidays :(
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Re: Past October weather

Unread post by janewaystv »

Just had a quick glance at AKL's temps - (In terms of actual temps & trendlines).

Summer - gradual declines

Autumn - alternating from year to year but May warming up quite considerably

Winter - stable apart from June which was getting warmer but has declined sharply over the last 2 years.

Spring - stable with September being warmer and November being the most stable.

So one could draw a conclusion that cloudier weather brings warmer temps with more wet NE - E patterns and sunnier weather brings cooler temps with more drier SW - W patterns especially during summer - autumn.

Auckland temps. seems to have a small annual range - compared to many other countries. Sydney's annual range is smaller in the summer and higher in the winter.
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Re: Past October weather

Unread post by NZstorm »

Thanks for the info guys.

I did a 4 year running mean of the airport temps and its shows warming and cooling trends nicely. It does look like Auckland ( and the rest of NZ) is entering a warming phase so some very mild seasons a head for the next few years. :)
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