Western Australian forecast by Steve Shearer (issued Fri March 14th)

Features of the Forecast (tl;dr)

• Large SW groundswell likely later Fri, peaking Sat AM with S-SE winds
• Easing swells Sun with offshore winds all day
• Plenty of mid-sized swell next week with good winds
• Likely down a notch Tues, back up Wed
• More mid-sized pulses into Thurs/Fri
• Likely a notch bigger into next weekend
• Indian Ocean remains active with bigger swells likely medium term

Recap

4-6ft surf between the Capes yesterday with 2ft surf at Perth/Mandurah under variable winds as a trough hovered offshore. There were periods of both onshore and offshore winds and surf was mostly glassy/lumpy under this variable flow. Similar winds this morning although now tending more NW as the trough of low pressure remains offshore. Size has eased to 4-5ft between the Capes, 1-2ft in Perth/Mandurah. Winds are expected to tend SW-S as the trough finally moves eastwards under the state. There’s no sign of a new groundswell in the water or on the wave buoys but it’s expected to fill in this evening and overnight.

Winds tended more N'ly as trough approached

This weekend and next week (Mar 14 - 21)

Not much change to the outlook. 

Swell filling in overnight will supply plenty of energy for the early with size to 6-8ft and bigger sets on the bommies in the SW, smaller 2-3ft in Perth/Mandurah. Winds will have some S’ly component likely mod strength S’lies tending S/SE through SE in the a’noon as high pressure starts to slide under the state later in the day. Size will slowly back down in the a’noon but still with strong sets. 

Winds tend offshore through Sun as strong high pressure ridges in under the state. Plenty of clean surf in the 3-5ft range for the morning, 2ft in Perth/Mandurah with a small reinforcing pulse holding waves heights at similar levels after a brief easing trend.

As stated on Wed, the Indian Ocean is quite active with a long fetch of W’ly gales currently SW of the state (see below) and moving E. That will supply reinforcing pulses of SW swell later in the weekend into Mon before a temporary easing into Tues. Size in the 4-5ft range is expected in the SW, smaller 2ft or less in Perth/Mandurah. Offshore E’ly winds remain through Mon, tending more S’ly Tues then S/SE’ly Wed as another large high approaches the state. 

A compact  low tracks NE towards the state Sun/Mon bringing an increase in new SW swell late Tues into Wed, with surf rebuilding into the 4-6ft range in the SW, 2-3ft in Perth/Mandurah.

Winds should be favourable offshore as a new high slides into and under the state- likely E/SE-SE tending more E’ly on Thurs.

More moderate sized SW swells into the end of the week with a trailing fetch of W’ly gales behind the low adding plenty of background energy into Thurs/Fri.

A compact mid-latitude low fires up Wed/Thurs likely to supply a bump in size Thurs, against the backdrop of residual swell from the SW. 

The long fetches trailing these low disturbances will maintain plenty of energy through next week, likely building again into Fri and next weekend.

A more significant storm looks to track under Heard Island next weekend suggesting more substantial groundswell into next week.

There’s still considerable model divergence over the timing of these swells so check back in on Mon and tune into the latest update with Craig back from leave.

Until then, have a great weekend!