Western Australia Surf Forecast by Steve Shearer (issued Wed October 20th)

Best Days: Sat and Sun morning are the only windows of favourable winds amongst the onshore flow

Features of the Forecast (tl;dr)

• Easing swells Thurs with W’ly winds abating
• Large SW groundswell Fri, easing Sat window of good winds Sat morning
• Small leftover Sun morning with good winds AM
• Another round of stormy, onshore surf likely from Tues next week as mid-latitude low approaches region

Recap

Victory at sea conditions have become established over the last 24-36 hrs as a complex low pressure system has smashed into the south-west.  Onshore surf built rapidly in size yesterday, as winds tended NW and became gale force, and today has seen a storm surf in the 10ft range at exposed coastlines between the Capes, with smaller stormy surf in the more sheltered Mandurah to Perth stretch of coastline. Strictly lay days unless you were mad keen ands willing to take on a Perth groyne to find some rideable shape in amongst the maelstrom.

This week and weekend (Oct 18 - 24)

The low has now passed through the area and is weakening in the Bight, with a long trailing fetch of W’ly winds bringing continued onshore conditions as local storm surf slowly eases back through tomorrow. W’ly winds and easing size will make finding a rideable wave tricky. A weak ridge developing over the Gascoyne is expected to only slowly move south so the South-west division is likely to remain a mess through tomorrow. Expect easing surf in the 6ft range between the Capes with smaller 2-3ft surf in Perth, slightly larger in Mandurah.

We’re still on track for another strong pulse of SW swell generated by an intense low which flared as it formed near Heard Is, reaching peak intensity as it tracked between 90-100E. This system is currently weakening as it begins to track below the state. Winds unfortunately remain poor as the system is embedded in the long wave trough with a node aimed up into WA.

Expect size in the 8ft range in the Margaret River area, grading smaller 4ft in Mandurah and 3-4ft in Perth. A light S’ly flow down south, may tend more SE in Perth, opening up some sheltered options around the Capes. Winds will tend W’ly through the day, laying down through the a’noon hours as pressure gradients ease. Plenty of lump and bump is likely to remain anywhere exposed to the SW Indian Ocean.

Windows of offshore winds now present both Sat and Sun mornings as a weak high slips below the state, setting up a weak and transient E’ly flow with a coastal trough extending from the Gascoyne bringing a light/variable onshore flow in the a’noon. As that trough moves inland on Sun a W’ly flow becomes established again through the South-West of the state.

We’ll be on the backside of the Friday swell through Sat, with easing 4-5ft sets in the morning at exposed breaks between the Capes, smaller 2-3ft in Mandurah and 2ft in Perth. Best conditions early with light offshores, though a residual lump may be present from Friday.

Sunday sees smaller 3ft surf in Margaret, 2ft on Mandurah and 1-2ft in Perth.

Onshore winds re-establish on Mon as another mid-latitude low approaches and tips the state. This will not be as severe as the current system but will see onshore winds from the SW establish through Mon, with a slight increase in swell from both the approaching front and more distant fetch. To be honest the week looks ordinary with surf in the 3-5ft range during Mon from an earlier incarnation of the low, holding around that size through Tues and Wed but with a lingering onshore flow it won’t be anything pretty. Smaller 2ft surf in Perth will be likewise marred by onshore winds. Not a great week by any means.

Longer term and the Indian Ocean enters a more dormant phase next week. A large high in the Central Indian Ocean suppresses the storm track, through the favourable part of the WA swell window, suggesting small surf going into next weekend and early week beginning Nov1.

Winds do begin to tend more favourable SE by next weekend as high pressure slips below the SW of the state.

Check back Fri for a fresh update.