Eastern Tasmanian forecast by Steve Shearer (issued Mon April 21st)

Features of the Forecast (tl;dr)

• Spike in short range S swell Tues with fresh S-S/SE winds
• Small blend of easing short range S and long period S swell wrap Wed with light winds
• Building NE windswell Thurs PM, extends into Fri AM
• Small blend of local NE and long range E/NE swells Sat under light winds
• S swell building Sun PM likely peaking on Mon
• More S swell next week

Recap

Large and powerful swells from the E/NE held in the 8-10ft range on Sat with offshore winds and a’noon seabreezes. Size dipped into the 4ft range on Sun and has decreased back to 2ft today under variable winds before a S’ly change. 

This week and next week (Apr 21 - May 2)

We’ve got a more subdued synoptic outlook this week with weak high pressure currently in the Tasman and a complex troughy area of low pressure situated off the Southern NSW/Gippsland coast. That trough moves NE, backed by a large high pressure centre currently in the Bight. We’ll see the trough bring S’ly winds and swell as it moves up the NSW Coast through the first half of this week. That will mostly obscure some traces of long period S swell pushing up the Tasman, generated by a large polar low. A distant low in the South Pacific currently in Tongan latitudes will send some small but good quality E’ly swell late this week, with more favourable winds. 

In the short run we’ll see the S’ly flow adjacent to Tasmania whip up fresh S-S/SE winds with some short range S swell to 3-4ft expected through the day, though with low quality.

Source of short range S swell tomorrow

Pressure gradients ease through Wed and as the high moves NE we’ll see early light SE winds shift to variable then NE breezes. Short range S swells to 2ft will be of similar magnitude to long period S swell wrap which offers up 2 occ. 3ft sets. 

Increasing N-NE winds Thurs will see some useful NE windswell build through the day, likely into the 2-3ft range along with some small S’ly swell wrap to 2ft. 

We’ll see those NE windswells hold into Fri morning before getting shunted away by a S’ly change and easing rapidly. 

Into the weekend and we’ll see a small blend of local NE and E/NE swells from the South Pacific offering up a 2ft wave with light winds. 

That will ease into Sun with a front pushing W’ly winds through. A new spike in S swell in the wake of the front will see S swells build to 2-3ft in the a’noon. 

Quite a complicated outlook for next week with plenty of model divergence so we’ll sketch out the basic outline and fill in the details as we get more model agreement. 

The weekend’s low looks to skip away quite quickly so easing S swells are on the cards for early next week. 

Another S’ly change is likely Mon or Tues as a front pushes through the  Tasman, backed by another strong high. We should see some S swell from this broad scale pattern, along with S’ly winds, possibly easing quickly as high pressure moves up over southern NSW.

Also in play is a potential E swell from a tropical low moving towards the North Island onto a pre-existing E’ly fetch. The pattern looks quite mobile at present, so no major size is expected but swell from the north-eastern quadrant looks likely as we move into the middle of next week. 

In other words, typical autumn pattern of medium size swells from the E and S- potentially combining with light winds.

We’ll pencil it in for now and see how it looks on Wed.

Seeya then.