Pristine days with light W’ly winds for the most part lay ahead. The tropical low over the North Island has rotated out of the swell window, dissipating quickly as it did so. We’ve still got some fun E’ly quadrant swell inbound from that source before a period of quiet surf becomes established over the weekend.
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We’ve got a nice chunky 1033 hPa High slow moving at very southerly latitude, roughly triangulated between Tasmania and the South Island. As well as a precursor SE fetch adjacent to the South Island it is now squeezing pressure gradients with a compact, but deep low, which is currently forming gale force fetches out of Cook Strait and just north of the North Island.
No major changes to the weekend’s trend outlook, though wave heights have been nudged up a little given the size and strength seen later today.
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.
More fronts maintain a synoptic offshore flow for the week and we’ve got plenty of S swell to last the week, albeit at reduced sizes compared to the weekend.
More fronts maintain a synoptic offshore flow 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 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.