Eastern Tasmanian Forecast by Steve Shearer (issued Mon 19th May)

Features of the Forecast (tl;dr)

• Small long period S swell Tues with offshore winds
• Tiny Wed with offshore winds
• Small increase in E/NE swell Thurs, stronger Fri and peaking Sat as trough/low drifts south through the Tasman
• Easing swells Sun into Mon
• Strong S swells likely next week, Tues/Wed at this stage

Recap

Tiny surf Sat morning before an increase in S swell which held in Sun morning in the 3ft range under mod S winds before easing into today and being replaced by a small E swell to 1-2ft under offshore winds.

This week and next week (May19— May 30)

A very unstable, dynamic synoptic chart in the Tasman this week with a large high (1034hPa) moving from the Bight through Victoria, with a coastal trough deepening on the leading edge of the high directing very moist onshore winds across Central NSW, extending up into the sub-tropics. We still have some model uncertainty over the fate of this trough. Fridays forecast of a low or ECL variant was downgraded into a persistent trough over the weekend but there are still model runs suggesting a low or (more likely) multiple embedded lows will form in the trough line this week. These small lows may move north, then east and finally south or may coalesce in a more classic Tasman Low or ECL variant. Either way we should see some quality E/NE swell for Tas as the fetch draws out through the Tasman. With so much uncertainty still around be prepared for major revisions as we move through the week. This is a nightmare to forecast!

In the short run we’ll see NW winds as the high moves NE of the state and zonal winds pass under the state. Small long period S swell offers a 1-2ft wave at S exposed beaches.

Couple of tiny days follow that with offshore winds and barely rideable surf, at least for Wed. 

Thurs looks a little better with swell from the fetch in the Tasman starting to filter down in the 2ft range. Light winds tend N’ly as a trough moves NE of the state.

By Fri we should see a bigger increase in E/NE swell as the Tasman Sea fetch either gets dragged southwards or tilts in a more favourable direction for Tas (see below). Expect some revisions in size and timing but we should see a more significant swell in the 3ft range.

Fetch being dragged south into Tasmanian swell window

The weekend has potential for even bigger surf, if certain model runs hold true. 

If the trough/low moves south, it will drag the fetch right into the prime swell window for NETas  and we’ll see surf in the 5-6ft range Sat, easing a notch Sun. 

Into next week and That's likely to be strongly overshadowed by strong S swells as a front and parent low moves aggressively into the Tasman early next week (see below).

Too early to have confidence in size or timing but early indications are looking like it will be significant S swell event, likely developing Tues/Wed. 

Lot’s of short em uncertainty to get through before then so check back Wed and keep tabs on below the line comments as we track this dynamic Tasman Sea weather event. 

Seeya Wed!