A Change in Weather Pattern

[RWood]

Interesting. OK - what about the "easterly" factor? Might not be a biggie, but it seems to me that it would be easier for cloud to invade upvalley near Omarama than around Tekapo - at least that's what the data for past months with a high frequency of easterly flows indicates.

For a common inversion layer around 600-1000m, presumably Mt John at 1020+m can frequently be in the clear?

I realise this is getting a little off-point...

[Andy]

Nice info Keep it coming.

Inversion layers are common in Central Otago, especially in the Alexandra and Cromwell basins.
These also vary in altitude one around 300-600m and the other at approximately 700-1,200m. The first one being more common in winter the later in Autumn.

[Gary Roberts]

...what about the "easterly" factor...it seems to me that it would be easier for cloud to invade upvalley near Omarama than around Tekapo...

I think I've mentioned a few times in the past that when the wind turns easterly we know the sh*thouse weather is coming. The trash from the coast is pushed up the valley and spills out into the Waitaki/southern Mackenzie. If that pattern lasts long enough or is severe it will spread throughout the rest of the basin.

I spent quite a lot of time surveying the south Canterbury, North and Central Otago region (including Alex and the unpronouncable valley around it) when looking for an observatory site. Lake Tekapo was a frontrunner but we couldn't get the elevation we wanted. The Benmore Range had the advantage of that, as well as being within the region NIWA had surveyed and discovered to have the lowest airborne atmospheric aerosol concentrations then measured. It's also a low rainfall zone (at that altitude) and has more clear skies than Lake Tekapo and most other locations (again the advantage of elevation).

I saw that even though the crap often obscured the lower Mackenzie it was generally at a low altitude. Crud often didn't get north of Mt St Cuthberts, east of the Kirklistons, or west of the Barrier range. So you ended up with an island well above the low clag and spared from the higher stuff which stopped short in most directions.

Lake Tekapo does experience more clear skies than, say, Omarama township, but it also cops howling westerlies and gets a regular sandblasting.

[Andy]

Lake Tekapo does experience more clear skies than, say, Omarama township, but it also cops howling westerlies and gets a regular sandblasting

This is something the new comes too Tekapo are yet to experience

[RWood]

It would be interesting to eventually have a "full" set of climate stats. for any site(s) around the Benmore range, by the sound of things.

With Tekapo it's simply the views - if development doesn't stuff them for many - that enchant me. But then I have fond recollections of looking out from hills just south of Alex. on any decent day - never tired of that.

I could ask Andy some questions re Cromwell/Alex. differences but had better start a new thread for that I think!

[Andy]

could ask Andy some questions re Cromwell/Alex. differences but had better start a new thread for that I think!

Roger that over to General then

[RWood]

Nope, at least not in the Mackenzie. It was significantly warmer than last year and around the same as winter 2005. (Or was it 2004? I forget...)

Possibly a few more cold days but only because we had some snow on the ground (albeit bugger-all), unlike 2004 and 2005 where there was almost no snow at all.

...warmer than normal for northern NZ. Niwa summary for july will be interesting.

I don't know about up north.[/quote]

For the record, now I've mustered the energy to check - the last significantly colder than normal winter for the Mackenzie was 1997 (this applies to quite a lot of places). Around Omarama 2003 winter was the warmest on record, 2005 3rd warmest. 2001, 2004 and 2006 were near-normal. 2002 and 1998-2000 were all warmer than average.

[Gary Roberts]

For the record, now I've mustered the energy to check - the last significantly colder than normal winter for the Mackenzie was 1997 (this applies to quite a lot of places). Around Omarama 2003 winter was the warmest on record, 2005 3rd warmest. 2001, 2004 and 2006 were near-normal. 2002 and 1998-2000 were all warmer than average.

I'd accept that. We weren't here for 2003 but I suspected it was a warm one. 2004 and 2005 were certainly also very mild. 2006 was probably skewed by the snowfall. That snow in itself was only exceptional for the area it covered and the stickyness of it. The depth was not great and it didn't last particularly long.

As for 1997, locals have told me how the snow lay for something like 6-9 weeks (depending on who is telling the story). I'd been down here only a week before that "big freeze", when media (and Tara Hills?) reported temperatures down to -18 °C in Omarama. (Although again and inevitably locals were saying things like -23 °C... )

[RWood]

There was a story about the recent cold in the Maniototo that appeared a couple of days ago on Stuff, and presumably in the ODT. All the temperature claims looked inflated, as usual. Quite entertaining though.

