Why is Wind speed in hurricanes so wrong?



  • I am amazed at the accuracy of Windy hurricane 'forecasts'. OK the max wind speed is off, but you can tell the severity of the storm by its size and color bands. I kept some screen grabs captured last week using the european model and noticed Windy 'forecast' for Irma was spot on (going up west coast of Florida starting Sunday 10 Sept). I now am looking at forecast of Jose for Sept 18 ....wow a monster off the USA east coast and yet another hurricane forming at 20N 40W (while the GFS model does not show this at all). FABULOUS TOOL, CONGRATULATIONS!



  • @Siff The explanation makes perfect sense from a data science perspective. The grid is aggregating data...it is a window function. The simplest example is an average (rectangular window function). Take the average of 10, 10, 20, & 80. The average is 30. Clearly, 80 was included, but the output (30). When the OP says that it "smoothes" away extremal data, they literally mean smooth:
    https://en.wikipedia.org/wiki/Smoothing

    That said, there are better methods that can preserve extremal measurements. These are called "High Resolution Schemes" or "Total Variation Diminishing" methods:
    https://en.wikipedia.org/wiki/High-resolution_scheme
    https://en.wikipedia.org/wiki/Total_variation_denoising

    These let you recover data like this:
    0_1504971007927_Screen Shot 2017-09-09 at 11.28.54 AM.png

    The challenge with using these for weather is scale and computing power.

    Stay safe out there!



  • @Siff The sources that are providing the data sets for the likes of windy.com, has been proven to be selective in what data they distribute. For example the reporting of Earthquakes - Dutchsinse (A YouTuber who operates a channel warning various parts of the world of any imminent earthquake related threats) regularly demonstrates examples of earthquakes being reported on other nations websites, (other meaning non-US) but not by the USGS. This is a regular occurrence. Ergo if the source is unreliable why bother using its data?



  • @Ricky_Lightning See my post, this is not a "data withholding" problem. It's math. There are only so many ways to aggregate a bunch of measurements into one while preserving the character of the data.



  • @meteo-GR what would be the point in comparing the two as you've suggested? The source of the data in both examples, is from the same source.



  • Why are the rain and wind scales not high enough for purposes in hurricanes and unusual weather?



  • @Ottavs Because it is showing averages, not peak measurements.



  • My wind scale only goes up to 60 Kt.



  • @Ottavs Right. It's showing averages. You could have 3 measurements for a city, for example, 50mph, 50mph, and a gust of 150mph. The average is 83mph.



  • Rain scale only goes up to 1.2 in.



  • I think Irma is averaging more than any one component of 60. Sustained winds were reported at 175+. The wind scale offers colors for only up to 60.



  • @Ottavs It's only measuring how much is dropping for that hour, it's not adding up all the rain over time to a single area. 1.2 inches of rain in an hour is a lot.



  • @Ottavs First of all, it's in knots, not mph. Second, sustained wind measurements are much more complicated:
    https://en.wikipedia.org/wiki/Maximum_sustained_wind

    Basically, it's a 1 minute measurement. That's it. Windy is showing you the average wind speed for an hour. They could show you only the max wind speeds everywhere for the hour, but it would likely be very misleading.



  • @Siff Everything you are quoting here comes from research. Now to apply that in mass scale, manage, and sell it cost $$ and I would like ask who do you think is doing that? Who is going to pay for the communications, power supplies, server data gathering, data accuracy, historians, etc... What is out there is what is out there. You are talking about creating and managing a system that reaches the pockets of many numerous political lines and everyone want's to control and pocket $$ for the ability to contribute to the overall success of the best system.



  • @frostymon looking at the wind speed readings at the various sensors. You can see that many of the public sensors reporting valid data up to some time at which either the communications/power/or device has down time. The wind speeds maybe due to the mean of these readings if the data has a good quality else the data is thrown out and the data in time is bad data...not due to the algorithm but the infrastructure.



  • Hola. Para hacer cálculos de viento pueden tomar como referencia el oleaje.
    Tanto el largo como la altura y el desplazamiento, de las mismas.



  • Are Gust measurements smoothed out too or is that real data?



  • @VOLPE-DIEGO interesante



  • Es tan lógico que sea así, como lo es un cálculo de cualquier evento o comunidad. Hay innumerables variantes, dinámicas todas, que sólo permite establecer un mix, un promedio de todas ellas, acotadas también en un período de tiempo. Excelente sitio www.windy.com Lo visto siempre. Gracias.



  • Thank GOD I found this on here. I didn't know the wind speeds were wrong and hubby and I were planning on sticking it out here in our home tomorrow based upon the speeds they were giving.If they are THAT wrong, you should just not have them on here at all.


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