Repost::
Physical oceanographer
On the swells direction :
" around *287.5, degrees
then jumps/spikes to *319
and *343 degrees or so ."
*important ! See compass .
Rottnest island doesn't create a major swell shadow on Cottesloe beach during west-north-west swell events .
At rare times most likely in winter the waves will go above 2-3 metres at cott & metro beaches .
So far during 2017 , there has not been a swell event in WA as big as the event 17-19 june 1988 !
Indicating just how rare it is ,
It may not occur every year .
This was a remarkable swell event way back in june 17-20th june .
Plus in the early AM hours of the 22nd june another dangerous swell event was recorded with a massive 22 second period.
Although not tall, these waves were moving twice the average wave speed . These conditions are the deadly type of waves that wash rock fishermen into the ocean / & drowned .
Articles links have been supplied about this.
http://www.websleuths.com/forums/showthread.php?p=13393864
http://www.websleuths.com/forums/showthread.php?p=13393776
"Swell was quite west as expected " quote po
Cottesloe beach geographical location is exposed to swells from this direction ie ; Swell angle of northwest :
Physical oceanographer
On the swells direction :
" around *287.5, degrees
then jumps/spikes to *319
and *343 degrees or so ."
*important ! See compass .
Cottesloe beach geographical location is exposed to swells from the Swell from the northwest :
These swells may be truly from a west or wsw direction .
They then refract around the Northside of Rottnest .
The west side of Rottnest was 5 metres decreasing and a few hours later cott educated guess ; 2.5 metre because;
The swell was able to bypass around the northside of Rottnest island .
Rottnest doesn't create a major swell shadow on Cottesloe beach during west-north-west swell events .
Wave height and power is lost as the swells travel over shallow water .
This is called 'wave attenuation due to bottom friction'
Only at rare times will the waves will go above 2-3 metres at cott metro beaches .
So far during 2017 , there has not been Any swell event in WA as big as the heights recorded 17-19 june 1988 ! (according to dotr buoy data)
It may not occur every year , this was a remarkable swell buoy reading .
http://www.websleuths.com/forums/showthread.php?p=13393992
During the time frame of 1am - until mid morning on the 20th june the waves would still have been big (for cott standard) imo .
Theres also a window during the early morning hours on the 22nd june that the waves may have had the power to damage, accident or drown whatever etc it may have been .
swimming conditions were fine on the 21st absolutely.
See link and graph of the frequency ,
This is when a 'long period swell' arrives
