What Weather Models do Phone Apps Use? Why use Programs like Bon Voyage?

So you think everyone started using Windy for the pretty colors, or because we’re dagnabbit millennials who want another excuse to stare at a smartphone?

Can I ask why you pay for Bon Voyage then? The NOAA forecast is available for free. Is it for the cool name?

According to the Windy website:

On Windy we use models GSF with 22km resolution grid, ECMWF with 9km resolution grid and a lot of local models with resolution even 3km.

GSF being the model used by the NWS.

The reason for using Bon Voyage and similar services is analogous to the reason we use GPS maps in the car instead of transferring the position to a paper map. Saves the time and effort of the additional step of constant updates to position.

With the weather the map also changes every 6 hours with each update.

Windy offers multiple models that you can select from, some models being more accurate for certain weather systems and locations than others. This is where the greater accuracy comes in. When they say that on their website they are just referring to the default model displayed.

Bon Voyage and most other modern weather tools offer the same functionality. If you’re only using them to display your position on a weather map you’re not using them correctly.

Context is everything: This thread started because on another thread, posters (not you) were alleging that weather data and weather predicting models from NOAA and NASA were worthless, because of politics and conspiracy theories. I argued this was incorrect.

You narrowly stated that:

I pointed out your statement is factually incorrect, because Windy has on its app NOAA models. Windy would not use them if they thought they were functionally inaccurate.

Perhaps what you meant to say is that totality of users of the Windy app never look at the NOAA models. But that’s just an opinion of yours. My captains look at all the data they can get. They use BVS and they use Windy. They look at this model and that model. I think most mariners would do the same in the volatile GOA and Bering Sea. To prove your point you would have to convince me that mariners do not refer to NOAA models and NASA data. Since I know that to be otherwise, I’m not convinced.

You then make a statement which I completely agree with:

That statement is perfectly reasonable. It is nuanced. It allows for the reality that different nations will focus their weather prediction efforts on their own parts of the world, and on certain regions. But to categorically state that no one uses NOAA models or NASA data is absolutist, and like most absolutist statements outside of physics and mathematics, factually incorrect.

I think you are conflating exclusive use of the NWS website as compared to using Windy, or BVS, and saying no one uses NWS exclusively. I never argued they did. All along I have simply argued this: Mariners rely on NOAA models and NASA data every day, to keep alive. And if you think I’m wrong, consider this: if a NOAA weather model showed your boat in imminent danger from a typhoon, and another model said probably not, would you keep on your present course?

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Windy is BS ,do they launch their own satellites?
When these third party weather prognosticators decide to invest in their own satellites and the means to get them into orbit I will reconsider my opinion of them. I currently consider them scam artists who use the taxpayer funded resources to try and enrich themselves.

I look at the NOAA forecast every update, in fact I just did. Primarily because I’ve seen over reliance on Windy get captains in trouble with sea heights.

You used the NOAA weather forecast as an example. That was a poor example. I provided a very obvious everyday example of why.

To go along with your example, say NOAA is forecasting 60 knots and windy only 45 at a wind direction I can haul with the way my gear is currently set. I will go with the Windy model because it has proven more accurate in the past. If I continually shifted gear to account for severe weather forecasts that didn’t materialize I wouldn’t get much done.

Similarly, if we as a society use our limited resources to combat carbon instead of microplastics we run the risk of shifting our gear for a storm that may not materialize while we end up getting walloped by another.

Are you familiar with programs like Bon Voyage? We used a program from AWT which is now the same company. It’s not just another weather tool it’s a ship routing program.

The key feature is that the ship’s position can be seen in relationship to the various (electronic) weather maps. The ship’s speed of advance is modeled given wind, sea and current and the current position is projected (in 6 hour increments) along the future track.

The last I used it there was no feature that allowed using different models. AWT also send port forecast separately but we also received and used the text weather from the Sat-C and maps from the Fax (later downloaded from the internet).

The routing software is a powerful tool but the text forecast are crucial because of the 6 hour or so delay between when the routers receive the forecasts and when that update arrives on the ship.

