Weather Conditions for Blue Mountains
cold weather that brings snow to the Blue Mountains usually comes from the
frontal systems that develop in the Southern Ocean. As a general guide, it
would be reasonable to say that most fronts approach from a south-westerly
direction. Usually, you would expect maybe two or three of the coldest
fronts each year to penetrate northwards beyond the ski fields and bring snow to the Blue Mountains. Sometimes, like the winter of 2000, you can get half a dozen
stronger cold fronts making it this far north.
Whilst the south-west
is the most common direction for cold fronts, its the ones from the south
that can be exciting. When the winds blow from this direction, they are
not obstructed by any high mountains like the winds are that come from the
south-west and west. For example, if you have a snowy front approaching
from the south-west/west, it has to be lifted over the mountains in the
Oberon area. This often has the effect of wringing the clouds dry of
most of their moisture (snow) as the Oberon ranges enhance uplift from the lower ground immediately to the west, so there isn't always much left for our area. Anyone who has made a quick trip out to the Oberon area during a cold snap can vouch for the amount of snow they can get out there! This is not to say we cannot get good snowfalls in a westerly or south-westerly weather pattern if upper levels are very cold and there is enhanced convection, its just less likely under most conditions. South and south-easterly cold fronts can also produce an improved moisture environment via the Tasman Sea.
So, look out for cold fronts approaching from the south or even the south-east on rare occasions. It's not often that these will be cold enough or moist enough but when they are...be prepared. And if you really like a long shot, look out for cold pre-frontal north-westerly cloud bands but thats another story.