Predict Wind - Which Models do you use?

[ColourfulOwl]

I think we can all agree, that Predict Wind has become an absolute staple for cruisers.

I'm based in the UK and am interested in hearing from you all which forecast models you use the most. Which have you found to be the most accurate/reliable?

[SailingHarmonie]

The only "right" answer is you use all the tools in your toolbox. No model is always better than all the others. Frequently the most important data to come from a weather run is the way the models agree, or do not. It is not a simple "majority rule."

I know it would be nice to say that ModelX is always right and you don't have to think about it past that, but that is not the way it works--until they develop the perfect weather model.

[s/v Jedi]

Originally Posted by ColourfulOwl

I think we can all agree, that Predict Wind has become an absolute staple for cruisers.

I'm based in the UK and am interested in hearing from you all which forecast models you use the most. Which have you found to be the most accurate/reliable?

In the Caribbean, Bahamas, Florida the best model changes every year. Mostly centered around the hurricane season, the model that shows best accuracy with the first couple storms is normally the best for the season.

The Euro model was very good butI have now seen the GFS model being more accurate. My default is still the Euro model.

Btw, these models are the same in other apps, like Windy.

[ColourfulOwl]

Originally Posted by SailingHarmonie

The only "right" answer is you use all the tools in your toolbox. No model is always better than all the others. Frequently the most important data to come from a weather run is the way the models agree, or do not. It is not a simple "majority rule."

I know it would be nice to say that ModelX is always right and you don't have to think about it past that, but that is not the way it works--until they develop the perfect weather model.

100% agree. But lets face it we all have our preferred tools and software's that we rely on a little more then others. Just curious to see which way people tend to lean towards

[Sailer_Med]

For the Spanish Med, particularly Costa Brava my short outlook tool is AROME the french agency model. Along side that I use SPIRE for longer looks.

[SailingHarmonie]

Originally Posted by ColourfulOwl

100% agree. But lets face it we all have our preferred tools and software's that we rely on a little more then others. Just curious to see which way people tend to lean towards

You might be missing my point... when the models all agree on a forecast trend, then I have confidence they are all likely to be close to correct, and picking a "favorite" doesn't matter.

If they differ in ways that are important to me, then I know that something between one of them and all of them are wrong. I have no basis for selecting which of them is more better other than a wild guess, or a "feeling" or maybe I could just pick the result I like the best.

If you still feel a need to pick one to believe over the others PredictWind has a Validation tool where you can compare the various models' past performance at a specific location. The data can be interesting, but does take a good bit of care to draw valid conclusions from. When I have looked at them in detail, I have never found a clear and consistent winner.

[wholybee]

Learn how to use the validate tool under forecasts, available on the web version, not the offshore app. For any area you chose, it will use historical observations to rate the models which is historically most accurate, and how.

Some models will be more accurate with wind direction, but not wind speed.
Some models will be more accurate overall, day to day, but won't as accurately model extreme events.
Some models are very accurate "overall" but don't account for land effects. Other models are less accurate, but do account for land effects.
The PWE and PWG are crap. However, they account for land effects well, in particular the high resolution PWE is good to use with the ECMWF to see what happens close to shore.
etc. etc.

Predictwind briefly describes the models here:
https://www.predictwind.com/why-predictwind-forecast/

Approaching from the standpoint of "which model is best" is how sailors get into trouble, and or conclude that predictwind/gribs are too often wrong and not valuable. You need to look at all the models, and all the strengths and weaknesses.

Also, you need to understand that it averages. The high resolution models are 9 square kilometers, and every hour. But the models you will likely use are 81 square kilometers and updated every 12 hours. Over 81 square kilometers and 12 hours, the wind will vary A LOT!

Also, NEVER, blindly follow a route that it gives you. If the predicted wind direction is off by only 3-5 degrees, that might cause it to predict you to be on the wrong tack, and put you in a completely different location.

From the standpoint of a cruising sailor (not racing) what you really need to know is that it is safe. And if there is agreement from all the models that it is, safe bet it is. So, look for agreement in the models when judging a departure time. In the few areas that wouldn't be true, local knowledge is needed.

From a routing standpoint for a cruiser, I found it is usually best to just go in a straight line, or as close to that as you can. In the little bit of offshore racing I did, I found that adding hundreds of miles for the "fastest" route would save less than an hour over 2 weeks. The difficulty being that the software mostly just wants to give you the "fastest" route, not compare it to a straight line. This changes if you a racing and/or have a fast sled.

