Homepage Query based on User's Category Selection

Hello:

I have a running group that is using my website as a point of reference to find the week’s workouts (there are three runs per week), of whom are on different training “tracks.” Like 10k, 1/2 Marathon, Marathon.

On the homepage, I have created widgets based on a query from Query Wrangler. (Pretty awesome)

There are 3 widgets, one per workout day.

However, I would like to have the user select the “track” (category) they are running from a list (10k, 1/2 marathon), and then the Widget Queries would be UPDATED based on the selection by the user.

The query is set on posts by “track” which are organized as categories.

So is there a way to have a query conditional on an initial selection by a user via a drop-down list available from the homepage?

Thanks!
Catharine