Maybe they should say Peak wind velocity for that period?
That's how most seem to interpret it.
There are also two other gust parameters listed, but I don't know if they actually work. (Not everything in their protocol spec works as listed)
Quote
windgustmph_10m - [mph past 10 minutes wind gust mph ]
windgustdir_10m - [0-360 past 10 minutes wind gust direction]
I'm not sure how they would plot windgustdir on their current graphs.