running three find commands in parallel

I am just new to powershell, but have been using dos for years.

I have a .bat file that executes three commands in sequence:

find "aaa" combined0.txt >combined1.txt
find "bbb" combined0.txt >combined2.txt
find "ccc" combined0.txt >combined3.txt

Is there a way in powershell to run these three commands in parallel and only move on to the following command once all three have completed?   If yes, an example would be very much appreciated.

Thanks, Rob