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
the.forecast.

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

West Coast Wind Blog: Inside Golden Gate wind rages while calm just outside.


by Mike Godsey, iwindsurf.com/ikitesurf.com, mikeATwindsurf.com

I took the helicopter photo in my banner above on a day when it was nearly calm at Pt. Diablo just outside the Golden Gate’s north tower. But the strong NW aloft were buffeting the copter and there were strong surface winds inside the Golden Gate off Crissy. This morning a customer mailed me about yesterday’s winds which sound like a similar day.

“Everyone was asking me today why outside the GG bridge was nearly zero, just inside the bridge was solid 25 gusting higher, Anita was gusting to 30. When I went down to Blunt it was much lighter than I was expecting and much lighter than it has been for the past week. I can’t explain it … Would make for some interesting forecast comments and maybe even a blog post. MS”

Here is my response (slightly elaborated for clarity):

Hi MS,

I have not forecast since last Friday so I am a bit out of the loop. However, I have seen the pattern you are describing so I can take a somewhat educated guess.

The Marin ridges NW of the Central Bay are one of my favorite for meteorology hikes since I can both see the Central Bay water, feel the nature of the wind above the Bay and, politically incorrectly,  sometimes release Helium filled toy balloons. From the high ridges above the Marin Headland, I could watch the balloons erratic vertical flight pattern as it headed above the Golden Gate.  (in recent years I have done the same in the Hwy. 92 gap trying to understand the SW eddy flow that impacts 3rd…. not much luck there…yet)

The hikes and balloon play suggested the following hypothesis.

This first image shows the 449 Mhz. Bodega profiler from yesterday. Note how Bodega, which is upwind of the Golden Gate,  had very strong WNW to NW wind just aloft from 200 meters to over 1000 meters.

At this elevation these winds would crash into the Marin coast range and which creates a lot of NW to WNW moving turbulent wind that would end up several hundred feet above the Marin Headland and Sausalito hills inbound to the north tower Golden Gate to Point Blunt area.  

Now, look at the insert above which shows the Mt. Tam winds yesterday at about 2572 feet.  Since Mt. Tam is way taller than nearby hills you would expect steady winds unless there was turbulence. But the data clearly shows there you can see the Mt. Tam wind is extremely gusty.

Meanwhile, at sea level, you have NW surface wind that is curving in through the Golden Gate as WSW wind at Crissy and to Treasure Island. This is a cool dense wind and as such, it tends to hug the surface of the water. And just above that WSW wind you have turbulent warm air moving from the WNW-NW. What I have observed that when this happens the WSW wind mass is pushed slightly southward leaving a much lighter wind area outside the Golden Gate, near the north tower and near Point Blunt.

A similar pattern happens frequently to Pt. Isabel with strong NW winds aloft and at the surface as you can see in this blog and the following animation.

https://blog.weatherflow.com/why-did-i-forecast-strong-winds-everywhere-except-pt-isabel-and-berkeley/

Looking at the animation notice how the WSW wind inbound from the Golden Gate is diverted away from Pt. Isabel and since Brook’s Island blocks any NW wind people are slogging outside.

So, looking at the animation, mentally just shift that diverting flow over the Central Bay to over the Marin Headland and you can see how that might weaken the Point Blunt,  north tower and winds outside the Golden Gate.

Incidentally, my experience is that the WRF greatly overestimates the impact of this pattern on Treasure Island and somewhat overestimates it for Point Blunt. Tell me what happens today.

This pattern is rarely as pronounced as you describe. But when I think I see this pattern I mention in my forecast something like: “Strong winds inside at Crissy and Treasure Island but fading towards the north tower and Point Blunt”

Let me know if the above makes sense. I will probably do a blog suggesting this as a possible explanation for what people observed. (And here is the promised blog)
Mike

 

West Coast Wind Blog: Blame it on the Kid. Part 2, the aftermath.

by Mike Godsey, mikeATiwindsurf.com

In Part 1 of this blog, Blame in on the kid I wrote about how unusual this season has been due in part to an El Nino pattern.

 

And for the west coast, El Nino means an unusually southerly storm track.

 

That blog left off talking about an 1000 mile wide winter type storm and cold front that was poised to stall off the coast of the Pacific Northwest.

Part 2 covers what this low pressure has done to our winds the last few days focusing on today July 11, 2019.

This first image shows that the low pressure is now centered NW of the Gorge and due west of the Canadian border.

 

You can also see the isobars of a ridge from the North Pacific High over the Gorge. As you know this means westerly winds for the corridor.

 

 

However, there are a  few more players poised to spoil those west winds.

 

This next image shows the modeled rainfall for today as depicted by the ECMWF.

 

And radar imagery confirms that we had spotty rain in the Pacific Northwest much of the day.

Combine all of this together and you have a pattern of

  1. unstable air
  2. a disrupted marine layer
  3. winds that easily lift from the surface

 

This is a recipe for UP AND DOWN winds.

The animation below is a composite of satellite imagery, sky photos, profiler imagery and winds graphs focusing on 3 PM today at the Hatchery.

 

 

 

West Coast Wind Blog: Blame in on the kid: Gorge winds weaken: Part One

 

by Mike Godsey, mikeATiwindsurf.com

Here is part 2 of this blog.

Did you notice how much weaker the Gorge winds were yesterday July 8, 2019?

And you have also probably noticed that this season has mostly had cooler air and water temperatures for this time of year.

And there have been more winds out east than typical for late June and early July.

And it is hard not to notice the atypical clouds most days. And now… look at the forecast for mild wind and showers from Portland to the coast.

Then there is the little matter of a 1000 mile wide winter type storm and cold front that will hit the coast today.

In the simplest terms, we are still in an El Nino pattern. And for the west coast, that means an unusually southerly storm track. Hence all the atypical variables above.

More specifically it means that the upper troughs at 500 MB. that steer storms, deepen the marine layer and increase onshore flow are still coming over the Pacific Northwest in July just like it was May or early June

This is obviously this is a topic for a major blog, which we are working on, but today I only have time to highlight the current storm.

So look at this animation that shows the storm and the associated upper trough (the southward extending loop of upper-level winds) as they appeared yesterday.

Note that lobe of the North Pacific High off our coast. This helped create our mild pressure gradient yesterday and today that lobe has retreated into California waters

So our pressure gradient is weaker today and if you check the radar later today you will see showers east of Portland.

Now note the upper ridge which is the northward extending loop in the upper-level winds over the Pacific
Northwest. That upper ridge is probably going to block the eastward movement of the storm. So it will linger along the coast and slowly drift northward into Canadian waters where it dies. Except for that upper ridge, we would be seeing
more lot more rain.

 

West Coast Wind Blog: Using sensors in the Wall to Rufus corridor

by Mike Godsey, mikeATiwindsurf.com

We have added a Public Domain sensor located on the John Day River Bridge east of Rufus. It will read LOW compared to the actual wind at Rufus but by looking at the wind at The Wall sensor and this sensor you will have a good idea of how windy it is at Rufus.

It also gives you another way to interpreting the often incorrect readings at the Maryhill and The Wall sensors. If there is a hint of WNW on the new John Day sensor the Maryhill and The Wall sensors will show strong winds that are mostly on the OR side of the river.

This blog link has lots of imagery and details about the wind and sensor issues at The Wall

If the John Day sensor shows hints of WSW winds the Wall will rock and the sensors will be accurate.

Below is a graphic that shows what is happening.

And here is a link to the John Day River Bridge sensor:

https://wx.iwindsurf.com/map#45.695,-120.78,12,1

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