From: ccasm@cc.newcastle.edu.au
Subject: Re: prediction
Organization: University of Newcastle, AUSTRALIA
Distribution: aus
Date: Mon, 17 Aug 1992 05:52:27 GMT

In article <2968@ariel.its.unimelb.EDU.AU
> david@mullara.met.unimelb.edu.au (David Jones) writes:
> 
>>In article <djm.713421735@phobos>, djm@kbs.citri.edu.au (David Mills) writes:
>>> Having just spent a week at Mt. Hotham, I'd have to say it is probably the
>>> worst snow cover I've seen in August, since 1982.
> 
>>Earlier this year I posted that I had observed a good indicator of the coming
>>snow season. This was based on moisture in the ground, or in this case the
>>lack of it - the drought is still widespread.
> 
> Although the snowfalls were fairly good (especially in May), these came from
> relatively warm events which served to wash away much of the snow they deposited
> leaving the slopes bare in all but the highest locations. As for heavy, the
> highest total reported in Vic. for May was 30cm, at Buller. This is by no
> means a heavy snowfall for Autumn, c.f. 30cm in April 1987, ~30cm March 1991
> ~40cm May 1987, 100+cm 1968. 
>

OK Perhaps not the best ever start. I wonder why? 
                        ^^^^            
 
> Despite the best attempts of numerous people I am firmly of the belief that the
> prediction of the Australian ski season is still not soundly possible. Although
> such things as Sea Surface Temperatures (critical for rainfall), and analogues
> with previous sequences of years may give hints, it appears that a given season
> is unpredictable. In general in Australia we have typically 5 or so average seasons
> followed by a bumper one, which is frequently followed by a poor one. This cycle
> is evident many times in the last few decades, 
> 
> c.f. 1964/65 1968/69 1972/73 1981/82, (if my memory serves me right)
> 
> with the swing from a bumper to a dud season commonly associated 
> with swings in the atmospheric circulation over the Pacific Ocean 
> associated with the El nino atmospheric phenomena. However
> this is not always the case as demonstrated by last years heavy season which 
> followed the good snowfalls of 1990, (a season arguably the heaviest since 1964). In fact
> despite large areas of Australia experiencing drought during Autumn and Winter 1991,
> (see the ~100 day period in Queensland without rain!!!), relatively local effects and
> a series of strong frontal passages resulted in the very heavy falls.

 My comment was on moisture IN the ground - this is quite different to
moisture ON the ground.  It also means a time frame of about 6 months - the
lead-time between moisture content and the possibility of snow.
 And I meant in the area of the Snowy Mountains. How can
Queensland rain be relevant? The dought broke in NSW.

> As for early snowfalls as predictors, look at the heavy falls in May 1982 for an
> example of when these fail. Conversely 1968 is an example of when a heavy fall 
> precedes a bumper season.

I agree. Look at this year. It clearly doesn't correlate.

> 
> The use of moisture in the ground at a given location would also have to be questioned. 
> The weather can and frequently is very different between given locations, especially
> if they are well separated. I use August 1991 as a prime example, Vic and Southern N.S.W
> were very moist while all of Northern Aust. and much of the central regions were
> ravaged by severe drought. As for very wet periods indicating heavy snow, June 1991
> was extremely wet through the SE and E regions of Aust. and yet the snowfalls were non
> existent. The converse was the case in May, when the region was very dry but saw some
> light snow and cool temperatures. 

The lead time is 3 to 6 months. Anyone can predict with higher degree of
accuracy what tomorrow is going to be like. I would like to predict what it
will be like when I BOOK a week at Thredbo, usually around Feb/March, not when
I actually go there, usually around end of July/early Aug.
 
The moisture content IN the ground at depth (say 1 metre or more) in March is
the clue, or so I feel, but I have no proof except observation.
 Obviously rain in July washes away the snow..
 ....I was there (Falls Creek) last year  :-(


> David.


Big Al.