A stalled trough off the coast is expected to muscle up through Thursday (see below), strengthening E/SE winds into the Far South Coast, before a Tasman Low forms along the trough line overnight Thursday, and drives southerly gales across all Southern NSW coast regions into Friday morning.
Strong high pressure moves E to be well south of the Bight by mid next week. An intrusion of cold air is expected to form an upper cold pool, leading to instability and the development of a surface low as the upper trough interacts with the Tasman trough, later Thurs or Fri. There’s a possibility this low may be an ECL or have characteristics similar to one, potentially including severe weather.
High pressure is now drifting over New Zealand with multiple trough areas through the Tasman Sea, interior, and extending along the East Coast from the tropics down to temperate NSW. This is creating a moist, variable, onshore flow through the region with small surf.
We’re right up to our neck in a troughy La Nina pattern, which continues on through this week. High pressure is sitting just to the East of Tasmania, with the dissipating remains of the weekend’s trough of low pressure linked to a coastal trough extending up into the sub-tropics
The long, elongated trough line extending off the NSW Coast and angling in a NW/SE orientation towards New Zealand is now located a bit further north than modelled on Wed.
Lots of S quarter swell and wind from the same direction this weekend. With the trough extending out from the NSW South Coast towards the South Island, and a long fetch of S/SSE gales developing through the lower Tasman, there’ll be no shortage of size.
Our current unstable, stormy pattern is being driven by a peanut-shaped high straddling Tasmania, and multiple troughs of low pressure, stretching from the interior of NSW, out to the Mid North Coast and South Pacific near New Zealand’s North Island.
The pattern as we described it on Wed remains fundamentally the same, but the position of the moving parts has shifted so there’s some significant changes to the weekend f/cast.
Weak fronts are below the country and an inland low is tracking across from WA, tied to the continuing pattern of interior troughiness which is associated with a developing La Nina pattern. This pattern, which has been with us for most of the last few weeks, is expected to see continuing small, flukey swells into the medium term.
A deep mid-latitude low with high pressure support in the Bight and multiple cold fronts has now moved E of Tasmania with W to SW gales pushing out of Bass Strait and a deeper SSW fetch pushing up from the Southern Ocean into the Tasman Sea. It’s a wintry looking system and it has a nice sting in the tail as a small troughy intensification slingshots up into the Tasman Sea through tomorrow, giving another longer period pulse S swell to add onto the main body of the swell.