Can someone please help me out!

I'm looking for 30+ years of historical snowfall data, preferably daily observations, but weekly would be sufficient.

Cheers

Sorry, the majority of us use second hand anecdotal evidence to support our assertions.

I've emailed snowy hydro, hopefully they don't do the same.

Interesting to see if they do a depth reading at Spencers tomorrow. There was a good cover above the road where they do the measurements.

Hydro only get their data intermittently, if you were after regular data you would have to interpolate it between readings. It is also only snow pack depth so not a true indication of snowfall.

I was keen to do a extreme event analysis on the data they do have to get average reccurence intervals for max depth but still trying to source it.

Yeh, that's fine, it doesn't have to be super accurate. I just need something more reliable than peak season depth. I was thinking of snow "depth days", i.e. depth*days so I get some kind of measure of the quality of the season as a whole.

Have a look here

Gerg is the man when it comes to Spencer's Creek statistics

Having said that, I'd like Gerg to replot the last few decades of this graph with greater temporal resolution, as it seems to me that seasons are definitely getting shorter and shorter.

The only recent seasons that have positive anomlies later in the season are the Pinatubo seasons of '91 and '92.

My pre-season prediction for the 2012 Spencers Creek peak snow depth is 105 - 210 cm, with best estimate 160 cm.

Basis

My method uses a statistical model based on multiple linear regression with the winter (JJA) averages of AAO, SOI and IOD, and with calendar year. I exclude periodicity (because there is none) and PDO (because the correlation is poor - below). The basic correlations look like this (2011 highlighted):




That leads to the regression model:

Peak depth (cm) = 1330 - 28 x AAO + 1.65 x SOI - 10 x IOD - 0.57 x Calendar Year

...which performs as follows:



The correlation coeficient is 0.3 and the standard error is 53 cm, so about 70% of historical years fall within +/-53 cm of the model.

2012 Parameters

Antarctic Oscillation (AAO; also called "Southern Annular Mode")

AAO is a measure of how tightly the circumpolar winds ("polar vortex" in one usage) blow around the pole. A loose pattern (negative AAO) leads to more polar storms reaching southern Australia, and more snow.

This is the most important parameter and the hardest to predict. The data look like this:



My prediction for the 2012 winter is +0.5 (slightly negative for snow).

Southern Oscillation Index (SOI, an indicator of ENSO)

SOI is the difference between Tahiti and Darwin surface atmospheric pressures expressed as monthly standard deviations x10. It is an indicator of the El Niño Southern Oscillation, an east-west quasicycle in Pacific Ocean surface temperature and wind patterns which correlates with precipitation across much of Australia, including with alpine snow. A positive SOI is associated with more (and some say wetter) Australian snow.

The various numerical ENSO forecasts look like this (for the Niño3.4 sea surface temperature index, which is negatively correlated with the SOI):



My prediction is that Niño3.4 will be slightly positive and therefore SOI slightly negative at -5, which is slightly negative for our snow.

Indian Ocean Dipole (IOD)

The Indian Ocean Dipole is an ENSO-like variation in the smaller Indian Ocean, which correlates with precipitation across southern Australia, including with alpine snow.

The BOM numerical prediction is neutral:



My prediction for IOD this winter is 0, which is neutral for our snow.

Prediction

Based on those parameter predictions, I predict that there is about a 70% chance that the 2012 peak snow depth at Spencers Creek will be between 105 cm and 210 cm, with the most likely peak depth 160 cm. The probability of a peak depth above 2 m is a little over 20%.

That's what I'm going to try and do. I'll have a mess around and come up with the best measure of a "good" season.

Snowy hydro have passed the buck twice already. I'm now waiting for a reply from Andrew from Cooma. Surely it should be publicly accessible data anyway, they have published their electricity market data at 30min intervals; why not the snow data?

This is a perfect example of someone trying to manipulate the data to show what they want it to show. You've established your hypothethis, now you just need to hand pick the data set to show you are correct.

You can't just claim data snooping; you have to show how

The data are publically available here; just not in a very friendly format. Choose year, mouse over graph to pop up data, guess date (most are Thursdays), write down number, repeat (about 1000 times).

The best measure of season quality is season integral depth ("metre.weeks"), because it incorporates season length as well as depth. It's just all the weekly depths for the year added up. The season integral depth record looks like this:

Thanks Gerg - the Integral Depth chart does a good job of demonstrating the trend.

