Eastern Tasmanian Forecast by Steve Shearer (issued Friday August 8th)

Features of the Forecast (tl;dr)

• Small to tiny surf this week ahead of a N/NE windswell Fri
• Small S swell Sat 
• Stronger s swell developing Sun PM with fresh SW winds
• Sizey S swell developing Mon as low forms in Tasman
• Easing swells Tues
• Uncertain outlook medium term with unstable Tasman- check back Wed for latest updates

Recap

Only small E swells to 2ft on Sat, fading out Sun with a small S/SE swell to similar size. Today started small with a small NE windswell building this a’noon under freshening NE winds.

This week and next week (Aug 11 - 22)

Another unseasonal low pressure system formed off the QLD coast over the weekend and has now drifted over to a position roughly equidistant between New Caledonia and the North Island. It continues to drift eastwards through the short term. A large high sits well down in latitude (south of the South Island) for this time of the year, with a moderate E’ly fetch through the South Pacific slot. Pressure gradients are easing short term as the New Zealand high drifts away but we have another strong high currently moving through the Bight expected to bring S’ly winds with a chance of a low pressure trough forming in the Tasman in advance of the ridge. Frontal activity looks to follow closely behind bringing S swells over the latter part of the weekend. Once again, we’re in a position of enhanced instability in the Tasman and Coral Seas with models really struggling to resolve the troughiness. It’s likely we’ll see more E’ly swells medium term although with model skill so impaired we’ll need to accept lots of short term revisions as we move through the week. 

In the short run, current N/NE winds shift N/NW to NW tomorrow and small NE windswell hovers in the 2ft range- just workable for the keen.

Minor swells less than 2ft then pad out Wed and Thurs with variable winds - NW tending S’ly on Wed and trending back NW again on Thurs.

The next swells look to fill in Fri with pre-frontal N’ly winds whipping up NE windswell to 2-3ft during the day (see below) and winds shifting N/NW-NW in the a’noon.

Source of NE windswell Fri

We’ll see a weak front Sat with not much swell.

A secondary front Sun looks stronger and should see a late a’noon spike in S swell under fresh W/SW tending SW winds.

The weekend’s fronts and lows sweeping up from the south look to consolidate early next week into a much stronger system, backed by a strong high in the Bight. Good odds we’ll see S’ly gales off the coast Mon, with a strong response in the form of robust S’ly swells developing  provisionally up into the 4-6ft range at S facing beaches easing into the a’noon.

Size then eases Tues into the 3-4ft range before easing as the low moves away and winds lay down as high pressure moves over NSW. 

Plenty of uncertainty after that. 

GFS has suggested we may see a deep trough form off the NSW North Coast or SEQLD region with a strong E/NE-NE infeed into it - a version of a black nor-easter. Latest runs have gone off the idea but we’ll flag it for now just in case it does eventuate. 

EC has a more conventional, conservative outlook with the high lingering in the Tasman and low pressure slowly weakening as it drifts over New Zealand. We’d see fun, easing S through SE swells under this scenario. 

A very dynamic outlook for mid-August, so expect revisions and check back in Wed to see how it’s shaping up.

Seeya then!