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windfind
Joined: 18 Mar 1997 Posts: 1901
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Posted: Thu May 02, 2019 11:33 am Post subject: Where is the NPH and our NW wind? |
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Hi Gang,
I am getting a lot of emails basically asking "What happened to the North Pacific High this season and where are our NW ocean winds that make our spring winds"
Actually, the North Pacific High is still along the west coast. It is just in the "wrong" place for spring.
As you can see in the animation below there is a large strong North Pacific High but in recent weeks it has been centered well west of Canada and the Pacific Northwest. Typically, the NPH would be spending more time west of the Bay Area throwing NW wind at our coast.
The NPH's location this spring means it is creating N-NNW wind just off our coast. This direction along with the lobe of low pressure you see in the animation helps stir up the eddy you can see west of the Bay Area.
If you have ever watched any eddy, from a dust devil to a tornado, you know they move around and gain and lose strength randomly.
https://www.youtube.com/watch?v=AwKc7H5gIWo
Our eddies are far larger and slower moving than a dust devil but they have still been making forecasting very difficult since a change in location and strength of the eddy midday can change the winds for each site especially near shore. And frequently we have had more than one eddy this season. So we are struggling to do the best forecasts possible.
If you are a newcomer to the Bay Area you should be aware that until recent years we and all the models were completely unable to even forecast the development of these eddies. This often led to wildly inaccurate forecasts where fog and SW winds would "magically" appear overnight shutting down the coast and parts of the Peninsula while bringing unexpected strong wind to sites north of the Bay Bridge. Now, it is rare for us to miss an eddy and slowly we are improving our forecasts during eddies.
So anytime you see the word eddy in a forecast you should use your knowledge of local fog patterns mid-afternoon to fine-tune the forecast especially for the winds near shore since the eddy may have moved since our 11:30 update.
Looking at the animation notice where "our" NW wind has been located so often this season.
Mike Godsey
iwindsurf.com/ikitesurf.com
Weatheflow.com
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