Western Australian forecast by Steve Shearer (issued Wed March 12th)

Features of the Forecast (tl;dr)

• Reinforcing SW groundswell building later Wed, peaking Thu
• NE tending variable then NW-W winds Wed
• Period of NE winds still possible Thurs depending on trough of low pressure off SW corner
• Variable tending S/SW-S winds Fri
• Large SW groundswell likely later Fri, peaking Sat AM with E/SE winds
• Plenty of mid-sized swell next week with good winds

Recap

Fun sized swells to 3-4ft between the Capes yesterday with surf to 1ft or so in Perth/Mandurah. Conditions were clean under light offshore winds and light/late seabreezes. Similar winds today with slightly less swell, although we have seen a minor increase into the a’noon with sets to 4ft.

Great conditions for the dawny

This week and next week (Mar 12 - 21)

Not much change to the outlook. Severe gales currently well to the SW of the state supply the next pulse of groundswell due in  Fri and peaking Sat.

In the interim we’ve got some smaller background swell which filled in this afternoon holding 4ft sets into tomorrow across the SW corner, smaller 1ft or so in Perth/Mandurah. Local winds will be tricky tomorrow as a trough of low pressure moves off the SW corner. We should see light onshore breezes but a period of variable or even NE breezes is possible around lunchtime before wind shift SW in the a’noon. 

Tricky winds again on Fri as the trough forms a small low and hovers off the SW coast. NW breezes are most likely tending mod/fresh W then SW in the a’noon but we may see periods of lighter/variable breezes in the morning depending on the positioning and movement of the low. 

Surf to 3-4ft in Margarets, 1ft or less in Perth/Mandurah with long period forerunners filling from mid-late morning then a bigger pulse to 5-6ft before dark. 

The bulk of the swell in the 15-17 second period fills in o/night Fri into Sat with sets in the 6-8ft range and bigger 10ft on Bommies with 3ft surf in Perth/Mandurah. Winds on Sat look to be S’ly, tending S/SE’ly leaving plenty of S’ly drift on the swell. They may tend more S/SE-SE’ly in the a’noon as high pressure approaches the SW of the state. 

By Sun winds will be offshore and should remain E-E/SE for most of the day. Plenty of clean swell in the 4-5ft range in the SW, smaller 2ft in Perth/Mandurah.

Into next week and a long fetch of gale force winds in the screaming 50’s later this week supplies plenty of energy into next week, although nothing major. The position of the long wave trough favours Victoria as those winds form low pressure and aim up more directly at SE Aus. 

We’re expecting plenty of fun sized 4-5ft surf for the SW into Mon with offshore winds, smaller 2ft in Perth/Mandurah. 

Surf eases Tues then a new pulse fills in Wed. 

These pulses will be overlapping and more of a subtle up and down in the surf as overlapping swell trains ease and fill in.

Winds look good Tues and Wed morning with offshore breezes and seabreezes as high pressure fills in under the state.

More swell incoming as the Indian Ocean starts to adopt a muscular winter-style pattern although the storm track is still relatively low, allowing good winds for SWWA.

Swells look moderate and consistent right through the end of next week. 

We’ll dial in specifics further on Fri.