Sydney Hunter Illawarra Forecast by Steve Shearer (issued Mon July 15th)

Features of the Forecast (tl;dr)

• E swell holding in there at lower levels, with a small pulse later Tues into Wed
• Stronger S’ly swell spike building Wed with winds freshening from the SW
• S swell holdings into Thurs AM before easing, winds improving through the a’noon
• Another S swell spike Fri with offshore winds
• Easing surf Sat with offshore winds- late S swell spike possible 
• S swell Sun with offshore winds
• Easing S swells Mon next week
• Surf likely to go tiny/flat with hard W’ly winds next week

Recap

Solid, pumping surf over the weekend as the trough block E/NE swell came in hot and was joined by return flow S swell as a low which formed in the trough line close to the coast moved southwards towards Tasmania. How big? Easy 6ft+ on Sat with some 8ft set reported under mostly mod/fresh SW winds. Size held into Sun morning, with just a slight easing through the day (still bombing sets!) under a more favourable W/SW flow. True offshore W’ly winds today with a cold outbreak reaching right up into sub-tropical/tropical latitudes. Still firing this morning with a blend of E/NE and S swells to 3-5ft and the S component expected to ease out during the a’noon.

Pumping barrels Sun for the early

This week (July 15-19)

As mentioned above we have a deep low (985hPa) adjacent to Tasmania and another attached low centre further E in the Tasman with the long E/NE infeed into this complex low gyre focussed near the west coast of the North Island and slowly sliding out of the swell window. As we discussed last week the return S’ly flow from the low actually pushes onto the western side of Tasmania, effectively out of our swell window. We will see the low eventually move NE and back into our swell window by mid week with a spike in S swell expected during this period with a brief interruption of a mostly W’ly flow to a fresh SW-S/SW one. We’ll then see more bog standard fronts with smaller S swell pulses into and over the weekend. Read on for details. 

Straight offshore winds tomorrow with a smaller signal of E’ly swell. We should still get a slight bump in size through the a’noon from a last flare up in the fetch near the North Island building back to 3ft+ on the sets. Generally smaller and slower 2 occ. 3ft in the morning but everywhere should be well groomed by the offshore so well worth a look.

Wed looks vigorous with the low moving NE and a slingshot fetch of S’ly quarter winds (see below) pushing up the southern/central NSW Coast. Early winds from the W-W/SW will quickly tend SW and ramp right up, possibly tending more S/SW later in the day. E swells to 3ft will be the dominant swell for the dawny with a new S swell spike quickly building mid morning- reaching 6-8ft at exposed breaks by mid arvo. Winds will be a problem for straight S facing  beaches with smaller surf into more protected locations.

S swell holds in there at elevated heights Thurs morning although down a little from Wednesdays heights as the fetch rapidly moves up and away. Expect 4-6ft of size in the morning with lumpiness and bump from SW-S/SW winds. We should see an improvement  in conditions as another front pushes through, with winds likely to tend more W/SW later in the a’noon. There may be a period of light/variable winds prior to the frontal wind change. 

Offshore winds all day Fri with the passage of the front and a high up over northern Australia supplying W’ly ridging. We’ll see another spike in S swell from the fetch in the lower Tasman. Models seem to be overcooking this swell in comparison to modelled windspeeds but size should at least push back up to 3-4ft (5ft on the Hunter) across S and SE exposures. 

This weekend (July 20-21)

Another frontal passage due Sat. We may see some pre-frontal NW winds develop before winds shift more W’ly at mod/fresh paces. Fridays' pulse eases off from 3ft down to 2ft or less. Depending on the timing of the front we may see either surf become tiny late in the day or rebuild late with a new S pulse (Sunday is a better bet). 

Fresh S swell for Sun. Again, it’s quite a transient fetch so wave heights are likely duration limited but we should see surf from dawn in the 3-4ft range again, a notch bigger on the Hunter under offshore winds. Expect an easing trend in the a’noon.

Next week (July 22 onwards)

Quite an unusual pattern next week with large low pressure gyres developing E of New Zealand and to the south of the continent. That puts the Tasman Sea in the “dead zone” in between these large storm systems. As a result we’re likely looking at a period of offshore winds and tiny/flat surf developing next week. 

We should see some small S swell leftovers for Mon in the 2ft range with offshore winds.

By Tues it looks like we’ll be down to knee to ankle high surf with the flat spell likely to persist into the end of the week. 

We’ll keep our eye out for traces of long period S swell but absent that looks like a period of no surf ahead next week.

Likely this flat spell will be broken from the S into the weekend 27-28/7 as the next frontal passage pushes into the Tasman. That’s too far off to have any confidence in specifics so check back in Wed and we’ll see how the long range is looking. Still plenty to keep us occupied in the short term.

Check ya Wednesday.