Woo! New site is online - select here to use it!


Forums > Kitesurfing General

Southerly theories, where's the Freo doc gone?

Reply
Created by eppo > 9 months ago, 24 Nov 2012
eppo
WA, 9793 posts
24 Nov 2012 10:37PM
Thumbs Up

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?

beefarmer
WA, 328 posts
25 Nov 2012 12:21AM
Thumbs Up

i've always had this idea we never did get many of them... mostly ssw'ers

'cause thats what we always seem to get in perth.

but the BOM 3pm summer average wind rose for perth seems to indicate otherwise so guess i need to get my compass out one of these days




or maybe you're onto something eppo!

Elroy Jetson
WA, 706 posts
25 Nov 2012 12:44AM
Thumbs Up

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.



suniboy21
VIC, 1090 posts
25 Nov 2012 7:30AM
Thumbs Up

The problem lies with the daylight savings, see if WA had that extra hour of sun light the heat from the sun would push the wind more onshore.
But seems like your more worried about your curtains faiding!

Weta
WA, 893 posts
25 Nov 2012 6:37AM
Thumbs Up

Vote +1 Daylight Savings

Sonyiboy for premier

gesper
NSW, 518 posts
25 Nov 2012 9:39AM
Thumbs Up

Many moons ago the centre of the Highs used to cross Australia at latitudes around Shark Bay WA to around Gold Coast in the east and at times you would see 1 high pressure system that covered the whole of Australia .Havent seen them that high up for at least 15 to 20 years.They seem to be crossing from around Perth to Sydney now.
Perhaps with them being so low the winds are predominantly from the south

eppo
WA, 9793 posts
25 Nov 2012 7:41AM
Thumbs Up

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.

moons
WA, 349 posts
25 Nov 2012 8:22AM
Thumbs Up

Hey Eppo,
Did you get out yesterday

birdie919
WA, 82 posts
25 Nov 2012 9:28AM
Thumbs Up

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!!!

beefarmer
WA, 328 posts
25 Nov 2012 10:31AM
Thumbs Up

suniboy21 said...
The problem lies with the daylight savings, see if WA had that extra hour of sun light the heat from the sun would push the wind more onshore.
But seems like your more worried about your curtains faiding!




that logic would be right up there with that of our current batch of politicians, so yeah i second that, sunniboy for premier. at least he reads the kite forums

Zed
WA, 1274 posts
25 Nov 2012 10:39AM
Thumbs Up

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.


eppo
WA, 9793 posts
25 Nov 2012 2:14PM
Thumbs Up

moons said...
Hey Eppo,
Did you get out yesterday




Nah I have strained an intercostal muscle Farq it!! You??


Looks like the circus is upon us. 20 odd windsurfers from Avs doing there traditional straight line tracking dance.

whatthe
WA, 186 posts
25 Nov 2012 8:21PM
Thumbs Up

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

moons
WA, 349 posts
25 Nov 2012 8:22PM
Thumbs Up

eppo said...
moons said...
Hey Eppo,
Did you get out yesterday




Nah I have strained an intercostal muscle Farq it!! You??


Looks like the circus is upon us. 20 odd windsurfers from Avs doing there traditional straight line tracking dance.


Yep, there was more traffic on the water than on the road

eppo
WA, 9793 posts
25 Nov 2012 8:29PM
Thumbs Up

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.

eppo
WA, 9793 posts
25 Nov 2012 8:30PM
Thumbs Up

moons said...
eppo said...
moons said...
Hey Eppo,
Did you get out yesterday




Nah I have strained an intercostal muscle Farq it!! You??


Looks like the circus is upon us. 20 odd windsurfers from Avs doing there traditional straight line tracking dance.


Yep, there was more traffic on the water than on the road





Yep the circus is in town for sure. All the way from Perth and it troughs out and turned easterly. Sucked the Farqed in. Lol.....

moons
WA, 349 posts
26 Nov 2012 9:11AM
Thumbs Up

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

austin
671 posts
26 Nov 2012 9:22AM
Thumbs Up

suppose its time to move up north then

Triggerhappy
WA, 174 posts
26 Nov 2012 9:53AM
Thumbs Up

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.



Subscribe
Reply

Forums > Kitesurfing General


"Southerly theories, where's the Freo doc gone?" started by eppo