New Windy "sounding" plugin - I suspect wrong speed (units??) in vertical speed profile


  • Meteorologist

    @vicb

    Congrats on getting your sounding profile added to the Windy platform...

    I was looking at your plugin this evening and noticed that the wind speed profile in the SkewT window does not match up with the speed shown in the picker.

    I always select kts when looking at wind speeds. However, it appears that although the kts unit is displayed in the Skewt window, the wind speed values shown in the vertical profile look closer to values associated with km/hr.

    The same goes for both EC and GFS model data.

    Could you check this thanks. Do you need an image showing the discrepancy?

    As an additional comment....did you intend to leave the wind speed scale non-linear in the zoomed option? I see you changed the wind speed profile to linear in the non-zoomed option [thanks for doing that!].


  • Paraglider

    @stitch good catch. The line was still potted with the wrong scale in unzoomed mode. This should be fixed in 0.8.5. (You can specify the version when loading the plugin using the name windy-plugin-soundig@0.8.5 before it becomes the default in a few hours).

    With regards to the scale in zoomed mode:
    The plugin is originally targeted to paraglider pilots.
    That's why I do not display hPa but elevation on the y axis and stop at ~7000m.
    Given that a paraglider fly at ~40km/h we are less interested in speed > 30km/h - we would start flying backward in gusts and also have turbulences.
    That's why having more granularity in the 0-30k range is interesting - we are only remotely interested in >30.
    It does not affect us that much: we wouldn't fly in that zone but knowing the max speed higher still could be interesting.

    That being said I'm open to extending the plugin for more use cases - we started discussing that with @johnckealy.
    What I do not want is to have to configure 20 different options to use the plugin but what I could imagine is to have a handful of different "profiles" (paragliding, meteo, ...) each having a sensible configuration.

    Having a shared google doc could help everybody interested share ideas ? Do you want to start one ?


  • Meteorologist

    Hi @vicb ,

    Your sounding has proven helpful in my aviation forecasting role.
    Could I revisit the parcel trace and propose a modification that may improve this feature (if it can be coded into Windy).

    You stated in another post that you add a sfc temp correction (+3-4degC) to the parcel starting point. Is this because you fly/live in a mountainous area at some elevation that the model incorrectly forecasts in terms of sfc temperature within Windy?

    I have noticed incorrect sfc temp forecast for two of the airports that I forecast for that so happen to be located in mountainous areas. I have applied a rule here where I determine the air temp at a chosen elevation and then apply an adiabatic warming correction to account for the difference in the model surface elevation value and the actual airport location.

    I can demonstrate this using Windy's internal sounding feature. I'll use Queenstown NZ, as this is one of my ports of interest.

    Windy2 ZQN.JPG
    I've selected the location at Queenstown Apt. Down at the bottom of the Sounding window are the reference heights. For the Airport, the EC model height is 2478ft.......whilst the actual height of the airfield is 1171ft.

    That's a difference of 1307ft or ~400m. Taking the dry adiabatic lapse rate at 9.8C/1000m or 3C/1000ft, Queenstown Apt has approx a +4 degC temp correction to the meteogram temp values displayed by Windy.

    My question/request.....Would this approach work for your Sounding Plugin????

    If you can determine/calculate the height difference between the model surface height and the actual surface and apply this temp correction value to the parcel surface starting temp, I think you might have a more accurate parcel trace add on that could be applied to anywhere around the globe.

    My next request......if this could be achieved (and shows promising results), could you apply the modified parcel trace for all forecast hours?

    Happy to discuss (all of the above) :)


  • Paraglider

    That's probably something we can try.

    The thing is that different model report different things.
    I think that EC has all of model elevation, actual elevation and sfc temp while GFS only has actual? elevation.

    I have chosen to use the model elevation when available because what's below probably do not make a lot of sense ?


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