  Speed ensemble of bistable (combustion) fronts in mean zero stationary
Gaussian shear flows inside two and three dimensional channels is studied with
a min-max variational principle. In the small root mean square regime of shear
flows, a new class of multi-scale test functions are found to yield speed
asymptotics. The quadratic speed enhancement law holds with probability
arbitrarily close to one under the almost sure continuity (dimension two) and
mean square H\"older regularity (dimension three) of the shear flows. Remarks
are made on the conditions for the linear growth of front speed expectation in
the large root mean square regime.
