With NOAA's HYSPLIT service, trajectories can be calculated online. You can find instructions on how to do this below:

Click on the pictures to enlarge them.

The following link will take you to the entry form: https://www.ready.noaa.gov/hypub-bin/trajtype.pl

Choose 1 Trajectory Starting Location and NORMAL for the Type of Trajectory.

Here you have to select the weather model and the location where the trajectories start. In the example, we have selected the starting location of the Gordon Bennett Race 2021, Wrocław, Racecourse – Partynice, Poland. (Koordinates: 51.055425 N and 17.000682 E)

Attention: Not all weather models cover the whole world, therefore we choose the GFS model.

Select Meteorological Forecast Circle.

Normally, the last calculation run is suggested, and it is a good idea to select this. If you perform several calculations with different runs, you can see whether the forecast is stable or not.

Model Run Details

1. Trajectory direction: Forward
2. Vertical Motion: Isobaric
3. Start time (UTC): Your choice
4. Your time for this flight altitude
5. Here you can specify how often a new trajectory should be started at intervals. First select 0 so that only one is calculated. Later you can experiment with these options.
6. Coordinates of the starting point.
7. Here you can select up to three heights for which trajectories are calculated.
8. Select Google Earth (kmz)
9. Here you can choose the resolution of the graphics.
10. You can first select the other fields as in the example.

If you click on Request trajectory, you can start the calculation.

Now you have to be patient until the calculation and the creation of the graphics are finished.

Here you can see when the balloon will be where on the trajectory.

Here you can display the trajectory as a gif.

hysplit5step2.pdf

hysplit5step3.kmz

hysplit5step4.txt

This is just one example. Of course, you could experiment with different inputs.

Your comments? Contact Volker Löschhorn.