Anyone have a theory as to why we seem to be getting more south in the winds in WA. The old south wester seems to be rare? Lot of southerlies turning offshore between 5 and 6. Any theories from you meteorological gurus?

Could it be that alot of us grew up frequenting the beaches between Cottesloe and Hillarys Marina and learned to associate that West was straight out to sea?

Then we got older, life happened, and we moved away to the north or south of Perth. Upon heading down to the new local beach we instinctly still expected West to be straight out to sea.

Example: A SW'er would be sideshore in Falcon and nearly directly onshore in Yanchep.

Vote +1 Daylight Savings

Sonyiboy for premier

Yeh my suspicions are with the last post to I have noticed the highs coming through more south in the past few years.

Down here the south westers aren't cross shore really, still cross on, albeit not at the same angle as up at scabs etc.

But have noticed in the past 3 to 4 years, more south south wests, turning increasingly more south in the later afternoon, then switching offshore. The switch off shore always happened, but it seems to be doing it earlier and earlier in the day. Ask the crew at Avalon yesterday, how they faired.

But this is all anecdotal or empirical observations have nothing to confirm this.

dont get me started on daylight saving.... have you got an hour!!!! freekin dogwalkers, chilhood obististy, the 4 oclock bird call!!!!, hot driving to work......shall i go on!!!

interesting theories! I've been sailing this spot for the last 20 odd years and to get out the back there is a small gap in the reef maybe 15 - 20m and you can only just make it, launching from the same spot next to the groyne. I've never really been able to get upwind of the gap, which would be the case if there were more southerlies.

Two things come to mind: Coriolis Force and proximity to shore.

I got out my copy of Stuart Walker's "The Sailor's Wind" (1998) which says the following regarding the Freo Doctor:

Offshore at Fremantle the initial direction (between 1300 & 1600) of a typical sea breeze is 230deg. Its initial speed may be from 3 to 12 knots. It gradually strengthens until by evening it has reached its peak velocity, which varies between 12 and 28 knots. As it increases in velocity, it backs (due to the Coriolis Force) from approx. 230deg to 200deg to 180deg or even 170deg and flows parallel to the coast.

A wind blowing oblique to a shoreline will tend to blow more perpendicular as it hits the shore. Thus a SSW 200m offshore will veer to SW near the shore (where the wind is measured).

Regarding the location of highs, Walker says:

Centres of high pressure pass to the south of Fremantle in summer...

I don't think they ever passed north of Perth (32deg lat) in the past, as they are caused by the global pressure belt phenomemon, see en.wikipedia.org/wiki/Horse_latitudes

whatthe said...
Two things come to mind: Coriolis Force and proximity to shore.

I got out my copy of Stuart Walker's "The Sailor's Wind" (1998) which says the following regarding the Freo Doctor:

Offshore at Fremantle the initial direction (between 1300 & 1600) of a typical sea breeze is 230deg. Its initial speed may be from 3 to 12 knots. It gradually strengthens until by evening it has reached its peak velocity, which varies between 12 and 28 knots. As it increases in velocity, it backs (due to the Coriolis Force) from approx. 230deg to 200deg to 180deg or even 170deg and flows parallel to the coast.

A wind blowing oblique to a shoreline will tend to blow more perpendicular as it hits the shore. Thus a SSW 200m offshore will veer to SW near the shore (where the wind is measured).

Regarding the location of highs, Walker says:

Centres of high pressure pass to the south of Fremantle in summer...

I don't think they ever passed north of Perth (32deg lat) in the past, as they are caused by the global pressure belt phenomemon, see en.wikipedia.org/wiki/Horse_latitudes

That was a cool reply man. Anyhow blew sw today! There goes my theory.

^^^ The wind dropped off, so I came in, went to Singleton and the wind was cranking. I got worked over by some big dumpers

whatthe said...
Two things come to mind: Coriolis Force and proximity to shore.

I got out my copy of Stuart Walker's "The Sailor's Wind" (1998) which says the following regarding the Freo Doctor:

Offshore at Fremantle the initial direction (between 1300 & 1600) of a typical sea breeze is 230deg. Its initial speed may be from 3 to 12 knots. It gradually strengthens until by evening it has reached its peak velocity, which varies between 12 and 28 knots. As it increases in velocity, it backs (due to the Coriolis Force) from approx. 230deg to 200deg to 180deg or even 170deg and flows parallel to the coast.

A wind blowing oblique to a shoreline will tend to blow more perpendicular as it hits the shore. Thus a SSW 200m offshore will veer to SW near the shore (where the wind is measured).

Perfect answer and correct.