This anchored trough fetch, or trough block pattern is favourable for swell production for almost the entire Eastern Seaboard and will come with mostly offshore winds until the weekend brings a more S’ly biased flow to Tasmania. We’ll see remnants of a small low at the terminus of the trough get captured over the weekend and generate S swells from the return flow of a regenerated low.
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An inland trough eventually clears the coast later Tues or Wed and the broad E’ly infeed into the trough transforms a typical but out of season tradewind fetch into a more broadscale “trough block” feature which will send swell to most of the Eastern Seaboard.
This looks to set-up as the clearing trough Mon sets up a long N-S oriented line in the Tasman to Coral Seas and focusses a long E’ly tending E/NE fetch through this vast area focussing nicely into the NETas swell window around a small low at the end of the trough.
A low in the Tasman is moving north away from the East Tas swell window with some strong, zonal frontal activity tracking through the deep southern ocean. An active July map, with more action ahead next week.
Although S’ly winds will be problematic until Fri there’ll some swell to play with as low pressure remains in the Tasman, with a slingshot fetch expected as the low moves N during the week and some sideband energy for NETas.
A deepening mid-latitude low moving across us will bring some northerly windswell followed by short-range southerly energy.
By Sun morning we should see a low NW of Tas with a secondary system further away in the Tasman towards the South Island.
Models have been flip-flopping but we are starting to have some confidence on a frontal system and the cut-off low entering the Tasman this weekend or early next week.
Winds may shift more N’ly through Bass Strait and up towards the South Coast later Thurs into Fri, bringing a spike in NE windswell.
Winds feeding into the southern flank of the low are well aimed at Tasmania and we’ll see more strong SE tending E/SE swell tomorrow.