  We extend the idea of interval pattern avoidance defined by Yong and the
author for $S_n$ to arbitrary Weyl groups using the definition of pattern
avoidance due to Billey and Braden, and Billey and Postnikov. We show that, as
previously shown by Yong and the author for $GL_n$, interval pattern avoidance
is a universal tool for characterizing which Schubert varieties have certain
local properties, and where these local properties hold.
