wind prediction request for FM Godsey

[jroberts]

Mike, you asked recently, so here goes.

A more useful (actionable?) forecast will have a probability of what you predict happening. Then, once you demonstrate predictive or model skill, one can determine if the probabilities are appropriately assigned. You have the benefit of keeping score thus improving your forecast ability. It may turn out that forecasts are off when certain meteorological conditions occur. This will permit you to tighten the probabilities in situations that are normally well-behaved. This is what wind industry forecasting companies do, although they hedge, too. This is because you don't want to enter into a PPA with little confidence you can deliver the contract.

An example:

There is a 50% probability wind at marker 14 will exceed 9 m/s between 2 and 4 pm. It either gets there or it doesn't, but it should 50% of the time. If not, you need to reassess. It is fine to have large uncertainties when conditions warrant, but giving a tighter probability will help us all. There are a number of ways to set up this system--and one size won't fit all, but's give it a try. I suspect that you already have some of this info. I can help set up the propagation of uncertainties and validation if that is useful to you.

Hope this is clear.

Jeff

[MalibuGuru]

I know there is a super computer that could model a probability of a site reaching a certain wind within the hour by monitoring coincidental data points. iwindsurf has those data points.

For instance, my local spot works on thermals and prevailing ocean winds. If it is super windy at Pt. Conception, this creates an eddy, and my spot shuts down. Conversely if it is a rapid warm up, combined with minimal offshore flow, we get real windy.

I've often wondered why the geniuses at weatherflow wouldn't take their millions of pieces of data, and model them hour by hour. Once you figured out each site, the cash registers would be ringing.

[windfind]

Hi Jeff,

If you are a long term customer you may recall that there was a period where I put confidence assessments expressed as a percentage in the boxes below each sites table. e.g. Probability or correct forecast = 70%

I dropped it after a couple of months because:

1. Exactly zero % of customers commented on it or said they found it useful.

2. To most people the quality of the wind is as important as the velocity reaching the forecast value. e.g. did it fill in to shore. was it too up and down, did it build too late or die to early, is it from a useful direction.

3. For most sites the wind varies greatly different parts of the sailing area. e.g. there are lots of days at Crissy when a skilled sailor can use knowledge of countercurrents and where the wind line will be to slog in low teens winds 2/3 of the way to Yellow Bluff then short tack up to the north tower and have an epic day there in low 20's wind. So they would say a low 20's forecast was perfect. While a newer sailor who sat on the beach or struggled to get much past Anita Rock would say the forecast was useless.

4. For most bay sites the wind is much stronger outside than inside. And unless many people sent in reports we could only verify the accuracy of the forecast by the sensor numbers. So most of the forecasts would look like fails to us.

5. The company did not support the idea at all because of the above plus increased forecast time and the inability to monetize the product.

With my background as a former scientist/college professor I loved the idea.

Actually an idea that I hope to get implemented one day is to rather than having the sensors give the average wind and the peak gust and deepest lull to have them give the standard deviation of the wind velocity around the average. Even customers who did not have a clue what a SD is would quickly figure out the closer the 2 lines were to the average the higher the wind quality. Weirdly most customers actual think the current gust and lull lines show this.

Still, I would be interested in knowing what you propose since we have corporate and government customers who might like such confidence levels.

So mail me at mike@iwindsurf.com

Mike Godsey
iwindsurf.com

[airwave]

Todays evening daily briefing for tomorrow is not showing up.
Someone forgot or somethings wrong.

I should add...MAC with Chrome...in case its a tech problem.

[spennie]

In the "Introduction to Meteorology" class I took, the instructor talked about Chaos Theory, originally presented by a meteorologist, which states that there are too many variables, interacting with each other, to ever let a specific pattern remain for any length of time. It's also known as the Butterfly Effect, where one little change sets off a series of changes that are impossible to predict. So by the time a supercomputer predicts what the wind is going to do, it will have already changed. We learned that forecasts are usually pretty good for the next day, sketchy by day 3, and useless after 5 days, no matter how good you are.

Think about life before iWindsurf, and thank the Heavens it's here! Imagine just driving around to see if it's windy somewhere, especially if you live in the Gorge, or Bay Area! Yikes!

[starfish]

Guys put your gear in your car and go if its windy. If its not windy then don't go simple. You don't need no stinking forecasts. Oh wait that only works if you live in hood river or white salmon. Have a nice day. Its blowing 4.2 at the hatchery right now.

[Arrgh]

[fxop]

Mike -- question: What does it mean when you say a site will reach "weak low 20's"?

Does that mean the wind will be in the low 20's but more susceptible to fading? Closer to 20 than 23?

Just wondering,
fxop

[isobars]

This is starting to remind me of the time when we got our forecasts by phoning or walking into the Albuquerque NOAA "weather bureau" forecasting center at the airport to talk to their wind expert, Roy Pennington. He loved helping us, but had to laugh when people would ask which of two lakes a few miles apart would get better wind tomorrow or next weekend. His answer, translated into today's jargon, would be, "DUDE; even our best forecasts are for groups of counties for the next few hours. We're in the Rocky Mountains, to boot. Get real."

In case that doesn't get the picture across, consider these scenarios I've witnessed many times:
• The Hatchery is blowing a solid, sustained 4.2 while the Even Site is a very holey 6.5, if that. (they're basically a very broad reach apart). Ditto Doug's vs Rowena, Roosevelt vs Arlington, etc.

• We're sitting beside a big NM lake 3-4 miles from the airport on relatively flat desert terrain. The airport's reported wind speeds, puffy clouds and flying birds we can almost touch, and the wind noise have all indicated wind averaging at least 30 from the west for hours now. On the water, for hours on end, it's blowing 5 from the east. We were certain that a bottle rocket fired straight up would turn SHARPLY west at 50 or 100 feet, and NOAA research explained why: wind won't stick to water colder by 20 degrees F unless and until that layer of cold air is blasted from the water's surface.

• One day, on beam reaches on 5.0s, we keep getting slammed from directly behind or ahead by sustained gusts near 40 ... at two lakes tens of miles apart in flat desert terrain. Conflicting wind strata overhead were struggling for dominance.

• A bunch of good Gorge sailors are having a GREAT time B&J sailing on sinkers together on the river, each rigged perfectly for the day's steady winds. Looking more closely, one sees sail sizes from 4.2 to 6.2, with a weight range of 90 pounds being a random factor in sail choice.

• One day, a blast of unforecast dead offshore wind lasted from suppertime until the following noon without ever dropping below 80 mph. Damages and rescue costs ran into six figures just for boats and boaters. When we asked the weather bureau what caused it, they just shrugged and said, "We never saw it coming either, but our best guess is ...". That happens often there (in Utah's Wasatch Front), but it's often forecast and clearly explained. Not that day.

With the topographic and meteorological complexities of the Bay and Gorge, we want pinpoint forecasts, with useful odds? Too many butterflies, and it's often difficult to tell in advance which one will be that day's -- heck, any given reach's -- 500 pounder.

[andydavis]