Eastern Tasmanian Forecast by Steve Shearer (issued Wed Jan 8th)

Features of the Forecast (tl;dr)

• Small NE windswells building Thurs and peaking over the weekend
• Small into next week with minor NE windswell Mon/Tues
• Another spike in NE windswell likely Wed
• Possible S swell as front and low move into the Tasman, check back Fri for latest

Recap  

Small S/SE swells to 2ft yesterday under moderating winds have continued into today with light winds now tending N’ly and freshening. 

This week and next week (Jan8- Jan17)

A small trough of low pressure has stalled off Seal Rocks with a SE infeed south of the trough expected to ease over the next 24 hrs and a light/variable flow north of the trough. Meanwhile a high pressure cell is moving E of Tasmania, developing a N’ly flow. This is expected to generate a persistent NE windswell, peaking over the weekend. 

In the short run we’ll see winds shift N, tending NE in the a’noon with some small NE windswell developing to 1-2ft in the a’noon.

Similar size and winds for Fri, although windspeeds may even be less.

High pressure moves near the South Island and a broad inland low will see winds freshen from N-NE over the weekend, with NE windswell building Sat, up into the 3-4ft range.

Source of NE windswell Sat/Sun

We should see size extend into Sun before easing slowly during the day with NE winds shifting more variable as a trough moves across the state.

Weak high pressure in the Tasman and a variable- N-NE flow to start next week as a trough lingers about the Island. A couple of days of small surf are expected.

We may see another pulse of NE windswell as winds freshen again in response to an approaching front and low. 

From mid-week we are likely to see a shift as the inland low gets absorbed into a frontal system and low moving from the Bight into Bass Strait (see below). That should see a SW-S change and S swells as frontal winds from that direction operate on Tasman seas. Still some model divergence with EC suggesting a stronger low moving into the Tasman with a larger S swell from Fri next week.

GFS suggests a more standard frontal system which moves across the Tasman and generates a spike in S swell Thurs, possibly hanging out in the Tasman as a broad low which may generate workable S swells into next weekend.

Too early to have any confidence in specifics, especially with weak high pressure support expected.

That pattern of weak high pressure and transient lows or troughs in the Tasman does look to continue in the medium term suggesting more small, weak surf as our summer of discontent drags on.