I have been commissioned here on a very lucrative contract (straight out of the Wild Brumby distillery) for regular weather & climate updates & timely alerts of significant winter weather events.
If you get any alerts a day or two after the freshies just remember there’s no friends in powder & send all correspondence immediately to Pieta at MRBC. Please.
She will reply to you all personally within 12 hrs even if it’s dumping and the surf’s pumping.
So rather than doing an out and out prediction for the winter (as you likely already have read the Grasshopper and the other croaky something something I forget….) let's start with the basics of what drives our climate , and we can progress from here as we get into the season and the topic that really matters.
Warning !!! You may learn something here if you’re not careful.
You can even ask questions , c/- Pieta…., if you like .
If I don’t know the answer I will make something up.
OK. The Australian climate is largely influenced by temperature patterns in the Pacific and Indian Oceans.
The Pacific Ocean is illustrated with the Nino 3.4 outlook, and the Indian Ocean by the Indian Ocean Dipole (i.e IOD) .
Both these models are trending into the Positive which means that the general wind direction (and moisture) from the sea surface over these oceans is being drawn away from Australia. i.e El Nino and Postive IOD.
The sea surface heat & moisture rises in the Eastern Pacific ( North/South America) & West Indian Ocean (Africa) causing the prevailing winds to flow towards these warmer waters. It’s called Atmospheric Convection and is illustrated in the images below.
**Please understand the model outlooks that are generated in Autumn have a lower accuracy than at other times of the year.**
We all know how much r@#n we got, when the moisture from the Indian Ocean was regularly drawn down to the Alps (see previous page & Northwest Cloudbands in image below).
Then it was the guessing game when the cold fronts/freezing air would arrive relative to when the moisture would arrive.
Remember when Perisher all but disappeared underwater one afternoon, Guthega Rd and the Alpine Way washed out…
Another event again we got the early moisture then a severe drop in temps, the roads all snap-froze and it was carnage from the resort carparks back to Jindy (except for the tow truck drivers who loved it with $500 each recovery)
Flipside we also got the cold air before the moisture a few times and then it was game on in the trees for those lucky to be on the spot. How sweet that was ;-) !
Some punters called it THE best quality ever in Oz. Big call , but true enough.
Quite simply it really is that fickle.
The Southern Annular Mode (SAM), also known as the Antarctic Oscillation (AAO), describes the north–south movement of the westerly wind belt that circles Antarctica and directs our winter weather from the Southern Ocean across the Great Australian Bight and ideally toward the Australian Alps.
The changing position of the westerly wind belt influences the strength and position of these cold front storm systems, and is an important driver of rainfall variability in southern Australia.
In the Positive phase the band of westerly winds contracts toward Antarctica (see Summer Sub-tropical Ridge above), and we get the dreaded blocking high pressures over southern Australia which usually relate to stable, dry conditions.
The big storms get pushed below us and we get the relatively warmer moisture from the Tasman Sea pushed back onto the East Coast.
In the Negative phase the band of westerly winds expands towards the Equator ( see Winter Sub-tropical Ridge above) , so more (or stronger) low pressure systems are able to push up over southern Australia which may likely mean increased storms , & colder air ideally loaded with moisture i.e. Snow !!. Bring this on //.
At this stage the AAO is trending towards the Negative phase as is what you would expect as we transition from Summer to Winter .
To be sure,
We are going to get snow ( I strongly doubt we’ll see 2.0m. )
Some systems will be sweet as , some not so… business as usual in Oz.
Regardless we are going to have fun playing on and in it.
It will be another great winter in the mountains with MRBC !
Ski Heil !