@ianmcwherter Hello, you can achieve this in two different ways:
When viewing detailed forecast of the location you want, click on the Airgram tab, then you can see graph displaying wind velocity at multiple altitudes and forecast times, all at the same time (good for comparison of forecast times and altitudes, but only for a single location on the map). The following screenshot displays airgram for location 51.451; 1.783 (somewhere in London):
0_1513343421609_airgram11.png
Move the map altitude slider or the map forecast time slider. This updates the whole map and the particles (good for area context of the wind, but only for a specific altitude and specific forecast time). The following screenshot displays wind map + particles at 2017/12/15 13:00 UTC in 800hPa (i.e., 2000m, or 6400ft) altitude
0_1513344319275_airgram22.png