West Coast Wind Blog: Why so many Bay Area eddies this season. Part One

Part one of this blog below is about the smaller eddies mostly in the Bodega to Golden Gate area that have been so common during the 2019 summer season. These eddies often totally or partially die in the afternoon making for extremely difficult forecasts since the southerly eddy wind may die allowing NW wind to curve into Bay.

Part two of the blog, coming soon, covers the huge elongated eddies that have also been common this season. These eddies may span the waters from Pt. Arena to past Big Sur and usually endure all day and throw southerly wind at the Bay Area all day. These huge eddies are easy to forecast.

At this point, if you are a coast or 3rd. Ave. kiter or windsurfer, you are fed up with all these eddies and all the forecast talk about eddy. In feedback, customers have even accused us of just pasting in a boilerplate text about eddies rather than doing original forecasts. And I can understand that thought since time and time again almost exactly the same eddy producing conditions have developed and it is hard to come up with new phrases to describe essentially the same pattern.

Does this text sound familiar: “The North Pacific High pushes a lobe of high pressure into far Northern California so our ocean wind west of the Farallon Islands turns from NW to NNW. At the same time, low pressure bulges over the coast west of Chico. So we have an eddy in the Bodega to Daly City zone. Meanwhile aloft strong NNW winds aloft create wind shear enhancing the eddy. In the afternoon the eddy probably fades but still enhances north tower to Point Blunt to Pt. Isabel winds while residual SW flow in the Hwy. 92 gap make the winds unreliable at the 3rd. Ave launch site.” If you are a 3rd. Ave kiter those words bring dread while Pt. Isabel windsurfers rejoice.

So where are all these eddy conditions come from and where are our normal NW winds from the North Pacific High?

Short answer: Unusually warm north Pacific encourages North Pacific High to expand northward and southward while El Nino southerly storm track causes NPH to kink inland over far Northern California so our ocean winds turn from NW to NNW while low pressure moves over the north coast and the combo results in eddies.

Longer but still very simplified answer:

1. El Nino has brought warmer waters to the north Pacific and this encouraged the North Pacific High to move much further northward than normal.

2. This year we are in an exceptionally warm phase of the PDO or Pacific Decadal Oscillation this also encouraged the North Pacific High to move way northward.

3. Arctic warming has continued and Alaska lost all of its sea ice in August. This also encouraged an expansion of the North Pacific High and at times it reached into the Bering Sea and even over Alaska and well into the Arctic. Normally the bulk of the North Pacific High is west of the Gorge by mid-summer.

4. The combo of 1+2+3 above means we often had an NPH wind a weird elongated shape stretching from Alaska into Baja waters.

5. This winter saw an El Nino pattern with the storms taking an unusually southerly track hence the heavy snowfall and even rain in La Ventana, Baja.

6. Then as we moved into summer the storms became less frequent and smaller but they still tracked more southerly than usual bringing unstable convective air over the Pacific Northwest making for less reliable and more up and down Gorge winds.  This is happening even though in the tropics the El Nino is fading to neutral. In the second
image, you can see 2 low-pressure systems and their southerly track and the fragmented nature of the North Pacific High and its  N. and S. expansion.

7. As the storms tracked across the Pacific from West to East they often encountered the greatly distorted N. to S. North Pacific High. Often the North Pacific High was even split into 2 or 3 parts by these storms leaving Northern California with a North Pacific High that was off our coast rather than the Gorge coast.

Compare the second image of the fragmented North Pacific High this July with the third image showing the average shape of  the North Pacific High in July over the period from 1967 to 2010.

So let’s look at how we make the shift from a strong NW pattern like we saw Wednesday, August 21 to the beginning of an eddy pattern today Thursday, August 22. Then in Part 2, we will see how Thursday’s tiny, quickly destroyed eddy turns into a massive elongated eddy Friday, August 23.

NOTE: There are 10 seconds between frames in this animation.

In the first frame, showing Tuesday to late Wednesday, notice how in the first image the North Pacific High’s isobars (in white) are roughly parallel to the coast so strong NW surface winds are along the Bay Area coast.

Then in the next image, for Thursday, the isobars of the North Pacific High begin to move inland into far Northern California while at the same time low pressure bulges over the coast north of the Bay Area. This causes a tiny eddy to develop in the Stinson Beach area just north of the Golden Gate.

This tiny eddy is destroyed later Thursday morning by the strong NW ocean wind.

The next image, for Thursday, shows the very strong winds up at ≈ 18,000 ft. that cause the North Pacific High’s isobars to kink inland over far Northern California setting the stage for an eddy.

The final image shows the very strong winds at NNW to NNE winds at 2000 feet that reinforce the eddy b and end up forming a counter-clockwise spinning mass that causes the eddy to endure all day and to exp

How about the future and eddies?

