An easterly trough low looks to deepen over the Tasman Sea this coming week, which is good news for big wave chasers along the NSW coast. As a trough moves offshore on Monday, a defined low pressure system will form and deepen moving into Tuesday. Models indicate the system has the necessary characteristics to form into a strong offshore mid-latitude cyclone - that being low pressure at the surface and upper atmosphere as well as a stubborn high pressure system over New Zealand forcing the low to hang around over the Tasman Sea. As with any of these complex systems, models differ in strength and location accuracy. Although most models agree a strong low will form, the European model, ECMWF, has pressure as low as 985hPa early Wednesday morning, indicating powerful winds near its core. Sustained winds greater than 90km/h are likely should the ECMWF forecast come to fruition. This is bad for anyone sailing across the Tasman but great for experienced surfers looking for big waves at protected spots along the east coast of NSW. Hanging mainly far off the southern NSW coast, the low looks to slowly make a circle over the Tasman in a clockwise way on Wednesday and Thursday, held there by the New Zealand high pressure system. This in turn creates a long fetch and time for big waves to form. By Wednesday, waves in the 6-8 foot range should be pounding the coast, with southwesterly winds. There is uncertainty as to whether the large waves will continue into Thursday as some models have the low moving away quicker than others. Either way, this type of surf-producing storm is unusual for this time of year, so no complaints from surfers. It will also be dangerous for activities like rock fishing so take precautions to stay out of trouble.