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Eddy today: this is starting to eat into my water time!
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windfind



Joined: 18 Mar 1997
Posts: 1899

PostPosted: Thu Jul 28, 2016 7:43 pm    Post subject: Eddy today: this is starting to eat into my water time! Reply with quote

Hi Gang,

It has been a crazy hard forecast season so far. Endless eddies have threaten the coast and sometimes the Peninsula winds most days.

Take a look at the satellite imagery today of the eddy. Notice the southerly flow and the fog patterns.

Now take a long look at the crazy spiraling of the winds in the eddy zone near the coast. Imagine trying to forecast how that crazy wind flow will impact every site in the Bay Area each eddy day.

Today I did a decent job with the wind forecast for most sites. But I would like to whine a bit.... this season it is taking me almost twice as long, about 1.5 hours, per forecast to do a decent job. Good thing I like intellectual challenges and have a thick skin. But this is starting to eat into my time on the water which is a serious issue...

Mike Godsey
iwindsurf.com/ikitesurf.com
Weatheflow.com



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paulbroder



Joined: 20 Jun 2000
Posts: 23

PostPosted: Thu Jul 28, 2016 9:29 pm    Post subject: Reply with quote

Mike,we really appreciate all the effort you make to forecast accurately. We know you are doing your best in a new environment of climate change. Keep it up, but don't miss out on any sailing days; we'll get along.
Thanks,
Paul
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justingordon



Joined: 04 May 2002
Posts: 148

PostPosted: Fri Jul 29, 2016 7:20 pm    Post subject: And over on Maui Reply with quote

Nonstop tradewinds and much smaller summer swell on Maui this summer.

Related?
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windfind



Joined: 18 Mar 1997
Posts: 1899

PostPosted: Sat Jul 30, 2016 10:57 am    Post subject: Re: And over on Maui Reply with quote

justingordon wrote:
Nonstop tradewinds and much smaller summer swell on Maui this summer.
Related?


Hi Justin,

Good to hear from you after so long.

Yes, implausible at it may seem, there is a correlation between the frequent eddies off the Bay Area and strong trade winds in Hawaii.

Both occur when there is a large North Pacific High at the surface AND there are frequent upper troughs at ≈ 18,000 ft. passing just north of the Pacific Northwest. (like the one today creating crazy strong winds in the Gorge this afternoon)

When this occurs the North Pacific High usually extends a ridge towards Canada as you can see in the image below for today. This in turn does 2 things:

1. It pushes the North Pacific High's eastern trade winds closer to Hawaii as you see in the image.

2. The ridge makes the North Pacific High's winds near the west coast turn NNW rather than the "normal" NW. This in turn favors the creating of the eddy you see in the image and in reality today west of the Bay Area.

This is probably related to the Pacific–North American teleconnection pattern (PNA) and reflects climate related variables.

The related and bigger question is why eddies near the Bay Area, which used to be uncommon, have become increasingly frequent in the last decade. And that is related to the increased amplitude and frequency of summer upper troughs. And that, I would guess, is related to the changes in the Polar Vortex which in turn is related to ice patterns in the Arctic. But I am venturing further and further away from my narrow field of expertise.

Mike Godsey
iwindsurf.com/ikitesurf.com
Weatheflow.com



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motogon



Joined: 19 Aug 2000
Posts: 376
Location: Philly

PostPosted: Sat Jul 30, 2016 3:27 pm    Post subject: Reply with quote

What is "eddy"?
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Andrew
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A lot of great surfers were ruined by family and steady job.
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airwave



Joined: 29 Jun 2000
Posts: 386

PostPosted: Sun Jul 31, 2016 12:05 am    Post subject: Reply with quote

Windfind,
Thanks for your help.
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beallmd



Joined: 10 May 1998
Posts: 1154

PostPosted: Sun Jul 31, 2016 2:17 pm    Post subject: Reply with quote

I do appreciate the forecasts and always look at them, but (there's always a but huh?) the Rio sailing was treated to some very nice wind the last 2 days with yesterday hitting Epic on the scale. The dam broke! The heat from the east bay all the way to Reno sets up a massive dam which blocks the wind from coming on in. Then at some point the dam breaks and the flood of wind comes in. The epic Gorgekeley event a year or two ago was an excellent example. We all remember the awesome video of the fog forming at the gate and rushing in to the east bay by way of Berkeley. We drove across the bay bridge on the way to Rio and it was awesome, even frightening! Sherman absolutely nuked for a couple of days combined with a strong ebb, whew! So I am guessing it is hard to predict when the dam will break. I don't know if all super highs and heat waves are followed by big winds through Sherman but it seems right.
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beallmd



Joined: 10 May 1998
Posts: 1154

PostPosted: Sun Jul 31, 2016 3:15 pm    Post subject: Reply with quote

While I'm asking questions, let me ask another weather question I've wondered about for a long time. maybe it's simple but I can't figure it out. If hurricanes form and draw their strength from warm water, usually 82 degrees and above, and lose strength and dissipate over water below that temperature such as the northern Atlantic or if they move north in the pacific, how do winter pacific storms form and gather strength? Sometimes they use the term winter hurricanes but obviously that's not right. Thanks
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daKine



Joined: 23 Aug 2006
Posts: 39

PostPosted: Sun Jul 31, 2016 4:20 pm    Post subject: Re: And over on Maui Reply with quote

justingordon wrote:
Nonstop tradewinds and much smaller summer swell on Maui this summer.

Related?


I'm calling BS on that.
It is true it is marginally better than the last two seasons but it is still lame compared to the days when you could sail 4.5/5.0 for 10 days in a row.
The tropical storms keep coming and each one messes with the trades for several days.
Why else would folks like Hot Sails be making lots of 6m wave sails?
Maybe La Nina will shut down the tropical storm conveyer someday but not yet!
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windfind



Joined: 18 Mar 1997
Posts: 1899

PostPosted: Sun Jul 31, 2016 8:02 pm    Post subject: Reply with quote

Hi DaKine,

The discussion was just about this season especially recent weeks. Justin did not appear to be talking about the strength of the trade winds compared to past years but rather their recent improved frequency.

I totally agree with you that the Trade Winds in recent years are much weaker and often less frequent than they were in past decades. This change is well documented in the meteorological literature. The recent changes in the North Pacific High's position have produced just a slight improvement.

The same northerly positioning of the North Pacific High I discussed is also allowing tropical storms to move across the pacific towards Maui. I did a blog a few weeks back about that very issue.

Mike Godsey
iwindsurf.com/ikitesurf.com
Weatheflow.com
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