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 on swell pulses as each subsequent front works on an already charged sea state.
Sunday’s NW quadrant wind trend will be related to an advancing frontal progression across the south-eastern corner of the country, associated with an amplifying Long Wave Trough.
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 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 is headed our way.
Synoptic pattern still has a ground-hog day feel to it, with a large, slow moving high inching it’s way across the Tasman and a coastal trough lying parallel to almost the entire East Coast. Change is on the way though.
Sub-tropical troughs and the remnants of TC Gina near New Caledonia are maintaining a deep E’ly flow through the Coral Sea while the last in a series of powerful cold fronts are now sweeping up past the South Island of New Zealand with small S to SSE swell pulses to come over the next couple of days from this source.
The frontal progression responsible for the S swell pulses over the last couple of days is now on the New Zealand side of the Tasman, with a large high approaching Tasmania setting up a firm ridge along the coast.