[Gary Roberts]

There was a story about the recent cold in the Maniototo that appeared a couple of days ago on Stuff, and presumably in the ODT. All the temperature claims looked inflated, as usual. Quite entertaining though.

I think I read that. At the time I wondered where they got their readings from. The Maniatoto area does get a mite chilly at times: according to the Met Service, the lowest temp ever recorded in NZ was -21.6 °C at Ophir, on July 3rd, 1995.

[RWood]

This lot were claiming a heap of -19s. It wasn't so much the values as the durations that I found unconvincing...July's summary will comment if it was as tough as they claimed.

[Manukau heads obs]

so far for July, I am now at +0.1 oc above average (for me)
the last few days are bringing the average up...

[spwill]

Pattern is mobile now so Spring like weather looks set to continue.
Perhaps a much warmer than normal Spring on the way for eastern area's due to a lot of NorthWesterlies but the reverse by Summer with the Westerly pattern turning Easterly.

[03Stormchaser]

Pattern is mobile now so Spring like weather looks set to continue.
Perhaps a much warmer than normal Spring on the way for eastern area's due to a lot of NorthWesterlies but the reverse by Summer with the Westerly pattern turning Easterly.

If thats the case wouldnt we be looking at a very active season for the west coast, for spring at least!!

[Gary Roberts]

How are the seasons defined? By start/end dates or by conditions?

[spwill]

thats the case wouldnt we be looking at a very active season for the west coast, for spring at least!!

Yes , but the West Coast spring is always wet and thundery anyway or perhaps RWood can find a dry one ?.

[RWood]

[quote="Gary Roberts

For the record, now I've mustered the energy to check - the last significantly colder than normal winter for the Mackenzie was 1997 (this applies to quite a lot of places). Around Omarama 2003 winter was the warmest on record, 2005 3rd warmest. 2001, 2004 and 2006 were near-normal. 2002 and 1998-2000 were all warmer than average.

I'd accept that. We weren't here for 2003 but I suspected it was a warm one. 2004 and 2005 were certainly also very mild. 2006 was probably skewed by the snowfall. That snow in itself was only exceptional for the area it covered and the stickyness of it. The depth was not great and it didn't last particularly long.

As for 1997, locals have told me how the snow lay for something like 6-9 weeks (depending on who is telling the story). I'd been down here only a week before that "big freeze", when media (and Tara Hills?) reported temperatures down to -18 °C in Omarama. (Although again and inevitably locals were saying things like -23 °C... )[/quote]

Have now been able to check June details: much of SI was between 0.5C and 1.0C colder than average, the national value was 0.6C below. Tara Hills site was 0.7C below. I got my oldest year wrong - 1997 in the south had a warm June and reasonable August temps, just a shortish cold patch in July. But 1996 was cold in both June and July, and 1995 was the topper - after an ordinary June, July (especially) and August were cold. July 1995 saw Ophir get the new record of -21.6C, and Omarama dropped to -19.5C around the same time.

[RWood]

thats the case wouldnt we be looking at a very active season for the west coast, for spring at least!!

Yes , but the West Coast spring is always wet and thundery anyway or perhaps RWood can find a dry one ?.

There have been some notable exceptions. 1974 and 1985 "spring" to mind first up.

[03Stormchaser]

Yes , but the West Coast spring is always wet and thundery anyway or perhaps RWood can find a dry one ?.

Not always the case. The last couple of years, spring/summer, there hasnt been the thunderstorms that the coast is knowen for.

[Andy]

But 1996 was cold in both June and July, and 1995 was the topper - after an ordinary June, July (especially) and August were cold. July 1995 saw Ophir get the new record of -21.6C, and Omarama dropped to -19.5C around the same time.

That was the last very cold year in Central; if i remember right the Shotover River in Queenstown froze over for the first time in 100 years. The cold temps followed after a reasonable snowfall the lay around for a few or more weeks.

Rwood When you have time, could you dig out the data for Alexandra. Lowest air min temp, max air temp ect.
Thanks

[RWood]

Andy, I can't generally confirm all-time records for Alex (only have printed data from 1955 to present, except for complete records of monthly rainfall and sunshine).

However the highest max. record is 38.7 on 4/2/2005.
Lowest min up to end-1998 (probably still valid) was -11.7C (got this from MetService site, no date given).

if you register on the Cliflo service (free) at NIWA you should be able to construct a query to get the max & min temps. for Alex. for each month of the year. I've managed to do this sort of thing and it's not too hard. The key is to fill out a request profile which identifies the stations in your query by the Station Agent Number(s).

[Andy]

Ok thanks

[Michael]

Hope this one comes out...bound to change a week out