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. Compared to Fridays model runs the fetch now is a little more mobile, weaker and rotates faster out of the swell producing phase, which will see a bit of a downgrade. Still some good waves on offer though.

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. 

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.

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.