I think many people expect technology to be some magic thing that gives them the best route, best weather knowledge, and gets them to the destination much faster. It isn't. Use it to know when it is safe/comfortable to go, then once you leave sail to the conditions you see.

One last thing. It took a few years for me to really appreciate the text reports that predictwind generates. Now, they are the most valuable thing they do. Generate a route and look at the text reports. Scan the wave height, wave direction, apparent wind angles, and apparent wind speeds. Do you want to sail in that? Yes? Great, go. Look rough and uncomfortable? Wait. No reason to even download the grib and look at it except to see what is in the area that might change things.

[hlev00]

My experience after using PW for two winter cruises along the US East Coast and to the Bahamas has been quite mixed. The first was winter of 2019. The other the winter of 2022. I generally find the Euro model to be more accurate more frequently, especially out more than two - three days. I haven't gotten a lot of value out of the PW enhanced but I don't discount them entirely. I look at which model most closely matches what I am experiencing at the time and look towards that as what I will use that day for my planning. If there are large divergents between the models I look at to what the average looks like or consider what the worst case would do to my planning.

[GreenWave]

Originally Posted by hlev00

My experience after using PW for two winter cruises along the US East Coast and to the Bahamas has been quite mixed. The first was winter of 2019. The other the winter of 2022. I generally find the Euro model to be more accurate more frequently, especially out more than two - three days. I haven't gotten a lot of value out of the PW enhanced but I don't discount them entirely. I look at which model most closely matches what I am experiencing at the time and look towards that as what I will use that day for my planning. If there are large divergents between the models I look at to what the average looks like or consider what the worst case would do to my planning.

Based on your note above it sounds like you are so-so on PW. Is there something else you use and like better?

[Moana Bella]

For Australian coastal, I trust the European model the most, and GFS the least.
I found on the Western Australia coast, they all underestimate the wind by about 10-15 knots. Probably because there is always lots of wind there. But on the Southern and East coast, I have found them to be very good inside of a week.

[mjscottinnc]

For the US east coast including the Bahamas I find GFS to be the closest. But with that said it’s only by the slimmest of margins… 55 to 45 percent. Both have been wildly wrong together and separately. The PW in-house models seem wrong more times then the GFS and European models. I do planning using all of them, pick what looks to be a trend or conscious and go. Once underway, adapt to the actual weather you get.

[markxengineerin]

If I were a better programmer I would
-take a snapshot of the models each day
-keep a 10 day history
-measure the average accuracy of the different models at 1 day, 2 days, 3 days, etc and for different areas. This could be roughly done by using the "current 12 hour" prediction as Truth, but would be even better if there were an easy way to compare to actual measured
-Make an app or website to continuously monitor/share the results

Maybe someone has done it, or someone here could. It would be a fun project and powerful amount of data relatively easy to get.

[SailingHarmonie]

Originally Posted by markxengineerin

If I were a better programmer I would
-take a snapshot of the models each day
-keep a 10 day history
-measure the average accuracy of the different models at 1 day, 2 days, 3 days, etc and for different areas. This could be roughly done by using the "current 12 hour" prediction as Truth, but would be even better if there were an easy way to compare to actual measured
-Make an app or website to continuously monitor/share the results

Maybe someone has done it, or someone here could. It would be a fun project and powerful amount of data relatively easy to get.

If you looked at the actual offerings from predict wind you will find that this is currently available in their Validation tool for wind direction and speed for 1 day to seven day predictions for 1 day to one month time frames... But many here would prefer to talk than actually do data.

[markxengineerin]

It does make sense that they should offer that feature, so, not surprising. Thanks I'll check it out.

[SailingHarmonie]

Originally Posted by GreenWave

Based on your note above it sounds like you are so-so on PW. Is there something else you use and like better?

PredictWind shows the outputs from all the major weather models that are out there and presents the raw outputs from the models. There really are no others. Predict wind is not "accurate" or not, it just reports what the major weather service models are saying. It is exactly the same data that everybody else has.

People who complain about the wind always being stronger than forecast usually just don't understand the presentation of the data. The "wind speed" forecast is a 2 minute average wind speed. So literally HALF THE TIME the wind is blowing harder than that! So, yes, when you are trimming sails you can expect winds stronger than the "forecast" half the time. Even wind gusts are averaged, just over shorter periods, typically 3 seconds. And how many people actually look at the gust forecasts and use that in their evaluation of the conditions?