Category: Puget Sound

West Coast Wind Blog: North Pacific High brings NNW wind to the Sea of Cortez…Not!


The winter 2019-2021 season in Baja was atypical in a number of ways.

It started off with a bang in November but from that point on the winds were often unreliable unless you were on foils or big kites or sail. Or if you were there during one of the few strong wind periods.
But the main anomaly was the source of the northerly winds. Typically much of the wind comes from high pressure in the Great Basin or ideally 4 corners area of the western USA. This wind streams towards the persistent low pressure trough south of Baja. Then this N to NNE winds curves into the beaches at places like La Ventana and Los Barriles that have a warm valley inland.

But often this year the Great Basin was devoid of high pressure so we often lost that wind machine. But weirdly the North Pacific High as unusually large and atypically in a more northern location much of this winter. And this often brought solid NW wind to Baja’s Pacific side and NNW winds to the Sea of Cortez.

Unfortunately, NNW winds are at a more unfavorable angle to the La Ventana and Los Barriles and especially the El Sargento beaches. Plus some of this wind can is west enough to come down the arroyos creating weak offshore W. winds at the beaches making for unreliable wind inside. Still, any wind was welcome this season and we became to learn the routine: Strong NW wind on the Pacific side of Baja means somewhat unreliable but welcome wind for the El Sargento to Los Barriles corridor.

Until….. it doesn’t. If the models are right later this week a resurgent North Pacific High brings strong NW winds to Southern California and the entire Pacific side of Baja.

Looking at this animation you can see the North Pacific High and those strong NW winds. But notice how weak the winds are in the Sea of Cortez.

Now notice the huge low pressure in the Great Basin. This is the area where we need HIGH PRESSURE to created classic El Norte winds for Baja.

Now notice how the North Pacific High curve towards the Great Basin low pressure rather than building down the length of the Sea of Cortez. Hence the exception to rule about NW wind on Baja’s Pacific side and a windy Sea of Cortez for the El Sargento to Los Barriles corridor.

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West Coast Wind Blog: While Baja’s big wind machines idle… back up wind engines carry the load.

by Mike Godsey

In normal years the bulk of the strong wind at the kite and windsurf sites in the Los Barriles and La Ventana areas comes from high pressure in the Great Basin area of the USA. However, the 2019-2020 winter season has seen lots of days when an unusually robust North Pacific High (NPH) has sent strong NNW winds down the Sea of Cortez.

The NNW angle of this NPH wind is not ideal for reliable wind at the beach but if there is good inland valley heating this wind does curve into the beaches.

But sometimes this season both the North Pacific High and the high pressure in the Great Basin have either been absent or too far away to help the Baja Sur winds.

Typically when this happens and we have blue skies we see kiteable mid to upper-teens winds from the local sea breeze as the inland valleys heat. These winds usually are strongest in the Rasta Beach area north of El Sargento and weaker for the La Ventana beaches and weaker yet for Los Barriles.

But there is another wind machine in our area that can ally with the local sea breezes to brings upper-teens to about 20 winds to the area. And that is the thermal trough just south of Baja’s East Cape.

Let’s look at today, February 21, 2020 as an example of this pattern.

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West Coast Wind Blog: Baja calm today, strong winds tomorrow… why?

by Mike Godsey, mikeATiwindsurf.com

Many years ago I spent 3 months per year doing underwater research on Pomacentrids around the islands of the Sea of Cortez. One thing that always struck me was how incredibly fast the weather could go from calm to strong winds.

The next 24 hours will brings such a change as this you can see in this graphic:

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West Coast Wind Blog: Anatomy of a likely big Baja El Norte wind event next week

by Mike Godsey, mikeATiwindsurf.com

Do you like gambles? So here is a big meteorological gamble. Today Dec. 1, 2019, I am forecasting a big El Norte winds event for the entire Sea of Cortez for Monday, Dec. 16. Normally I would not stick my neck out so far but this is a major event and the upper-level steering winds seem promising. I could be a day or so off on this forecast. And, as always, we need good sunshine in the inland valleys to create the local pressure gradient to suck those El Norte winds reliably to shore. But my bet is still there are strong winds.

