Autumn: Why It's The Surfers Season
Autumn is the surfers season. After months of weak, onshore summer swells, anticipation rises as the seasons tick over. The days get shorter, winds stay offshore into the afternoon and the water temperature is usually warmer in than out. Weather charts get checked daily for the possible formation of East Coast Lows or tightly packed isobars throughout the Southern Ocean in the hope of pumping autumn surf.
We're coming out of one of the strongest La Nina signals on record this summer. Basically, stronger than normal easterly trade winds throughout the Equatorial Pacific Ocean have pilled up warm water in the Western South Pacific Ocean and Coral Sea. As a result sea surface temperatures (SST's) throughout the Coral and Tasman Seas are two degrees above average, while off the West Australian coastline, they are three degrees above average.
With all this warm water sitting off our East and West Coasts, the shift towards the cooler seasons may prove to be quite interesting. As we move deeper into autumn, cold air masses will be projected up from the Southern Ocean to more northern latitudes. The interaction between the warm air above the warm seas and the cold polar air in the upper atmosphere often results in the development of stronger cold outbreaks and intense low pressure cells if the synoptic setup is favourable.
There are no hardened facts pointing to the increased likelihood of swell producing systems as a result of a warmer than normal sea surface temperatures, but the potential is certainly there. One thing to think about though is that the sea surface temperatures were similarly above average in the Tasman Sea last year, and as we saw, it proved to be quite an average season of waves.
Still, the house is well and truly in order and anticipation levels are high. Only time will tell if autumn 2011 becomes one of the benchmark seasons for swell.//CRAIG BROKENSHA