Sydney Hunter Illawarra Forecast by Steve Shearer (issued Wed Sep 24th)

Features of the Forecast (tl;dr)

• Sizey mid period S swell Thurs, with reinforcing long period swells filling in later 
• Long period S swell persists Fri
• Great winds Thurs and Fri for S facing reefs and beaches- mostly W/NW-NW
• Persisting S swells into Sat, easing Sun with light winds- tending SE on Sun
• New S pulse Mon 
• Tricky, troughy pattern early next week but light winds Mon, tending N’ly Tues looks likely 
• More S swell next week

Recap

A strong S’ly surge up the coast whipped up sizey S swell yesterday in the3-5ft range with semi-clean conditions early under W/SW winds, becoming more wind affected as winds clocked around S/SW-S through the day. Size has ramped down quickly into this morning with an easing  3ft of swell under light offshore breezes which tend to light S/SE-SE breezes through the day. 

Clean leftovers from yesterdays spike in S swell

This week (Sep 22-26)

Strong high pressure is moving up over the continent and rapidly weakening as it becomes a typically mobile high for this time of year. It’ll move into the Tasman at sub-tropical latitudes through tomorrow with a slow moving polar low positioned in Tasman sea longitudes directing powerful frontal passages into the southern swell window. While these fetches are more directly aimed at Pacific targets we’ll see plenty of long period S swell wrap through the short term into the weekend. Next week is still looking a bit troughy in the Tasman but models have backed off any significant low pressure development so the active frontal systems we’ve seen so far this spring look set to cotninue as our main swell source.

In the short run we’ll see winds shift W/SW through W’ly tomorrow, possibly even with more W/NW tilt as high pressure moves up over the continent. A powerful frontal passage currently slingshotting NE into the Tasman past Tasmania generates plenty of mid period S swell for tomorrow, likely up in the 4-5ft range with bigger 6ft sets on the Hunter and other S swell magnets. That source eases through the day with longer period S swell trains filling in through the a’noon and supplying 3-4ft surf with outliers possible at deepwater adjacent reefs and bommies.

Long period S swells persist through Fri as a very stormy sea state remains active below Tasmania. All day NW winds look primo for S facing beaches and reefs. Size should persist in the 3-4ft range with some deepwater adjacent reefs hoovering up extra size- don’t be surprised if some of these spots are significantly bigger.

This weekend (Sep 27-28)

High pressure stays up in the sub-tropics, drifting eastwards with a cut-off low approaching from the west. That will hold a W/NW tending NW’ly flow, likely to veer more N/NW-N through the day. Still favourable for S facing beaches and reefs. Still some swell leftover for Sat from the slow moving polar low with 3ft sets (still some 4ft sets at the Hunter and other magnets) but we’ll see swell periods drop down with size and power easing through the day. 

Still some S swell to 2-3ft into Sun from a lingering fetch in the far southern Tasman. Another front passing over Tasmania should see winds from the NW tend W then W/SW. A curve ball from a small, troughy area off the Central coast may see winds shift SE through the a’noon. 

Next week (Sep 29 onwards)

Sundays frontal passage looks a notch stronger today, provisionally pushing wave heights back into the 3 occ. 4ft range at S facing beaches (bigger on the Hunter) into Mon. Winds look a bit tricky due to the lingering trough but pressure gradients look slack so winds should be light- land breezes tending to SE-E breezes as weak high pressure moves into the central Tasman.

A trough or inland low approaches and shifts winds to the north Tues before the trough or low enters the Tasman Wed with winds dependent on where the trough or low ends up. 

A series of zonal fronts then push across Tasmania with W’ly quadrant winds and small swells although models are suggesting a pulse Wed- we’ll see how that looks Fri, latest runs make that look less likely.

The last of the series may bring a sizier S swell over the weekend 4-5/9 or into the next week if EC has the more accurate rendering with the front penetrating further north into the Tasman with a broader fetch below it. 

We’ll flag that for now and see how it looks Fri.

Seeya then.