Why? Follow this animated graphic carefully a few times and you will see the recipe for a big El Norte blow.

1. Note the isobars around the North Pacific High and the NW winds it is creating near the California coast.

2. Notice how there is low pressure in the Great Basin so there are few isobars near Baja’s Sea of Cortez

3. This produces very WEAK large scale winds for La Ventana and Los Barriles. There may be weak local sea breezes as the inland valleys heat.

4. Next is a critical step. Watch as a lobe of high pressure extends from the North Pacific High towards the Great Basin and

5. Watch the high-pressure move into the Great Basin as it enlarges steadily.

6. Notice how the low pressure exits to the east.

7. Now watch the Great Basin high pressure become stronger with more isobars moving towards Baja.

8. Watch isobars stack up over the Sea of Cortez

9. Watch El Norte winds fill in down the Sea of Cortez towards La Ventana

10. With high pressure ruling the Great Basin and 4 corners we see several days of El Norte winds if the clouds over Baja’s East Cape are not too thick.

 

 

 

 

 

 

 

 

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West Coast Wind Blog: Here is the sometime wind villain… the Subtropical Jet.

by Mike Godsey, mikeATiwindsurf.com

Sometimes you will notice a caveat in the forecast that a band of high clouds streaming from SW or WSW may come over us and spoil the wind but stopping the inland valleys from heating weakening the local pressure gradient.

Usually when I mention clouds I am talking about low-level clouds that are often extremely difficult to forecast so I will use weasel words like “Upper-teens winds IF the clouds do not block heating in the inland valleys” Since these clouds form locally or nearby they often develop and move over the valleys after the forecast is published.

Whereas, when I am talking about the higher clouds of the subtropical jetstream I am much more confident about their impact on the winds.   This is because these clouds are in a narrow band extending for hundreds of miles and their location later in the day is far easier to gauge.

This animation of the satellite imagery for Dec. 4, 2019, shows these clouds of the jet completely missing La Ventana and Los Barriles today. Hence the upper-teens or stronger winds.

Now, Thursday Dec. 5, those clouds are much closer to La Ventana making the mid to upper-teens forecast iffy since these clouds may kill the pressure gradient to the inland valleys.

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West Coast Wind Blog: We owe it all to a Cut-Off Low as Baja winds ramp up.

by Mike Godsey, mikeATiwindsurf.com

With a bit of luck and a Cut-Off Low that behaves according to the models we see a 3-5 day El Norte blow for La Ventana and Los Barriles, Baja Sur.

This graphic for Saturday Nov. 30, 2019, shows the setup.

1. First, notice the huge storm over the mid-USA. This low-pressure system, that brought crazy winds, rain and snow to much of the west coast a few days ago is now tracking eastward.

2. Now note the second large storm out in the Pacific just off the west coast of the USA. Normally this storm would bring a day or two of stormy weather to the west coast and then move into the Great Basin displacing the El Norte wind creating high pressure located there. But far above this surface storm at ≈ 18,000 ft. is a near Cut-Off Low that is mostly disconnected from the upper winds that steer weather systems from west to east. This means this surface storm is likely to just loiter off the west coast for a few days.

3. Check out the small high pressure area in the Great Basin. This high pressure should cause El Norte winds today that augment the La Ventana local sea breezes today.

4. Notice the isobars extending from that high pressure. The closer those isobars are to each other the stronger the pressure gradient making for stronger winds.

4. This is creating the El Norte winds indicated in green in the Sea of Cortez. If that Cut-Off Low above storm#1 holds station while storm #2 departs eastward then the high pressure#3 can stay over the Great Basin and we see days of El Norte winds.

 

 

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West Coast Wind Blog: Tropical depression upgraded to a named storm by National Hurricane Center.

by Mike Godsey, mikeATiwindsurf.com

The National Hurricane Center has upgraded the approaching low pressure storm to a Tropical Storm named Raynond.

 

 

Below is an animation of ECMWF model of the storm’s trajectory as well is a summary of all the latest model forecasts for trajectory and wind velocity.