This El Nino is already fading so that causal factor is gone for a while. Likewise, the PDO should move to a cool phase in a few years. But Artic warming is going to be with us for a long time. So we are unlikely to see as many eddies next year the future is going to see more eddies than we did even 5 years ago. So eddies are going to be a factor in the future.




West Coast Wind Blog: Wishy-Washy forecast as Pismo and Santa Barbara westerly winds battle with northerly inland winds.

by Mike Godsey, mikeATiwindsurf.com

Check out this wishy-washy forecast today. Basically, I am said that the winds might be strong or might be weak.

Why couldn’t I pin it down more precisely for Pismo and Isla Vista to Ledbetter?

Basically, because there was a going to be a battle waged over both sites as NNE to NE winds from the interior tried to divert the ocean westerly winds that was following a strong pressure gradient.

This graphic and the accompanying Pismo and Ledbetter wind graphs tell the story.

And note that I was right the winds were strong and they were weak at both Pismo and Ledbetter. As I get better forecasting I will be able to pinpoint these fades better.

But for right now being wishy-washy is the right course.




West Coast Wind Blog: Why are eddy forecasts so hard

by Mike Godsey, mike@iwindsurf.com

Backcast:  Pt. Isabel low to mid 20’s was clearly stronger than the mid to upper-teens I forecast! Why can’t we forecast such strong eddy winds reliably? Just take a look at this hourly animation of the eddy today August 18, 2019.

Notice how much it changes from hour to hour and remember that in reality, it is changing almost minute to minute.

To put it mildly it is like forecasting the exact track of a tornado. Simply not possible.

West Coast Wind Blog: Elongated eddy from San Diego to past San Francisco

West Coast Wind Blog: Anatomy of a forecast wipeout for Santa Barbara to Ventura.

by Mike Godsey, mike@iwindsurf.com

Yesterday, Wed. August 14,  2019 I really blew the Isla Vista to Ledbetter forecast and Ventura went over the mid-teens forecast. True, I did warn of “much stronger winds than forecast if the Gaviota eddy died” But still… it was a crappy forecast. This an animated blog about what happened that day to blow

Sometimes I blow a forecast for very complex reasons that I can understand in retrospect. Othertimes I am oblivious to what went wrong. But sometimes like yesterday the reasons are very clear but still impossible to forecast in advance.

The uncommon Gaviota eddy had spun up and at even 11:30 AM looked like it would really block the robust westerly winds from reaching the Isla Vista to Ledbetter to Ventura zone. This animation shows that I was wrong. And eddies, by their very nature, are very unpredictable beasts.


West Coast Wind Blog: Eddy what eddy? Trying to forecast the invisible.

by Mike Godsey, mike@iwindsurf.com

As you all know the location, thickness and movement of the marine layer clouds are critical in making the winds at every
site in the San Francisco Bay Area. The same is true in forecasting. The difference is that we have to try to forecast where the clouds will be many hours in advance so people who have jobs can plan their day in advance.

And these days a counter-clockwise spinning eddy makes forecasting the clouds and winds far more difficult than in past years. But still, we can usually use a combo of model output, sensor data and satellite imagery to localize the eddy. But for an accurate forecast of the afternoon winds we need to be able to actually see the size, location of the eddy to determine whether it is going to die or endure. Since if it endures sites like Pt. Isabel will rock while the 3rd. launch becomes unreliable or worse.

If you have lived in the Bay Area for decades you will remember that heatwaves used to occur mostly in Sept. and Oct. As you have noticed from the forecast discussions and the TV news it is upper trough and ridges that bring cooling and warming respectively.

But a changing climate has these upper troughs and ridges up at ≈ 18,000 ft. making greater excursions towards the north pole and towards the equator. This means we sometimes have colder winters and sometimes hotter summers with the latter being more common.

So how does this make forecasting eddies more difficult? Upper ridges are areas of descending air that compresses near the surface producing heating. This same subsidence lowers the inversion and compacts the marine layer clouds into fog and may even cause the marine layer clouds to evaporate as we are seeing today Aug. 15, 2019.

Check out this first image above from the Bodega profiler today. Notice the very hot air, in red, above the very thin cool air, in blue, which has had its moisture evaporated hence not visible clouds.

This means the swirl in the marine layer clouds created by the eddy does exist so the eddy is invisible.

This issue began to appear Tuesday Aug. 13 for Kerry. At dawn there was only a trace of clouds making it difficult to see the eddy. And today I am forecasting an eddy that visually is invisible

Look at the first frame of this animation and notice how you can not tell there is an eddy. Only after the 7:30 AM forecast can you clearly see and eddy. This situation with invisible eddies will be an increasing problem in the future. And already forecasting how eddies impact specific sites, especially 3rd. Ave. inside is a nightmare.