I'm too lazy for that I think. If snowyhydro send me the raw data I'll let you know via PM.



I was thinking something similar. I might restrict the data somehow, maybe only look at the integral up to 200 cm. I don't really think there's much difference between a 2m and 3m base (skiing wise), but the data would be significantly skewed from these larger values.

There is a more to what makes a "good season".

How much snow do we need to be a good season,
When I worked in 81 there was huge falls and lots of bad weather, sometimes days of rain and snow mix.
Not the best skiing conditions a lot of the time due to it.
First month was bashing rhime off lifts all the time to keep them going and lift stoppage risk increases with too much bad weather and snow.

More does not always equal better for our purposes, after all lifts and runs are open how much more do we need.
Nor does it always assure the season last longer.

We have plenty of years that have poor conditions at start or end and one one huge peak.
Seasons that have lasted longer with no large peaks just regular top ups, and lack of snow killing events.
The ones that lasted longer and more average mix of weather gave more good ski days.

There is low point where it is a less than good season for our purposes.
Look at the graph at years that levels exceeded 20CM in every 10 year period.
For the purpose say under 20 it is poor.
40+ is too much
30 is Epic which is nice but doesnt open more in bounds terrain or lifts.

The last 10 years we had 7 seasons at 20 or more
Same in first 10 years in the graph.

My father was going when those big peaks came in the 50s and they could hardly access the place.
Snowing in mansfield they had to wait for the plough to clear the roads all the way to Buller.

The best season we can hope for IMO is one with more average falls over the season and less snow killing events since it will equate to more ski days on good enough cover with more small snow events to freshen up to top layer.
No prolonged periods of bad weather that we have gotten with big years.

Integral above some threshold may be better, but I'd suggest rather less than 2m. Deep seasons are just better skiing, because more snow falls, so the surface is in better condition more often (even after full coverage is achieved).

Probably the threshold should change through the season. Shallow Spencers depths in June are generally associated with much better skiing than the same depths in September.

IMO, 2004 was one of the best seasons I have witnessed due to the length and consistency of dumps and top ups, but more importantly, there was virtually NO RAIN and below average temps which really helped to prolong the cover.

And of course there was the 2000 season......ahhh memories

A balance of good weather and tops ups does make for best skiing and also makes it easier on people who stay a week, less likely to get a bad weather week.

Yeh, I was thinking that; but the smaller values won't affect of the results as much, so I'm might just not butcher it. I might think about adding some kind of lift explanatory variable, i.e. 15/25 lifts open = good; 25/25 = excellent, maybe use some kind of ruff and ready dummy variable

ROFL.

Here is a chart set for Spencers Creek Snow Depths back to 1954.

It has 2 years to a chart.

I can't get it to upload to max allowed size in photobucket - if you want a better version of the chart PM me and I can email it to you directly.

Full Size Chart

I agree. Sorry re-read you original post and i got it wrong on first read.

Interesting to see that the snow from last week is still hanging around up top. A couple of pixs of the main range from today would be great to see. The Kosi Track cam at Thredbo still has plenty about. Another fall in the next week and there after might see it staying with patches all the way through. Temps are forecast to be low all next week. Shame Snowy Hydro didn't do a reading last Thursday - it would have averaged at least 2-5 cms on the measurement slope - as shown here from Wednesday at about 11am.

BOM released outlooks for May to July last week

Chance of exceeding median maximum temp


Chance of exceeding median min temp


Chance of exceeding median rainfall

IMO

Not liking daytime temps

IMO

looks warm

I read yesterday that despite the unseasonally cold weather we've just had, the BOM is expecting a drier and warmer winter. Here's hoping they are wrong!

Take graphics with a grain of salt. Temps only need to be 0.1 above the median.

But it does seem to fit with the SOI being negative (although it's only a bit). It's still technically in the "neutral" zone.





http://www.bom.gov.au/climate/enso/

BOM says in their chart of exceeding the long-term median minimum temperatures. How is this to be taken? Exceed is to go beyond, yet the median may well be a negative minimum temperature and therefore to exceed a negative would be simply to not reach the negative temp? For to exceed a negative, the exceeding value surely must be a greater incursion into the negative....too much coffee, that reads schite