1909 and all that

[RWood]

(Was getting a bit off-topic, so started a new thread)...

1909 and all that…

Looking in old Gazettes in the library – Feb 1909, Auckland’s month of nil rainfall (site was in Mt Eden), was extremely dry in the northern half of the North Is, and fairly dry in most other parts. The previous year, the summer 1907/1908 was very dry, with Jan-Feb 1908 giving one of NZ’s driest ever spells – nil rainfall at Nelson in February. Scrub/bush fires broke out in many parts of the country, especially in February. March 1908 put an end to that, with big rainfalls and very unsettled conditions.

December 1916 saw nil rain in Wellington, and very low totals in central districts. It followed a wet spring locally, but the year 1916 was NZ’s
warmest to date, not surpassed for another 40 years. There was a strong
La Nina from mid 1916 to Autumn 1918.

Wellington’s wettest month was also a December, in 1939. The two wettest events saw one-day totals of 6.00” and 4.48”, with 15.21” (386 mm) for the month. The S/SE fringe of the NI was the only part of the country with unusual rainfall. In one of the events a front was stationary through the Baring Head area, and it copped 300-400mm I understand, with over 600mm for the month. A strong El Nino prevailed for most of the time from Spring 1939 to Autumn 1942, with mean pressures at Kelburn from June 1939 to May 1940 being the lowest ever for a 12-month period.

[tich]

A strong El Nino prevailed for most of the time from Spring 1939 to Autumn 1942, with mean pressures at Kelburn from June 1939 to May 1940 being the lowest ever for a 12-month period.

July 1939 was the month which saw probably the most extensive snowfalls ever recorded since European settlement of NZ. Could El Nino have been a factor in that?

[Gary Roberts]

A strong El Nino prevailed for most of the time from Spring 1939 to Autumn 1942, with mean pressures at Kelburn from June 1939 to May 1940 being the lowest ever for a 12-month period.

July 1939 was the month which saw probably the most extensive snowfalls ever recorded since European settlement of NZ. Could El Nino have been a factor in that?

Snowfall seems to have been diminishing every year for perhaps a decade down this way. People keep telling me "we're due for a Big One, just you watch out!", yet each year sees less snow fall on average than the previous one.

[RWood]

A strong El Nino prevailed for most of the time from Spring 1939 to Autumn 1942, with mean pressures at Kelburn from June 1939 to May 1940 being the lowest ever for a 12-month period.

July 1939 was the month which saw probably the most extensive snowfalls ever recorded since European settlement of NZ. Could El Nino have been a factor in that?

I think could well have been. It is the case that MSLPs in July 1939 and Aug 1939 were very low (both averaging only about 1001-1002 at Kelburn), and someone at Metservice told me that he understood that the combination of coldness and very low NZ pressures required a very cold Tasman sea. Perhaps the pre-Nino and Nino conditions allowed that situation to develop.

[RWood]

July 1939 was the month which saw probably the most extensive snowfalls ever recorded since European settlement of NZ. Could El Nino have been a factor in that?

Snowfall seems to have been diminishing every year for perhaps a decade down this way. People keep telling me "we're due for a Big One, just you watch out!", yet each year sees less snow fall on average than the previous one.

Haven't had any chance to check, but would it be the case that the last decade in the MacKenzie has been fairly dry overall?

[Gary Roberts]

Haven't had any chance to check, but would it be the case that the last decade in the MacKenzie has been fairly dry overall?

I'm not sure that it's much drier than previously. The last three summers have been a lot wetter than normal. Recent winters have been, as usual, settled and mostly fine, but warmer with little precipitation, including snow. The tops still get it, but even there it's not as deep as I recall...[warning! human memory alert!]...it may be a temporary "glitch", or the shape of things to come.

[nzmaninsydney]

July 1939 was the month which saw probably the most extensive snowfalls ever recorded since European settlement of NZ. Could El Nino have been a factor in that?

Snowfall seems to have been diminishing every year for perhaps a decade down this way. People keep telling me "we're due for a Big One, just you watch out!", yet each year sees less snow fall on average than the previous one.

I can remember the big snowfalls of August/September 1992 in Christchurch (I was 16 years old and living in Sumner at that time), I can remember at that time-people said it was the "Big One".

[Manukau heads obs]

phiilipenes had 3 weeks of non stop rain
but the UK has had a winter drought
see:
http://www.stuff.co.nz/stuff/0,2106,3583445a12,00.html

the roller coaster world weather is continuing

[jrj]

......as it has for centuries.......

[Manukau heads obs]

its just now we know about it instantly via the internet!
LOL

[jrj]

exactly.