West Coast Wind Blog: Pismo Beach wind and fog, the last mile.

by Mike Godsey, mike@iwindsurf.com

Forecasting for Pismo winds in the summer is very tricky and we are slowly learning the complexities of this area. Here are some of our baby steps up the Pismo forecasting learning curve.

The marine layer clouds are often way inland in the morning in the Pismo area. But despite the clouds forecasters can see the potential for a strong NW to SE pressure gradient in the afternoon favoring Pismo winds.

Typically the clouds burn back to easily to about a mile inland of the coast. But to get strong wind we need clearing beyond the coast. And that is often very hard to forecast.

The following images show these issues.

In the first image forecasting, Pismo winds look easy.

You can see the ocean winds in the AM are mild along the beaches and Lopez has stronger winds due to the local venturi.

Then in the afternoon as the inland valleys heat up and wind accelerates near Gaviota the pressure gradient goes up and the wind is sucked over Pismo. Now for some reality.

Unfortunately, the marine layer clouds are also an issue. Each time an upper trough at ≈ 18,000 ft. passes near Southern California the marine layer deepens and slides over the coast in the AM.

Then as the land heats the clouds burn back but the pressure gradient towards Lopez encourages the fog to stay over Pismo keeping the winds light unless the clouds burn back over the coast.

This second image shows how critical the marine layer location is for Pismo.

The models do a great job forecasting how deep the marine layer will be each day and give some hint of its retreat. But they can not forecast marine layer burn off with enough accuracy for us to accurately forecast that last mile of clouds on the Pismo coastline.

But what we can do is forecast the presence of good Arroyo Grande to Cachuma Lake pressure gradient and give you a feeling for the chances of clearing. From that, you can use your window or cams to see if the last mile clears.





West Coast Wind Blog: Eddy, 950mb. winds and Bodega

by Mike Godsey, mike@iwindsurf.com

On this day the WF-WRF barely showed a hint of an eddy. The NAM surface had a better hint. But, as I have noticed again and again for larger elongated eddies, the 950 & 975 NAM do a very good job forecasting existence
of an eddy and its duration.

Also notice how a subtle shift in the eddy location can radically change the wind direction at Bodega. Also notice how such movement made the fog in the Hwy. 92 gap suddenly disappear due to SE winds. Normally such clearing foretells good NW wind at 3rd.

West Coast Wind Blog: Gorge and Bay Area wind and weather go bonkers!

Gorge version

by Matt Souders & Mike Godsey

You may have noticed that the wind and weather has gone a bit bonkers at times this year for much of the west coast. You’re not wrong – the data backs up your impression. And, no, it is not Global Weirding, at least not directly.

This year the Gorge had a very mild winter that had daffodil bulbs budding in late February and then had snow on the ground for almost a month in March. Then it had a crazy long May heatwave. Then unending mid 30’s wind in June. And then a long period of weird clouds and sporadic wind in July.

All this while, in the San Francisco Bay Area, there’ve been long periods of eddies and southerly winds along the Bay Area coast with the beloved NW winds of the North Pacific High AWOL.

So what is behind all this Gorge and San Francisco weirdness? Basically, the direct cause is the atypical shape, size and location of the North Pacific High. And that, in turn, was impacted by:

  1. El-Nino induced north Pacific ocean warming encouraging the northward growth of the North Pacific High
  2. El-Nino causing the average storm track to drop southward so storms more frequently distorted the shape of the NPH, often breaking its northern and eastern flanks off and pushing them into the interior Northwest helping eastern Gorge winds.
  3. A strong warm phase to the Pacific Decadal Oscillation (PDO) which helped warm the Alaskan coastal waters and, from there, the entire Pacific coast cold water current.
  4. One of the warmest seasons on record in the Arctic Ocean (common during warm PDO/El Nino, but made worse by the recent Arctic warming).
  5. The presence of higher pressure over the Pacific Northwest and the warmer coastal shelf waters from the Alaskan current are thinning the marine layer and this, in turn, is causing winds in the Corridor to be more unstable, to blow solidly for shorter intervals many days.
  6. The El Nino is also creating an opening for unusually sharp upper-level troughs to pass through the Gorge region which keeps temperatures sometimes cooler than normal during early summer and changes the nature of marine layer clouds in the Corridor, giving them more height and picking them up off the river which makes the wind more up and down. This also has meant stronger winds aloft which helps sites out east. On the downside, though, with more upper-level NW winds behind troughs, traditionally good launch sites out east like Maryhill and The Wall on the WA side are seeing wind shadows mixed with WNW blasts as the wind in the area is more WNW rather than the more WSW in past years. Meanwhile the change sometimes benefits the Oregon side Rufus launch

Let’s look at the North Pacific High this year versus the past decades.