 

 

Note that there is great variation since this is a part of the ocean with sparse data for the models to work with.

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West Coast Wind Blog: Nagging clouds try to limit Baja local sea breezes

by Mike Godsey, mike@iwindsurf.com

The last few days have seen barely a trace of El Norte winds over the Sea of Cortez. But El Sargento, La Ventana and to a lesser extent still can see mild local sea breezes if there is enough blue sky to heat the inland valleys.

Unfortunately, yesterday Nov. 13 saw heavy clouds over the area that stopped the sea breeze from developing.  Today the same clouds mass is streaming from the SW with the subtropical jetstream. However the cloud band is more to the south. And the models suggest most of the band will move away from the La Ventana area later today. This would allow the local sea breezes to ramp up.

This satellite imagery shows those clouds as dawn sweeps over Baja.

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West Coast Wind Blog: Excuses, Excuses… Now a Cut-Off Low + eddy make Bay Area & Southern California forecasting tricky.

by Mike Godsey,mikeATiwindsurf.com

For several weeks now our forecast team has been struggling with San Francisco Bay Area forecasting during a surface eddy pattern that is unprecedented in its duration and longevity. Now we have to add a Cut-Off Low up at ≈ 18,000 ft. to the mix. And there is a reason for the old rhyme “Cut-Off Low… weatherman’s woe” These beasts are hard to predict since they are cut off from the upper-level winds so they can wobble around randomly.

This animation below shows both the eddy at the surface and the Cut-Off Low at ≈ 18,000 ft:

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 as you can see in this video. Imagine trying to this:

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.

 

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West Coast Wind Blog: Ships at Sea and using the right tools.

by Mike Godsey, mike AT iwindsurf.com

Note: This blog uses Southern California as an example of picking the best model using ship reports but the basic idea of the blog is relevant to all regions in the USA.

On winter days as I walk through the La Ventana campground I am always impressed by the thoughtful kiters and windsurfers who print out and post the day’s forecast on clipboards right where folks stand to judge the winds. But I also feel a bit downcast when I see the models they pick to print. Most of the time they pick websites that use the old GFS model. The same is sometimes even true for the web sites for local resorts as you can see in this, all too true, warning about the model output from the Captian Kirks resort.

Don’t get me wrong. The GFS model is great for following large scale wind patterns and is one of your best choices if you are forecasting storms or if you are a mariner. The problem is that the GFS resolution is too low to properly factor in the topography that so strongly impacts the wind at most launch sites.

The trick in forecasting anywhere is to know which model, on any given day, is doing best at capturing the reality of the wind later that day. And that takes years of experience as well as knowing how to interpret satellite imagery, weather balloon reports and, and yes, even ship reports.

Let’s take a look at this Southern California day as depicted by the windy.com web site and how well the ECMWF 9 km model did forecasting an eddy compared to the NAM 3 km model.

The first part of the animation shows the ECMWF 9 km forecast for an eddy over the Southern California Bight. Notice how the forecast eddy spans almost the entire middle portion of the Bight. This large eddy is supported by the NNW winds you see in the upper left corner of the image. It is also supported by a thermal trough extending from a low pressure just north of the Sea of Cortez. Note how the modeled isobars of the thermal trough cover the entire Southern California Bight.

Such a large eddy could easily keep the afternoon beach winds very weak. So in forecasting, we have to determine the accuracy of this model output. Sometimes we can do this by looking at the swirl pattern of the marine layer clouds in the satellite imagery. But often that imagery is too fuzzy at 7AM. Another way is to look at wind reports from ships traversing the area.

As you examine the ship wind reports below notice that the furthermost south ship report does not jibe with the ECMWF modeled eddy.

Now, look at the NAM 3 km animation. Notice how the NAM has the isobars of the thermal trough more focused in the northern Southern California Bight. Now looking at the ship reports notice how their wind reports more closely follow the modeled eddy winds.

So, in this case, I would tend to forecast the eddy dying midday and wind peaking in the Long Beach area. Why, because I picked the right tools for the job which in this case was using the NAM output and ship reports.

 

 

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