Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Friday 20th February)

Best Days: Should be good waves most days, although actual size is still unsure (peak expected late Sun and Mon). Winds should generally be good.

Recap: Quality E/NE swell with generally good winds. 

This weekend (Feb 21 - 22)

It’s been a very active week of weather in the north, and some changes in the evolution of Severe Tropical Cyclone Marcia have resulted in a delay and slight downgrade in the weekend surf forecast. 

On Wednesday, the general consensus was that the developing Tropical Low in the Coral Sea would merge with a trough off SE Qld on Thursday, before running parallel to the Northern NSW coast through Friday and Saturday. 

This hasn’t quite happened (yet) - the Tropical Low quickly exceeded intensification expectations, with the now widely reported Cat 5 TC Marcia moving a little more slowly in its southward track (with a coastal crossing this morning near Shoalwater Bay, on the Capricorn Coast of Central Queensland). It's expected to weaken as is moves overland before then pushing off the SE Qld coast on Saturday afternoon. 

STC Marcia is still then expected to consolidate within the trough offshore from the Qld/NSW border but its future movements from there are still not particularly clear. The latest model guidance is still (!) divergent on where the low will track, however what is clear is that the low will probably remain at least a little more north in latitude than Wednesday’s expectations - if not a lot more north. It’s also evolving more slowly than initially thought.

That being said we should still see some developments within our NE swell window over the coming 24-36 hours. Saturday will probably remain similar to today with a steady supply of moderate NE and E/NE swell somewhere between 3ft and 5ft at exposed NE facing beaches (smaller at south facing beaches). Winds are expected to be light to moderate NE all day (possibly variable for periods) so conditions should be pretty good. 

Sunday is where we’re likely to see a slightly bigger pulse of NE swell from the reformed TC Marcia off the  Northern NSW coast early Saturday. Early morning is expected to be similar to Saturday (3-5ft at NE facing beaches) but we should see a boost towards 5-6ft through the mid to late afternoon.

However, both this size increase and also Sunday’s local wind regime is highly dependent on how and where this system tracks.

Based on the current data, we’ll see a freshening SE winds during the day (nothing too strong, but enough to cause some bumpiness) however there is a chance for an upgrade above the earlier forecast size - but if this happens local winds may be a little stronger. In particular if the GFS solution were to eventuate we’d probably be looking at 8ft+ sets late Sunday or Monday but this model has been slowly edging away from a big southern NSW swell event over the last 24 hours, so my confidence is wavering.

Is there a chance for a downgrade? Yes, it certainly couldn't be ruled out (for the late Sun/Mon pulse) but that would require a major about-face in the model gudiance over a very short time frame.

As such, it’ll probably be worth an interim update on this sometime later Saturday - I’ll mention anything relevant in the comments section below.

Next week (Feb 23 onwards)  

With reduced confidence for Sunday’s pulse - at just 48 hours in advance - we’re really at the mercy of the models for the long term forecast through next week.

Best estimations at the moment are for Sunday’s late pulse to maintain 5-6ft waves at NE facing beaches through Monday, before easing slowly through Tuesday and Wednesday. I'll update in the comments below if there are any major upgrades or downgrades. 

Persistent trade activity north and north-east of New Zealand should ensure a steady supply of E/NE swell in the 2-3ft+ range for the second half of the week right through into the weekend. 

Otherwise, despite the suggestion for a few new sources of swell in the long range, it’s probably better to wait until Monday when we’ll have a lot more clarify on the situation. Have a great weekend! See you Monday.