The Outlook | Influence of SAM slipping

Influence of SAM slipping


Top Stories
Aa

THERE has been minimal change in the long term indicators in the past weeks with the newly analysed Southern Annular Mode being active in producing strong westerly winds and snow in south-eastern Australia.

Aa

THERE has been minimal change in the long term indicators in the past weeks with the newly analysed Southern Annular Mode being active in producing strong westerly winds and snow in south-eastern Australia.

The SAM’s influence will decrease in the coming week and a more typical spring pattern will develop by mid September. 

Overall a neural pattern is likely to persist in both the Pacific and Indian Oceans for at least the next six months and - as indicated previously - this creates problems for long range weather forecasting. 

In the past long term neutral patterns mean slightly below average spring and early summer rainfall in NSW, but there is also the increased opportunity for the occasional one off event bringing brief but worthwhile rain to some parts of the star at different times. 

So overall the chance of sprung rainfall exceeding normal is only 35 per cent inland, but 55 per cent on the coast and in the north-east of the states because it is in these areas that one off events are slightly more likely to occur. 

As indicated previously it is more likely - about an 80 per cent chance - that spring and early summer temperatures will exceed the long term normal. 

Sunshine hours and evaporation levels are also likely to exceed normal and also on the downside, the chance of severe storms in late spring is a little higher than normal. 

Along with this there is also a slight increase in the chance of hail on the ranges and in the north east. 

While the neutral pattern persists the longer term assessments for 2018  remain fairly speculative.

Aa

From the front page

Sponsored by