Most modern chart plotter software offers the same functionality of routing and at any rate that’s fairly easy to do with Windy. Automated ship routing for weather and it’s accuracy is probably a subject for a different thread. It would be unusual to see a weather program nowadays that didn’t offer at least ECMWF, GFS, NAM and ICON.

You have to put some work in at home going through the archive sites and seeing how each weather system developed vs. the forecast for the time of year, water temps, pressures etc. As with all nautical decisions there is a certain amount of intuition involved and sometimes that is wrong.

If you have a 6 hour delay nowadays something is wrong. I still plot weather systems on occasion to keep in practice but the reality is if something bad enough happens to stop the internet data the fax probably isn’t coming either.

There is delay of several hours, nothing to do with me. Using Alt-F for “BVS” on this document will give a good idea: https://www.ntsb.gov/investigations/AccidentReports/Reports/MAR1701.pdf.

The Windy app could have a lot of value in some situations but ultimately I used the forecasts from the various weather services depending on our location. Can’t do ensemble forecasting / Monte Carlo simulations etc aboard the ship. Also the Windy app doesn’t show the weather fronts.

My formal training in weather routing comes from having taking a class at the union school from the person who wrote this article: Mariner’s Guide to the 500 – Millibar Chart here - :Mariners Weather Log Vol. 52, No. 3, December 2008

I find the article tough sledding but it’s a good reminder of how much skill and knowledge a professional meteorologist brings to the table.

I also took a copy of this book to sea with me: Heavy Weather Avoidance and Route Design: Concepts and Applications of 500 Mb Charts: Chen, Ma-Li, Chesneau, Lee S.: 9780939837786: Amazon.com: Books

Joe is a classmate from Ft. Schuyler ('80), he used his meteorology degree, I didn’t. He now telecommutes fill time from your vicinity (Camden)

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The one that was an instructor was Chesneau. Five day course, very good.

Sienkiewicz does have an impressive resume

. “After graduation I worked for five years as mate and captain on tugboats based out of New York”.


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BVS was at the origin of the ‘El Faro’ disaster.
Not the program itself, it is what it is, but the exclusive use of it, discarding all other info arrived on the bridge, especially the Navtex/Sat-C weather.

The afternoon before the sinking, the crew knew perfectly that they were on a collision course with the hurricane’s center, but BVS did not…

There are no ‘models’ needed to preview the path of a highly volatile hurricane for the next six hours. Today, all real weather data is available in quasi real-time, models could only distort the obvious finding that the hurricane goes South… as did BVS.
AS for the longer term models, only ECMWF had ‘Joaquin’ right over days…

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BVS and other similar programs are very useful for weather routing over a periods out several days for ocean transits and the like.

For shorter time / distance over the next day or two the SAT-C text / wx fax (or via email etc) are most useful.

For the next 24 hr or so the current weathe observations become more important.

All three together for the full picture.

Here’s a screen shot of AWT Savanah to Straits of Gibraltar

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Since you keep referring to it as ‘the Windy app’ and you put ‘phone apps’ in the thread title, you may want to visit the Windy website and spend some time on the Windy community pages if you want to understand the capabilities of the tool for mariners.

There’s certainly enough information to draw your own front lines, although I’m not sure why you would. Using 1930s techniques with modern information availability doesn’t make a lot of sense.

A lot of seafarers look at passage weather:


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Predictwind is another good tool that is often more accurate North of St. Matthew

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For a deep-sea ship that’s like asking why would anyone would call a vessel on VHF Ch-16. Both VHF and Sat-C are part of the required GMDSS equipment on the bridge where there is a licensed operator on watch anytime while underway.

Yes, Windy.com is great tool and I’ve been using it since I learned about it on this site. Nothing wrong with using it but it’s not a substitute for the GMDSS equipment for several reasons.

EDIT: The shipboard GMDSS equipment is just the ship side of the SAFEYNET system.

I’m not sure what you’re referring to. I was referring to drawing front lines, as you said Windy doesn’t display them.