A broad region of troughiness stretching from the Tasman Sea through the Coral Sea over the weekend will coalesce into a major sub-tropical low off New Zealand’s North Island, on Monday.
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The Southern Ocean gyre is now well to the S and SE of the South Island, generating one last pulse of long period swell for our region. There’s a fresh set of cards to sort through next week with a couple of swell sources on offer. Read on for details.
More fronts maintain a synoptic offshore flow (or light winds) for the week and we’ve got plenty of S swell to last the week, albeit at reduced sizes compared to the weekend.
Current ASCAT (satellite wind speed) passes show gales to severe gales extending down to 55S with a tighter core of storm force winds just emerging from behind Tasmania as it tracks NE into the Tasman Sea. The synoptic flow from the fronts and Southern Gyre remains W to W/SW and that will continue all weekend with plenty of wind chill to boot.
Strong high pressure support from a 1033hPa elongated high in the Bight is providing tight pressure gradients for the multiple fronts spinning off the gyre. That will lead to numerous over-lapping S’ly pulses over the coming week with a general step-ladder effect expected at least through to Mon. A general offshore flow will accompany these pulses as the fronts drive W’ly biased winds across the temperate to sub-tropical East Coast.
A strong node of the long wave trough is steering fronts into the Tasman Sea while a negative phase of the SAM (Southern Annular Mode) is bringing the southern Ocean storm track into a more northerly latitude, closer to the Australian continent and Tasman Sea. Both those factors will drive a series of strong cold fronts this week, with a step-ladder effect likely as each subsequent front works on an already charged sea state.
Using today's results in Southern NSW as a proxy, we should see some solid south swell across Northern NSW on Saturday.
Brisk westerly winds and a complex low pressure gyre in the Tasman Sea, with multiple cold fronts and a deep S’ly fetch of gales extending down to 55S have ushered in the first day of Winter.
Another dynamic week ahead but a bit more straightforwards in the sense that all the incoming swell will be from the S- once the current E swell pulse peters out fully through tomorrow.
Right on cue, as head into the first week of winter, a nice cold outbreak and blast of W’ly winds with accompanying S’ly swells affects the entire East Coast.