[RWood]

Meanwhile - locally (other parts of central NZ in particular may turn up with similar anomalies):

For the 7-month period August 2005 to Feb 2006:

rainfall (approx) 417 mm (only 4 years lower in 140+)

average rainfall 665 mm
record high 1080 mm in 2003/4 (Feb 2004 a huge contributor!)
record low 284 mm in 1914/5 (in a very dry period, 1914-1916)


Sunshine 1608 hrs - record high, previous 1546 in 1910/11 (100 years' data)

average sunshine 1360 hrs
record low 1131 hrs in 1992/3

Mean temps above average, haven't got enough data yet

[RWood]

Haven't had any chance to check, but would it be the case that the last decade in the MacKenzie has been fairly dry overall?

I'm not sure that it's much drier than previously. The last three summers have been a lot wetter than normal. Recent winters have been, as usual, settled and mostly fine, but warmer with little precipitation, including snow. The tops still get it, but even there it's not as deep as I recall...[warning! human memory alert!]...it may be a temporary "glitch", or the shape of things to come.

A rough check for the last 5 years from NIWA commentaries and Tekapo records shows 2001 & 2005 as very dry, 2003 dry, 2002 & 2004 near normal. But of course temperatures and the timing of snow-favouring events make snowfall a very complex thing for anyone to analyse. I can vaguely recall Salinger and others noting from a survey that the snowpack on the Alps was pretty small leading into this summer.

[Gary Roberts]

A rough check for the last 5 years from NIWA commentaries and Tekapo records shows 2001 & 2005 as very dry, 2003 dry, 2002 & 2004 near normal. But of course temperatures and the timing of snow-favouring events make snowfall a very complex thing for anyone to analyse. I can vaguely recall Salinger and others noting from a survey that the snowpack on the Alps was pretty small leading into this summer.

Are they referring to an average year, or summer specifically? As far as I can tell the last three Christmas-New Year periods have been substantially wetter than the average for that period in Omarama and up the Waitaki valley, but I may be wrong.

NIWA have rain gauges at various MacKenzie sites, and very near the Divide in particular, but I believe the Tara Hills AWS was the only one operational around the southern Mackenzie and Waitaki Valley.

[RWood]

A rough check for the last 5 years from NIWA commentaries and Tekapo records shows 2001 & 2005 as very dry, 2003 dry, 2002 & 2004 near normal. But of course temperatures and the timing of snow-favouring events make snowfall a very complex thing for anyone to analyse. I can vaguely recall Salinger and others noting from a survey that the snowpack on the Alps was pretty small leading into this summer.

Are they referring to an average year, or summer specifically? As far as I can tell the last three Christmas-New Year periods have been substantially wetter than the average for that period in Omarama and up the Waitaki valley, but I may be wrong.

NIWA have rain gauges at various MacKenzie sites, and very near the Divide in particular, but I believe the Tara Hills AWS was the only one operational around the southern Mackenzie and Waitaki Valley.

That was for the whole-year period - I should have made that clearer. I could look up Tara Hills AWS (summer and annual) given a bit of time (don't have any others to pick in the southern/eastern parts of the Mackenzie, as you say)

[RWood]

Are they referring to an average year, or summer specifically? As far as I can tell the last three Christmas-New Year periods have been substantially wetter than the average for that period in Omarama and up the Waitaki valley, but I may be wrong.

NIWA have rain gauges at various MacKenzie sites, and very near the Divide in particular, but I believe the Tara Hills AWS was the only one operational around the southern Mackenzie and Waitaki Valley.

I can quote some seasonal numbers for Tekapo and Tara Hills EDR (see below). Of course to know what's going on in a general (let alone a predictive) sense, especially in the higher country with respect to snowfall, one would need among other things a good network of stations, not an easy thing to arrange as you know. In more accessible parts of NZ, eg around Welling.ton and Auckland, there have been enough observing sites to do a geographical-statistical analysis of how the predominant synoptic situations affect various parts of a region. It's not simple stuff - I recall the greater W'gton region and adjacent hill country is thus split into 5 or 6 zones that respond differently to the various situation types.

But back to the seasons (the Tara Hills stuff has estimates for several missing months' data): 2000 was a very wet year over a large part of the southern half of the SI - Tek. and TH were wet in summer and autumn and a little less so for winter and spring.

Since then things have generally been drier. However TH has had 3 of the last 5 summers (to 2005) wetter than usual and has had 124% of normal for the 5 summers overall. The other 3 seasons have been dry more often than wet, averaging only 56%, 73% and 67% of normal overall. Tekapo has been a bit more "even" - S/A/W/S averaging 106/65/80/81 % repectively for the 5 years.

Finally it's interesting that the seasonal variations in 30-year averages vary quite a bit form place to place, though the differences aren't great in the Mackenzie - Tara Hills' wettest "season" on average is Oct-Dec, driest Jul-Sep (ratio 82%), whereas Tekapo has Jun-Aug wettest and Dec-Feb driest (ratio 72%). At Airies (station?) near Burkes Pass things are different again.

[RWood]

GR - did you see this post? (just that I had to muck around quite a bit compiling it...)