First, in this image let’s look at the average shape and location of the North Pacific High over the period from 1967 to 2010. (I picked that period because the North Pacific High was very predictable back then while in more recent years it has a become way more variable for reasons we will get to later.)

Notice how the North Pacific High is a small oval and way to the south during the winter.

Then, starting in March, the oval NPH expands and is
centered west of Baja. This is why the winds at the Punta San Carlos wave sailing mecca begin to build in March.

Then, as Spring turns to Summer, the NPH’s average location moves northward. In May, for example, it’s typically centered west of Southern California, which turns winds NW along the Central and Southern coasts.

Then the NPH centers off of the San Francisco Bay Area and the NW winds peak after each passing storm. In July, it centers west of the Gorge where it works with the low pressure in the Columbia Basin to make the Gorge winds blow very reliably, especially in the Corridor.

Finally, in September, it shrinks and begins moving southward and west coast westerly winds fade.

Remember these are average locations and each time an upper trough/surface low pressure passes to the north the NPH moves southward.

Now looking at the second image compare the July Average North Pacific High and compare it to today Thursday, Aug. 1, 2019. Wow, quite a variation from the norm!

Clearly, the North Pacific High is much larger and fragmented by all the low-pressure systems following a southerly storm track. Especially note how the NPH has been bumped away from the Gorge.

Every few years, the El Nino-Southern Oscillation – a warming of tropical Pacific sea-surface temperatures linked to a slowing or even reversal of the normally easterly trade winds – begins.

El Nino is tied to a host of changes to the normal climate of the west coast. If you live in California you know that a strong El Nino brought more rain than normal to California this winter.

However, El Nino’s effects in the summer are not as well understood, but, this year, we are seeing some strange ones.

El Nino increases westerly winds south of the North Pacific High. Those west winds have often been stretching the North Pacific High north and south.

That is why the forecast has sometimes noted that the NPH stretched up to the Gulf of Alaska or even over Alaska itself.

Those El Nino westerly winds have sometimes crippled the southern flank of the North Pacific High, disrupting Hawaii’s trade winds.

This last graphic shows what the North Pacific looked like in late July. This image shows all the major players in the weird wind pattern we have often seen this spring and summer.

So what does the future hold for the Gorge windwise?  The El-Nino will subside soon and the PDO will gradually move towards a cooling phase. However all evidence suggests that El-Ninos are getting stronger in recent decades. Plus the overall warming of the Arctic is going to be an issue. Even in a cool PDO, a warm arctic may mean we struggle to get the deep marine layer influences we once did, as coastal waters may be just warm enough to make it difficult to keep those marine air masses stable.

West Coast Wind Blog: Forecasting UP AND DOWN Gorge winds.

A Slack discussion: Learning to recognize a pattern for very up and down winds in the Columbia River Gorge

by Matt Sounders & Mike Godsey

windfind 4:36 PM

Here is a animation I am working on to help explain the UP AND DOWN winds today.  Even over the ocean at dawn you can see the instablity.

look at all of those vertical strat-cus west of the Cascades

there must be a lot of mid-level cool air

Notice reform clouds on eastern mountains

Luv how the marine layer clouds and wave clouds get wiped out.

they erode and are replaced by that garbage strat-cu

I really like how these animations allow you to review things over and over in motion.

very clearly replacing the cool stable layer with a cool unstable mid-level layer

yeah…these rocking animations are highly useful

Shud try to grab and compare Troutdale 7AM and 7 PM profiler and skew t

that could actually be pretty amusing

now you see the thin inversion…now you don’t!
alas, the models were way overestimating the thickness of the marine inversion on Monday/Tuesday for today so I expected today to be better for longer

very…very-weak top-of-boundary-layer inversion in the morning, then immediately wiped out by steep lapse rates in the midday period

Actually looking at the satellite more closely there was not much of marine layer over Troutdale

it looks very muted even on that profiler chart

what about Portland?
or Astoria

So even at dawn unstable air had moved to Troutdale.

so it would appear. :confused:

You can see it arriving at Astoria

no inversion at all

quite cold at the top of the boundary layer

This would make a good tutorial for Gorge mets. I will grab this conversation and imagery and put into a blog. Then you can add texts. Not all blogs have to be aimed at customers.  We can publish it just for internal use.

modeling as of late Monday had a little bit of an upper ridge over the NW US…instead it’s a little bit of an upper-trough

that makes a large difference

We have to get better at forecasting winds beyond the typical up and down.

new messages

the users are getting a bit savvier and have higher expectations these days