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Why does the wind shutoff like a switch?
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mkrasnoff



Joined: 10 Apr 2000
Posts: 154

PostPosted: Thu Jul 19, 2007 3:17 pm    Post subject: Why does the wind shutoff like a switch? Reply with quote

The wind cutoff very fast at Leo yesterday around 6:45.
It's happened before and I've always wondered why, sometimes as I'm swimming back to shore.
Did someone piss off the wind gods? A logical non-technical explanation.
I'm sure the same goes for other sailing sites. Kihei comes to mind for me.
You can be going balls to the wall on a 3.7 and then bam, the wind totally dies and you're chumming for tigers. Luckily it usually picks up again after a few minutes.

I'm sure it has something to do with the pressure gradients, the same reason why the wind bumped up so rapidly a bit past 5:00. See graph below.
I'm sure Mike Godsey has a logical explanation since he's a weather weanie.

Mahalo!



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jpbassking



Joined: 19 May 1998
Posts: 2386
Location: Leo

PostPosted: Thu Jul 19, 2007 3:33 pm    Post subject: Reply with quote

It seems to coinside with the exact time that DABUL sets foot in the water. Laughing
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jpbassking



Joined: 19 May 1998
Posts: 2386
Location: Leo

PostPosted: Thu Jul 19, 2007 3:35 pm    Post subject: Reply with quote

It seems to coinside with the exact time that DABUL sets foot in the water. Laughing
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isobars



Joined: 12 Dec 1999
Posts: 14339

PostPosted: Thu Jul 19, 2007 4:47 pm    Post subject: Reply with quote

Mixing.

You've got strong wind above, but it only intermittently mixes down to the surface. How steadily it mixes down depends on atmospheric stability; high stability promotes steadier mixing, especially during the heat of the day. Low stability mixing is subject to every passing cloud and invisible thermal bubbles, creating more gustiness. Any practical weather book, especially one about sailing weather or wind in particular, will have whole chapters on this topic. Mixing can be nonexistent or incredibly inconsistent when a lake is colder than the air by 20 degrees F or more; we've often sat at a lake with wind measured at 30-40 kts just hundreds or maybe even scores of feet overhead while we had zero breeze or even opposing 10 mph beneath the scudding clouds.

\m/
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mkrasnoff



Joined: 10 Apr 2000
Posts: 154

PostPosted: Thu Jul 19, 2007 4:52 pm    Post subject: Reply with quote

.

Last edited by mkrasnoff on Sat Feb 07, 2009 9:11 pm; edited 1 time in total
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jpbassking



Joined: 19 May 1998
Posts: 2386
Location: Leo

PostPosted: Thu Jul 19, 2007 5:00 pm    Post subject: Reply with quote

Perhaps we all need to get out of the water when we see him rigging up. Shocked
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swchandler



Joined: 08 Nov 1993
Posts: 5908

PostPosted: Thu Jul 19, 2007 7:35 pm    Post subject: Reply with quote

It's really quite simple, as the wind went downslope (NW) in the very late afternoon along the south facing coast below Point Conception. In doing so, it cuts off the flow to areas much further south.

Because of these conditions, I sailed really powered at El Capitan State Beach til sunset. Very strong 5.6 conditions. It's been my secret spot for many years. I've tried to explain the setup to many locally in Santa Barbara over the years, but they lack the focus and a greater sense vision to take advantage of the possible opportunties that can present themselves quite suddenly late in the day. I guess the lack of wind reporting station leaves most in the dark about what really happens.
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dabull1



Joined: 19 Mar 1997
Posts: 525

PostPosted: Fri Jul 20, 2007 2:32 am    Post subject: Reply with quote

Yeah guys, take up that collection and just send me to Maui!!! However I did set a new world distance record for body dragging a couple of weeks ago at lower Kanaha after a turtle borrowed my fin about a mile and a half from shore. A session just isn't a session for a diehard Leo guy without dragging or swimming it in! Bull
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blond_wind



Joined: 20 Jul 2007
Posts: 18

PostPosted: Fri Jul 20, 2007 7:29 am    Post subject: Luckly Reply with quote

Uaaaaau.You are very lucky. You live near a windsurf spot with 30 wind nods. I live in north of Italy in Europe and there are in Italy only two windsurf spot with strong win. There are Sardinia an island and Garda Lake. I live in north of Italy Milan. I work there. I haven't the sea only in the week end it will be possible have a windsurf session...and in this last week end the wind wasn't enough. I am thinking to move in other continent with wind all the year.
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jpbassking



Joined: 19 May 1998
Posts: 2386
Location: Leo

PostPosted: Fri Jul 20, 2007 9:23 am    Post subject: Reply with quote

Well then come on out to California, I think Bull is single.
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