A very large and powerful surf is expected to develop along the NSW Coast during Thursday leading to some beach erosion and dangerous beach conditions! Above image via Windy showing wave heights during the afternoon (red 4m+, pink 5m+, orange 6m+ white 8m+).
A very large and powerful surf is expected to develop along the Southern NSW Coast during the morning. Wave heights are expected to increase during the late morning and into the early afternoon across the Central Coast between Newcastle and Wollongong before increasing further across the Northern Coastal areas between Newcastle and the QLD Border during the evening and early night. Wave heights are expected to exceed 5m in many locations and potentially peak at around 7-8m for some areas, not including any rogue waves which could exceed 10m. These kinds of waves, whilst not overly rare for the NSW Coast during Winter.. are certainly dangerous though and this could lead to not only severe beach erosion for some areas that are exposed to the waves, but also become treacherous for anyone venturing into the water.
The reason why these waves are expected to develop is due to a strong low pressure system (979hpa) over near New Zealand interacting with a high pressure system (1028hpa) over Eastern Australia. The tight pressure gradient over the Tasman Sea is expected to coincide with strong to damaging South to South West winds impacting Coastal areas of NSW behind a cool change. As the change moves North during the day, the winds will continue to increase through any areas it moves through. This combination of pressure gradient and strong to damaging winds will be enough to produce dangerous sea conditions in the form of damaging gales (120-140km/h offshore, 70-100km/h over the exposed Coast) and powerful waves (5-7/8m, rogue waves up to 10m).